Title of Invention	AROMATIC BISETHER DIAMINES HAVING PENDANT DIPHENYL PHOSPHINE OXIDE AND A PROCESS FOR PREPARING THE SAME
Abstract	The present invention relates to Aromatic bisether diamines having pendant diphenyl phosphine oxide and a process for preparing the same. More specifically, the present invention relates to a variety of new phosphorus containing aromatic diamines prepared from cashew nut shell liquid (CNSL), which is a renewable resource material. The present invention particularly relates to novel [2, 4-bis-(4"-amino-3"-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide, [2, 4-bis-(4"-amino-3"-alkylphenoxy) phenyl]-diphenyl phosphine oxide,[2, 4-bis-(6"-amino-3"-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide, [2, 4-bis-(6"-amino-3"-alkylphenoxy) phenyl]-diphenyl phosphine oxide; [2, 5-bis-(4-amino-3"-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide, [2, 5-bis-(4"-amino-3"-alkylphenoxy) phenyl]-diphenyl phosphine oxide, [2, 5-bis-(6"-amino-3"-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide, [2, 5-bis-(6"-amino-3"-alkylphenoxy) phenyl]-diphenyl phosphine oxide and further provides a method for their preparation.

Title of Invention

AROMATIC BISETHER DIAMINES HAVING PENDANT DIPHENYL PHOSPHINE OXIDE AND A PROCESS FOR PREPARING THE SAME

Abstract

The present invention relates to Aromatic bisether diamines having pendant diphenyl phosphine oxide and a process for preparing the same. More specifically, the present invention relates to a variety of new phosphorus containing aromatic diamines prepared from cashew nut shell liquid (CNSL), which is a renewable resource material. The present invention particularly relates to novel [2, 4-bis-(4"-amino-3"-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide, [2, 4-bis-(4"-amino-3"-alkylphenoxy) phenyl]-diphenyl phosphine oxide,[2, 4-bis-(6"-amino-3"-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide, [2, 4-bis-(6"-amino-3"-alkylphenoxy) phenyl]-diphenyl phosphine oxide; [2, 5-bis-(4-amino-3"-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide, [2, 5-bis-(4"-amino-3"-alkylphenoxy) phenyl]-diphenyl phosphine oxide, [2, 5-bis-(6"-amino-3"-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide, [2, 5-bis-(6"-amino-3"-alkylphenoxy) phenyl]-diphenyl phosphine oxide and further provides a method for their preparation.

Full Text	Technical Field: The present invention relates to Aromatic bisether diamines having pendant diphenyl phosphine oxide and a process for preparing the same. The present invention also relates to phosphorus containing aromatic diamines from cashew nut shell liquid (CNSL), which is a renewable resource material. The invention is in the field of Organic Chemistry and relates more particularly to the preparation of novel substituted diphenyl phosphine oxides such as 1. [2, 4-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide. 2. [2, 4-bis-(4'amino-3'-alkylphenoxy) phenyl]-diphenyl phosphine oxide. 3. [2,4-bis-(6-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide. 4. [2, 4-bis-(6'-amino-3'-alkylphenoxy) phenyl]-diphenyl phosphine oxide. 5. [2, 5-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide. 6. [2, 5-bis-(4'-amino-3'-alkylphenoxy) phenyl]-diphenyl phosphine oxide. 7. [2, 5-bis-(6'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide. 8. [2, 5-bis-(6'-amino-3'-alkylphenoxy) phenyl]-diphenyl phosphine oxide. These compounds find end-use as monomers for the synthesis of polyamides, polyamide-imides and polyimides and as curing agents for epoxy resins for achieving atomic oxygen resistance to protect structures in Space environment. Background and prior art: It is well known in the prior art that incorporation of a long alkyl chain in polymer backbone imparts processability to the polymer. The improved properties due to such incorporation of a long alkyl chain benefit a wide range of applications, which seek better performance with improved processability. It is therefore of great interest and importance to synthesize new phosphine-oxide containing diamines with alkyl group in their structure, more particularly from Cashew nut shell liquid (CNSL) which is readily available commercially and is a renewable resource material. In the prior art diamines are known to be useful chemicals. They have been used as bifunctional monomers in preparation of various polymers, such as polyamides, polyiraides, polyazomethines, polyamide-imides etc. The development of new aromatic diamines; which are capable of providing polymers with high processability and are also useful in applications such as interlayer dielectrics, alignment liquid crystal films and light wave guide materials; is an area of importance. Monomer diamine containing long alkyl chain is expected to produce polymers having increased segmental mobility, solubility and hence improved processability of the material; thereby providing materials with application in alignment liquid crystal films. It is therefore of great interest to synthesize new diamines with alkyl group in their structure. It is also of importance and interest to develop aromatic diamines, which are easily and economically obtained from CNSL, since CNSL is readily available commercially and is also a renewable resource. [Indian Patent No. 178216 Madhusudan et al., Ind. J. Tech., 347 (1973); Jadhav, A. S.; Maldar, N. N.; Shinde, B. M.; Vernekar, S. P.; J. Polym. Sci. Polym. Chem. Ed. 29, 147 (1991)]. One of the useful approaches to improve the processability without extreme loss of their thermal stability is the introduction of flexible groups such as • aryl ether, aryl sulfide, isopropyl group [Hsiao, S. H. et al, Macromol. Chem. Phys.; 197, 1255-1272 (1996)]. Further these new aromatic diamines are tailored to include the diphenyl phosphine oxide as pendant groups, which can impart special properties. When these diamines, are potentially used to synthesize high performance polymers; resulting polymers are expected to have special properties and applications. In this approach, the diphenyl phosphine oxide group would be forced to protrude out of the surface (in micro / nano scale) when films are cast from the potential high performance polymers which are synthesized from these diamine monomers. These diphenyl phosphine oxide groups in the prepared polymers are expected to effectively interact with atomic oxygen forming protective phosphate layer. Thus, minimum amount of diphenyl phosphine oxide group would be required to achieve atomic oxygen resistance property for the proposed high performance polymers. Few researchers have concentrated their efforts on aromatic bifunctional monomers, diamines or bisphenols or dihalo compounds from CNSL [Ghatge, N. D.; Maldar, N. N.; Polymer; 25,1353 (1984); More, A. S.; Wadgaonkar, P. P.; Gnanou, Y.; /. Amer.Chem. Soc; 128 (5), 8158 (2006); Selvakannan, P. R.; Kumar, P. S.; More, A. S.; Shingte, R. D.; Wadgaonkar, P. P.; Sastry, M.; Langmuir, 20, 295 (2004). Selvakannan, P.R.; Kumar, P.S.; More, A. S.; Shingte, R. D.; Wadgaonkar, P. P.; Sastry, M.; Advanced Materials 16, 966 (2004); Sadavarte, N. V.; Halhalli, M. R.; Avadhani, C. V.; Wadgaonkar, P. P.; Eur. Polym. J.; 45 582 (2009)], which were utilized to prepare a wide number of organic polymers. However in all above bifunctional monomers only long pentadecyl alkyl group' derived from CNSL was incorporated so that the processability of resulting polymers was improved. However, they have one major difficulty of low resistance to Atomic Oxygen; which is required for better application and uses. Some reports appeared on high performance polymers from phenyl phosphine oxide, bulky phosphorus groups, phosphinic acid, perflurocyclobutyl with phenylphosphine oxide and diphenyl phosphine oxide moiety containing monomers; but these did not contain flexible long pentadecyl alkyl unit derived from CNSL. [Connell, J. W., et al.; Polymer; 36, 5 (1995); Liu, Y. L., et al.; J. Appl. Polym. Sci; 89, 791 (2003); Miyatake, K., et al.; J. Polym. Sci Polym. Chem. Ed.; 39, 1854 (2001); Jin, J., et al.; Macromolecules; 36, 9000 (2003); Smith, C. D., et al.; High Perform. Polym.; 3, 211 (1991); Smith, J. G., et al.; Polymer; 35, 2834 (1994)]. Thus, until now, there are no reports on bifunctional aromatic amines wherein long pentadecyl alkyl group' derived from CNSL and "pendant diphenyl phosphine oxide" group are simultaneously incorporated. Therefore it is of interest and importance to synthesize new bifunctional phosphorus containing aromatic diamines which may lead to special property like 'Atomic Oxygen resistance' and space-durable materials of the polymers made from these diamine monomers. Objectives: The primary object of the invention is to provide Aromatic bisether diamines having pendant diphenyi phosphine oxide. Another object of the invention is to synthesize monomers containing aromatic diamines with pendant diphenyi phosphine oxide group from aromatic diamines prepared from Cashew nut shell liquid (CNSL) to achieve atomic oxygen resistance and space durability for structures made using such monomer as precursor. Yet another object of the invention is to synthesize new monomers that would find end use in the synthesis of polyamides, polyamide-imides and polyimides and as curing agents for epoxy resins. Still another object of the invention is to synthesize new monomers from cheap and commercially available renewable resource material like Cashew nut shell liquid. Summary of the Invention: The present invention relates to Aromatic bisether diamines having pendant diphenyl-phosphine oxide group of formula (I). wherein, Ph represent phenyl group; X\| and X2 are independently selected from a group of wherein, R is an alkyl group with at least 8 carbon atoms; and R is either ortho or para to the amine functional group and the two ether linkages on benzene ring are in 1,4 (para to each-other) or 1,3 (meta to each-other) position represented by formula la and la' respectively and the pendant diphenyl phosphine oxide group is ortho to one of the ether linkages. Novel compounds falling within the general formula are exemplified hereinafter 1. [2, 4-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide. 2. [2, 4-bis-(4'-amino-3'-alkylphenoxy) phenylj-diphenyl phosphine oxide. 3. [2, 4-bis-(6'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide. 4. [2, 4-bis-(6'-amino-3'-alkylphenoxy) phenylj-diphenyl phosphine oxide. 5. [2, 5-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide. 6. [2, 5-bis-(4'-amino-3'-alkylphenoxy) phenylj-diphenyl phosphine oxide. 7. [2, 5-bis-(6'-ammo-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide. 8. [2, 5-bis-(6'-amino-3'-aIkylphenoxy) phenylj-diphenyl phosphine oxide. This invention also relates to a process for preparing bisether diamines of formula (I). In a particular embodiment, the inventors have prepared [2, 4-bis-(4'-amino-3'-pentadecyl phenoxy)phenyl-diphenyl phosphine oxide] (ATHDPPO), containing ether linkage, flexible long pendant alkyl group (C15H3]) and phenyl phosphine oxide, for higher flexibility and comparatively lower Tg without sacrificing excellent mechanical and thermal properties of the conventional polyimides. Therefore, the present invention provides arylphosphine oxide derivatives having ether linkage(s), long alkyl groups and phosphine oxide(s) in order to show superior space environment resistant and low dielectric constant without sacrificing excellent properties of polyimides / polyamides. Detailed Description of invention: wherein Xi, X2 and Ph are as defined above which have potential application in manufacture of processable polymers required in for example, alignment liquid crystal films. In the compound of formula (I), R is an alkyl group with 8 to 18 carbon atoms; which is primary, secondary or tertiary alkyl, n-pentadecyl; C15 mono-olefinic group, Cis di-olefinic group, C15 tri-olefinic group and any mixture thereof; For example, the most preferred due to its availability in CNSL is the n-pentadecyl (C15H31) group. The process for preparing bisether diamines of formula (I) comprises the following steps: 1) Subjecting substituted / unsubstituted diphenylphosphinic halide of formula A with 2,4-difluoro bromo-benzene of formula B or 2,5-difluoro bromo-benzene of formula B' under Grignard reaction conditions to obtain (2,4-diflurophenyl) diphenyl phosphine oxide of formula 2(a) or (2,5-diflurophenyl) diphenyl phosphine oxide of formula 2(a') 2) Distilling and hydrogenating commercial cardanol (CNSL) to obtain 3-pentadecyl phenol; diazotizing or nitrating and reducing the same to 4- or 6-amino-3- pentadecylphenol of formula 2(b) 3) reacting the compound of formula 2(a) or formula (2a') obtained in Step (1) with 4- or 6-amino-3-pentadecyl phenol of formula 2(b) obtained in Step (2) under reflux, the presence of a base and separating the reaction product and isolating the compound of formula (la) or (la') Therefore, other compounds of interest may be prepared in the same manner by carrying out the steps with compounds having the desired substituents. In a particular embodiment of step (1) of the above mentioned process, formula (2a) or formula (2a') is prepared by reacting 2,4-difluoro bromo-benzene of formula (B) or 2,5-difluoro bromo-benzene of formula (2b') with magnesium in tetrahydrofuran or diethyl ether in diphenylphosphinic chloride of formula (A), to obtain the compound (2a) or compound (2a'). A molar ratio of reactants is 1:1 to 1.2:1 (Grignard reagent: diphenylphosphinic chloride) and the reaction is performed at 0-5 °C for 3h and then at room temperature for 24 h. The above reaction mixture is poured in cooled aq. 5% H2SO4. In particular, diamine monomer of formula la or la' is prepared from nucleophilic substitution reaction of compound (2a) or compound (2a') and compound (2b) in presence of potassium carbonate and a polar aprotic solvent dimethylacetamide (DMAc) by azeotropic distillation with toluene for 6 h at 135'C and finally heated after removal of toluene at 165'C for 16 h. The isolation of the product is done in 5 % acetic acid solution to yield the corresponding compound of formula la or la'. The synthesis of the diamine is a key feature of this invention. This is prepared from commercially available starting materials in two or more steps with relatively good yield and purity. The intermediates and products formed in each step (l)-(2)-(3) can be isolated by conventional means. These include solvent removal, washing, drying and recrystallization. This invention further includes a process for preparing a polyimide which comprises reacting 3,3',4,4' benzophenone tetracarboxylic dianhydride with [2,4-bis-(4'-amino-3'-pentadecylphenoxy) phenylj-diphenyl phosphine oxide] in 1:1 stoichiometric ratio and subsequently chemically imidizing the resulting polymer with pyridine in the presence of acetic anhydride and then completing the imidization step by heating the reaction mixture. This invention further includes polyimides obtained by the above process. Having generally described the invention, a more complete understanding thereof can be obtained by reference to the following examples that are provided for purposes of illustration only and do not limit the invention in any manner whatsoever to these examples. Examples The invented method is described in detail for a particular embodiment of new monomers viz. Diphenyl phosphine oxide containing aromatic diamines represented by Formula (la) and Formula (la'). Example 1 Preparation of [2, 4- bis-(4'-ammo-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide] (ATHDPPO) (la) Step 1: Preparation of 2,4-difluoroplienyldiplienylphosphine oxide (2a): Into a 250 mL three necked round bottom flask equipped with a magnetic stirrer, a thermometer, a nitrogen gas inlet, a pressure equalizing addition funnel and a reflux condenser with drying tube were placed predried magnesium turnings (0.1 mol, 2.43 g) and dry and freshly distilled tetrahydrofuran (THF, 20 mL). The mixture was cooled to -S'C using an ice/water bath. A solution of 2,4-difluoro bromo-benzene (0.1 mol, 19.4 g, 11.36 mL) (B) in THF (40 mL) was placed in the pressure equalizing addition funnel and added drop wise over a period of 1 h. The reaction is initiated with some Iodine crystals, effervescence began as reaction continues. The mixture was allowed to warm to room temperature. The mixture was stirred at room temperature for 3 h and the flask was subsequently placed in the ice/water bath to cool the solution to "S'C. 20% molar excess of above Grignard reactant was taken for the reaction. A solution of diphenylphosphinic chloride (0.083 mol, 19.588 g) (A) in THF (25 mL) was added drop wise over a period of 1 h. The reaction mixture was allowed to warm to room temperature and was stirred under nitrogen for 24 h. The resultant brown solution was poured into 5% H2SO4 solution (250 mL) and the THF layer washed with saturated solution of NaHCOj and the solvent removed after drying over anhydrous sodium sulphate. Finally the residue was distilled under reduced pressure (175'C / 10 mm) to yield the product; which was washed with hexane to remove oily part. Yield (2a) is 16 g (61.39 %). m.p. 89-90'C.; crystallization from mixture of toluene and hexane (1:1) gave white solid 15.6 g (60 % yield) having m.p. IITC. (Lit. m. p. 111.2-111.3 "C). Step 2: Syntliesis of 4-aniino-3-pentadecylplienol (2b) a) Commercial cardanol; obtained from CNSL; was distilled under vacuum at 190-220'C / 5 mm of Hg, to give pale-yellow cardanol. Redistilled cardanol was hydrogenated at 70'C in the pressure autoclave (600 psi pressure / VO'C) using Rainy-Ni catalyst to give 3-pentadecylphenol. (Also known as Tetrahydroanacardol-THA) b) 4-Amino-3-pentadecylphenol was synthesized from diazonium salt of sulphanUic acid and 3-pentadecylphenol by forming diazonium salt in basic conditions at low temperature; which was reduced with sodium dithionite at about 75 "C to yield the desired araino-phenol, (4-amino-3-pentadecylphenol, also known as 4-amino-tetrahydroanacardol- ATHA); derived from renewable raw material. 3-pentadecyl phenol (0.025 mol, 7.5 g), dissolved in KOH (0.0687 mol, 3.9 g) and 50 mL 95% ethyl alcohol were placed in one liter three necked round bottom flask fitted with a stirrer, a thermometer and a reflux condenser and cooled to -SC. To this diazonium salt, prepared as below, was added. (A) In 250 mL beaker sulphanilic acid (0.03 mol, 5.25 g), 50 mL water were placed and to this anhyd. NaaCOa (0.0125 mol, 1.325 g), was added with stirring till effervescence disappear. The mixture was warmed to get clear solution and it was then cooled to 0'C. (B) In another beaker sodium nitrite (NaN02) (0.027 mol, 1.85 g) was dissolved in 10 mL water and cooled to 0°C. Then cooled sodium nitrite solution was added to cooled solution (A) and this mixed solution was immediately added to beaker containing 5.1 mL cone. HCl and 15 g ice. Light pink solid precipitated out. It was allowed to settle (liquid was drained out slowly leaving solid; diazonium salt of sulphanilic acid; behind). To this solid 25 mL cold ethanol was added and the suspension was added to alkaline solution of 3-pentadecyl phenol. The resulting red-dye solution was stirred for 2 h in ice bath and then stirred at room temperature for 1 h. The red solution was heated with stirring to 60-65'C and a solution of sodium dithionite (11.25 g in 25 mL water) was added. Colour of reaction mixture slowly changed from dark red to pale tan, indicating completion of reduction. A solution of 4 mL glacial acetic acid in 30 mL water was added and reaction mixture was refluxed for 1 h. The contents of the flask were cooled, when crude 4-amino 3-pentadecyl phenol (2b) separated. The product was filtered off and washed with plenty of water (till filtrate became colourless) and the product was recrystallized from ethanol. Yield 5 g (63 %) ra.p. lOS-lOe'C (Lit m.p. 105°C). Step 3: Preparation of [2,4-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide (ATHDPPO) (la): Into a 100 mL three necked round bottom flask equipped with a magnetic stirrer, a thermometer and a Dean-Stark trap equipped with a drying tube were placed 2, 4-difluorophenyldiphenylphosphine oxide (2a) (0.006 mol, 1.88 g), 4-amino-3-pentadecylphenol (2b) (0.012 mol, 3.83g), potassium carbonate (0.0144 mol, 1.98 g, 20% molar excess), N, N dimethyl acetamide (DMAc) (15 mL) and toluene (35 mL). The mixture was heated to reflux, while removing water via azeotropic distillation. After 6 h, the toluene was removed from the reaction and the residual solution was heated at 165'C, for 16 h. The reaction mixture was cooled to room temperature and the solution was poured into 300 mL of cold water containing 5 % acetic acid with vigorous stirring. A tan solid, obtained after stirring for 45 minutes; was filtered, washed with plenty of water, dried under vacuum at TO'C to afford (la); 4.6 g (84% yield). The solid was recrystallized twice from methanol with charcoal treatment to yield 3.8 g (70% yield) of a light cream solid; m.p. 62-64°C. The FT-IR spectrum (in CHCI3), of Diamine (la) exhibited characteristic absorptions at 3355 (as characteristic doublet above 3300 cm', -NH2 group), at 1167 (P=0) and at 1240 cm' [ether (Ar-O-Ar)]. The 'H and 'C NMR spectra supported the assigned structure of the compound (la). The 'H NMR (in CDCI3), showed the aromatic protons of the aromatic ring (with amine and aliphatic chain) at 6.25 to 6.72 5 whereas peaks at 7.34 to 7.86 6 are due to the aromatic protons of ring with the P=0 group. The peak at 0.86 (triplet) [the terminal methyl of the aliphatic chain (C15H31)] and peaks at 1.24, 1.51 and 2.16 are assigned to (CH2)i4 aliphatic protons in the C15H31 group. Peak at 3.5 5 is of amino - protons. The C NMR (CDCI3) spectrum of (la); showed eighteen peaks corresponding to different eighteen aromatic carbons and peaks below 70 ppm were of different aliphatic carbons. DEPT spectrum showed disappearance of aromatic tertiary carbons and CH2 carbons (of the aliphatic chain) were seen as downside of the spectrum (negative side) at 36.65 and 24.71 5. Similarly preparation of [2,5-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide (la') was performed from (2a'); obtained from 2,5 difluoro bromo-benzene; and (2b). Example 2 Preparation of Polyimide from 3, 3', 4, 4' benzophenone tetracarboxylic dianhydride (BTDA) and [2, 4'bi$-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide] (ATHDPPO) using 1:1 stoichiometry Into a 100 mL three-necked round-bottom flask equipped with a magnetic needle, nitrogen gas inlet, and calcium chloride guard tube were placed ATHDPPO (la) (1.0 mmol, 0.912 g) and N-methylpyrrolidone (NMP) (6.2 mL) and the solution was cooled to 0'C in ice bath. To this cold solution, solid 3, 3', 4, 4' benzophenone tetracarboxylic dianhydride (BTDA) (1.0 mmol, 0.322 g) was added in small quantity lots over 1 h and solution was stirred for 3 h at 0°C and for 24 h at room temperature under a nitrogen atmosphere. The viscosity of the reaction mixture increased. Some part of polymerization solution, (poly amic acid), was added into methanol to precipitate poly(amic acid). The remaining polymer solution was chemically imidized by 4 mL of acetic anhydride and 0.5 g of pyridine in 4 mL dry benzene, at room temperature for 24 h. The polyimide solution was poured into methanol, to precipitate polymer, which was filtered, washed with hot water, methanol and then dried under vacuum at 70C for 6 h to afford a white, powder material. In order to ensure complete imidization, chemical imidization was supplemented by thermal imidization; where in chemical imidized polymer was taken in RB flask and heated step wise for 1 h at 100°C, 1 h at 150'C, 1 h at 200'C and finally at 230°C for 20 min. This process ensured the complete imidization. The overall yield of polyimide (ATHPI-1) was 98%. The inherent viscosity (rii„h) of poly (amic acid) was measured at 0.5% polymer concentration in DMAc at 30 ± 0.1°C by Ubbelohde viscometer. Polymer had inherent viscosity (riinh) 0.3 dlVg. The polyimides synthesized from the diamine monomer are expected to show better atomic oxygen resistance properties. While the invention has been illustrated and described in typical embodiments, it is not intended to be limited to the details shown, since various modifications and substitutions can be made without departing in any way from the spirit of the present invention. As such, further modifications and equivalents of the invention herein disclosed may occur to persons skilled in the art using no more than routine experimentation, and all such modifications and equivalents are believed to be within the spirit and scope of the invention as defined by the following claims. Advantages: The diamines disclosed here can be used in making classes of high performance polymers; they can be used as coupling agents, cross linking agents, plasticizers etc. And further, such prepared materials are suitable for semiconductor package materials, intermediates for optical fibers, optical materials and adhesives for metals etc. These materials or their derivatives can also be used in surface coatings, paints, lacquers, varnishes; in foundry industry, brake-liners, and as specialty hydrophobic, flexible, water resistant resins / polymers. WE CLAIM: 1. Aromatic bisether diamines having pendant diphenyl phosphine oxide group of formula (I). wherein, Ph represent Phenyl group; X1 and X2 are independently selected from a group of wherein, R is an alkyl group with at least 8 carbon atoms; and R is either ortho or para to the amine functional group and the two ether linkages on benzene ring are in 1,4 (para to each-other) or 1,3 (meta to each-other) position represented by formula la and la' respectively and the pendant diphenyl phosphine oxide group is ortho to one of the ether linkages. 2. The aromatic bisether diamines as claimed in claim 1, wherein the compound is either [2, 4-bis-(4'-amino-3'- alkylphenoxy) phenyl]-diphenyl phosphine oxide or [2, 5-bis-(4'-amino-3'- alkylphenoxy) phenylj-diphenyl phosphine oxide. 3. The aromatic bisether diamines as claimed in claim 1, wherein the compound is either [2, 4-bis-(4'-amino-3'-pentadecylphenoxy) phenylj-diphenyl phosphine oxide or [2, 5-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide. 4. The aromatic bisether diamines as claimed in claim 1, wherein the compound is either [2, 4-bis-(6'-amino-3'-alkylphenoxy) phenylj-diphenyl phosphine oxide or [2, 5-bis-(6'-amino-3-alkylphenoxy) phenylj-diphenyl phosphine oxide. 5. The aromatic bisether diamines as claimed in claim 1, wherein the compound is either [2, 4-bis-(6'-amino-3'-pentadecylphenoxy) phenylj-diphenyl phosphine oxide or [2, 5-bis-(6'-amino-3'-pentadecylphenoxy) phenylj-diphenyl phosphine oxide. 6. A process for preparing aromatic bisether diamines of formula (I) wherein, Ph represent Phenyl group; X\| and X2 are independently selected from a group of wherein, R is an alkyl group with at least 8 carbon atoms; and R is either ortho or para to the amine functional group and the two ether linkages on benzene ring are in 1,4 (para to each-other) or 1,3 (meta to each-other) position represented by formula la and la' respectively and the pendant diphenyl phosphine oxide group is ortho to one of the ether linkages. 1) subjecting substituted / unsubstituted diphenylphosphinic halide of formula A with 2,4-difluoro bromo-benzene of formula B or 2,5-difluoro bromo-benzene of formula B' under Grignard reaction conditions to obtain (2, 4-diflurophenyl) diphenyl phosphine oxide of formula 2(a) or (2, 5-diflurophenyl) diphenyl phosphine oxide of formula 2(a') : 2) Distilling and hydrogenating commercial cardanol (CNSL) to obtain 3- pentadecyl phenol, diazotizing / nitrating and reducing the same to 4- or 6-amino-3- pentadecylphenol of formula 2(b): 3) reacting the compound of formula 2(a) or formula 2(a') obtained in Step (1) with 4- or 6-amino-3-pentadecyl phenol of formula 2(b) obtained in Step (2) under reflux in the presence of a base and separating the reaction product and isolating the compound of formula (la) or (la'). 7. The process as claimed in claim 6, wherein the compound of formula (2b) is 4-amin( 3-pentadecyl phenol and the compound of formula (la) or (la') is 8. The process as claimed in claim 6, wherein the compound of formula (2a) or formula (2a') is isolated by washing with aqueous acid particularly with aqueous sulfuric acid in a concentration of 1% to 20%. 9. The process as claimed in claim 6, wherein the reaction under step 3 is carried out at 120"C to 170°C in the presence of an aprotic solvent selected from polar aprotic solvent like N-methylpyrrolidinone, N, N-dimethylacetaraide, dimethyl sulphoxide, hexamethyl phosphoramide, N, N-dimethyl formamide or mixtures thereof. 10. The process as claimed in claim 6, wherein the reaction under step 3 is carried out in the presence of an alkali selected from Na2C03, K2CO3, NaOH, KOH or a mixture thereof. 11. A process for preparing a polyimide comprising the step of reacting 3, 3', 4, 4' benzophenone tetracarboxylic dianhydride with [2,4-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide of formula (la) or [2,5-bis-(4'-amino-3'-pentadecylphenoxy) phenylj-diphenyl phosphine oxide of formula (la') in 1:1 stoichiometric ratio and subsequently chemically imidizing the resulting polymer with pyridine in the presence of acetic anhydride and then completing the imidization step by heating the precipitated polymer. 12. A polyimide obtained by a process as claimed in claim 11.

Full Text

Technical Field:
The present invention relates to Aromatic bisether diamines having pendant diphenyl phosphine oxide and a process for preparing the same.
The present invention also relates to phosphorus containing aromatic diamines from cashew nut shell liquid (CNSL), which is a renewable resource material.
The invention is in the field of Organic Chemistry and relates more particularly to the preparation of novel substituted diphenyl phosphine oxides such as
1. [2, 4-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide.
2. [2, 4-bis-(4'amino-3'-alkylphenoxy) phenyl]-diphenyl phosphine oxide.
3. [2,4-bis-(6-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide.
4. [2, 4-bis-(6'-amino-3'-alkylphenoxy) phenyl]-diphenyl phosphine oxide.
5. [2, 5-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide.
6. [2, 5-bis-(4'-amino-3'-alkylphenoxy) phenyl]-diphenyl phosphine oxide.
7. [2, 5-bis-(6'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide.
8. [2, 5-bis-(6'-amino-3'-alkylphenoxy) phenyl]-diphenyl phosphine oxide.
These compounds find end-use as monomers for the synthesis of polyamides, polyamide-imides and polyimides and as curing agents for epoxy resins for achieving atomic oxygen resistance to protect structures in Space environment.
Background and prior art:
It is well known in the prior art that incorporation of a long alkyl chain in polymer backbone imparts processability to the polymer. The improved properties due to such incorporation of a long alkyl chain benefit a wide range of applications, which seek better performance with improved processability. It is therefore of great interest and importance to synthesize new phosphine-oxide containing diamines with alkyl group in their structure, more particularly from Cashew nut shell liquid (CNSL) which is readily available commercially and is a renewable resource material.
In the prior art diamines are known to be useful chemicals. They have been used as bifunctional monomers in preparation of various polymers, such as polyamides, polyiraides, polyazomethines, polyamide-imides etc. The development of new aromatic diamines; which are capable of providing polymers with high processability and are also useful in applications such as interlayer dielectrics, alignment liquid crystal films and light wave guide materials; is an area of importance. Monomer diamine containing long alkyl chain is expected to produce polymers having increased segmental mobility, solubility and hence improved processability of the material; thereby providing materials with application in alignment liquid crystal films. It is therefore of great interest to synthesize new diamines with alkyl group in their structure. It is also of importance and interest to develop aromatic diamines, which are easily and economically obtained from CNSL, since CNSL is readily available commercially and is also a renewable resource. [Indian Patent No. 178216 Madhusudan et al., Ind. J. Tech., 347 (1973); Jadhav, A. S.; Maldar, N. N.; Shinde, B. M.; Vernekar, S. P.; J. Polym. Sci. Polym. Chem. Ed. 29, 147 (1991)]. One of the useful approaches to improve the processability without extreme loss of their thermal stability is the introduction of flexible groups such as • aryl ether, aryl sulfide, isopropyl group [Hsiao, S. H. et al, Macromol. Chem. Phys.; 197, 1255-1272 (1996)].
Further these new aromatic diamines are tailored to include the diphenyl phosphine oxide as pendant groups, which can impart special properties. When these diamines, are potentially used to synthesize high performance polymers; resulting polymers are expected to have special properties and applications. In this approach, the diphenyl phosphine oxide group would be forced to protrude out of the surface (in micro / nano scale) when films are cast from the potential high performance polymers which are synthesized from these diamine monomers.

These diphenyl phosphine oxide groups in the prepared polymers are expected to effectively interact with atomic oxygen forming protective phosphate layer. Thus, minimum amount of diphenyl phosphine oxide group would be required to achieve atomic oxygen resistance property for the proposed high performance polymers.
Few researchers have concentrated their efforts on aromatic bifunctional monomers, diamines or bisphenols or dihalo compounds from CNSL [Ghatge, N. D.; Maldar, N. N.; Polymer; 25,1353 (1984); More, A. S.; Wadgaonkar, P. P.; Gnanou, Y.; /. Amer.Chem. Soc; 128 (5), 8158 (2006); Selvakannan, P. R.; Kumar, P. S.; More, A. S.; Shingte, R. D.; Wadgaonkar, P. P.; Sastry, M.; Langmuir, 20, 295 (2004). Selvakannan, P.R.; Kumar, P.S.; More, A. S.; Shingte, R. D.; Wadgaonkar, P. P.; Sastry, M.; Advanced Materials 16, 966 (2004); Sadavarte, N. V.; Halhalli, M. R.; Avadhani, C. V.; Wadgaonkar, P. P.; Eur. Polym. J.; 45 582 (2009)], which were utilized to prepare a wide number of organic polymers. However in all above bifunctional monomers only long pentadecyl alkyl group' derived from CNSL was incorporated so that the processability of resulting polymers was improved. However, they have one major difficulty of low resistance to Atomic Oxygen; which is required for better application and uses. Some reports appeared on high performance polymers from phenyl phosphine oxide, bulky phosphorus groups, phosphinic acid, perflurocyclobutyl with phenylphosphine oxide and diphenyl phosphine oxide moiety containing monomers; but these did not contain flexible long pentadecyl alkyl unit derived from CNSL. [Connell, J. W., et al.; Polymer; 36, 5 (1995); Liu, Y. L., et al.; J. Appl. Polym. Sci; 89, 791 (2003); Miyatake, K., et al.; J. Polym. Sci Polym. Chem. Ed.; 39, 1854 (2001); Jin, J., et al.; Macromolecules; 36, 9000 (2003); Smith, C. D., et al.; High Perform. Polym.; 3, 211 (1991); Smith, J. G., et al.; Polymer; 35, 2834 (1994)]. Thus, until now, there are no reports on bifunctional aromatic amines wherein long pentadecyl alkyl group' derived from CNSL and "pendant diphenyl phosphine oxide" group are simultaneously incorporated. Therefore it is of interest and importance to synthesize new bifunctional phosphorus containing aromatic diamines which may lead to special property like 'Atomic Oxygen resistance' and space-durable materials of the polymers made from these diamine monomers.

Objectives:
The primary object of the invention is to provide Aromatic bisether diamines having pendant diphenyi phosphine oxide.
Another object of the invention is to synthesize monomers containing aromatic diamines with pendant diphenyi phosphine oxide group from aromatic diamines prepared from Cashew nut shell liquid (CNSL) to achieve atomic oxygen resistance and space durability for structures made using such monomer as precursor.
Yet another object of the invention is to synthesize new monomers that would find end use in the synthesis of polyamides, polyamide-imides and polyimides and as curing agents for epoxy resins.
Still another object of the invention is to synthesize new monomers from cheap and commercially available renewable resource material like Cashew nut shell liquid.
Summary of the Invention:
The present invention relates to Aromatic bisether diamines having pendant diphenyl-phosphine oxide group of formula (I).

wherein, Ph represent phenyl group; X| and X2 are independently selected from a group of

wherein, R is an alkyl group with at least 8 carbon atoms; and R is either ortho or para to the amine functional group and the two ether linkages on benzene ring are in 1,4 (para to each-other) or 1,3 (meta to each-other) position represented by formula la and la' respectively and the pendant diphenyl phosphine oxide group is ortho to one of the ether linkages.

Novel compounds falling within the general formula are exemplified hereinafter
1. [2, 4-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide.
2. [2, 4-bis-(4'-amino-3'-alkylphenoxy) phenylj-diphenyl phosphine oxide.
3. [2, 4-bis-(6'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide.
4. [2, 4-bis-(6'-amino-3'-alkylphenoxy) phenylj-diphenyl phosphine oxide.
5. [2, 5-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide.
6. [2, 5-bis-(4'-amino-3'-alkylphenoxy) phenylj-diphenyl phosphine oxide.

7. [2, 5-bis-(6'-ammo-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide.
8. [2, 5-bis-(6'-amino-3'-aIkylphenoxy) phenylj-diphenyl phosphine oxide.
This invention also relates to a process for preparing bisether diamines of formula (I).
In a particular embodiment, the inventors have prepared [2, 4-bis-(4'-amino-3'-pentadecyl phenoxy)phenyl-diphenyl phosphine oxide] (ATHDPPO), containing ether linkage, flexible long pendant alkyl group (C15H3]) and phenyl phosphine oxide, for higher flexibility and comparatively lower Tg without sacrificing excellent mechanical and thermal properties of the conventional polyimides. Therefore, the present invention provides arylphosphine oxide derivatives having ether linkage(s), long alkyl groups and phosphine oxide(s) in order to show superior space environment resistant and low dielectric constant without sacrificing excellent properties of polyimides / polyamides.
Detailed Description of invention:

wherein Xi, X2 and Ph are as defined above which have potential application in manufacture of processable polymers required in for example, alignment liquid crystal films. In the compound of formula (I), R is an alkyl group with 8 to 18 carbon atoms; which is primary, secondary or tertiary alkyl, n-pentadecyl; C15 mono-olefinic group, Cis di-olefinic group, C15 tri-olefinic group and any mixture thereof; For example, the most preferred due to its availability in CNSL is the n-pentadecyl (C15H31) group.

The process for preparing bisether diamines of formula (I) comprises the following steps:
1) Subjecting substituted / unsubstituted diphenylphosphinic halide of formula A with
2,4-difluoro bromo-benzene of formula B or 2,5-difluoro bromo-benzene of formula
B' under Grignard reaction conditions to obtain (2,4-diflurophenyl) diphenyl
phosphine oxide of formula 2(a) or (2,5-diflurophenyl) diphenyl phosphine oxide of
formula 2(a')

2) Distilling and hydrogenating commercial cardanol (CNSL) to obtain 3-pentadecyl
phenol; diazotizing or nitrating and reducing the same to 4- or 6-amino-3-
pentadecylphenol of formula 2(b)

3) reacting the compound of formula 2(a) or formula (2a') obtained in Step (1) with 4- or 6-amino-3-pentadecyl phenol of formula 2(b) obtained in Step (2) under reflux, the presence of a base and separating the reaction product and isolating the compound of formula (la) or (la')

Therefore, other compounds of interest may be prepared in the same manner by carrying out the steps with compounds having the desired substituents.
In a particular embodiment of step (1) of the above mentioned process, formula (2a) or formula (2a') is prepared by reacting 2,4-difluoro bromo-benzene of formula (B) or 2,5-difluoro bromo-benzene of formula (2b') with magnesium in tetrahydrofuran or diethyl ether in diphenylphosphinic chloride of formula (A), to obtain the compound (2a) or compound (2a'). A molar ratio of reactants is 1:1 to 1.2:1 (Grignard reagent: diphenylphosphinic chloride) and the reaction is performed at 0-5 °C for 3h and then at room temperature for 24 h. The above reaction mixture is poured in cooled aq. 5% H2SO4.
In particular, diamine monomer of formula la or la' is prepared from nucleophilic substitution reaction of compound (2a) or compound (2a') and compound (2b) in presence of potassium carbonate and a polar aprotic solvent dimethylacetamide (DMAc) by azeotropic distillation with toluene for 6 h at 135'C and finally heated after removal of toluene at 165'C for 16 h. The isolation of the product is done in 5 % acetic acid solution to yield the corresponding compound of formula la or la'.
The synthesis of the diamine is a key feature of this invention. This is prepared from commercially available starting materials in two or more steps with relatively good yield and purity. The intermediates and products formed in each step (l)-(2)-(3) can be isolated by conventional means. These include solvent removal, washing, drying and recrystallization.

This invention further includes a process for preparing a polyimide which comprises reacting 3,3',4,4' benzophenone tetracarboxylic dianhydride with [2,4-bis-(4'-amino-3'-pentadecylphenoxy) phenylj-diphenyl phosphine oxide] in 1:1 stoichiometric ratio and subsequently chemically imidizing the resulting polymer with pyridine in the presence of acetic anhydride and then completing the imidization step by heating the reaction mixture.
This invention further includes polyimides obtained by the above process.
Having generally described the invention, a more complete understanding thereof can be obtained by reference to the following examples that are provided for purposes of illustration only and do not limit the invention in any manner whatsoever to these examples.
Examples
The invented method is described in detail for a particular embodiment of new monomers viz. Diphenyl phosphine oxide containing aromatic diamines represented by Formula (la) and Formula (la').

Example 1
Preparation of [2, 4- bis-(4'-ammo-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine
oxide] (ATHDPPO) (la)
Step 1: Preparation of 2,4-difluoroplienyldiplienylphosphine oxide (2a):
Into a 250 mL three necked round bottom flask equipped with a magnetic stirrer, a thermometer, a nitrogen gas inlet, a pressure equalizing addition funnel and a reflux condenser with drying tube were placed predried magnesium turnings (0.1 mol, 2.43 g) and dry and freshly distilled tetrahydrofuran (THF, 20 mL). The mixture was cooled to -S'C using an ice/water bath. A solution of 2,4-difluoro bromo-benzene (0.1 mol, 19.4 g, 11.36 mL) (B) in THF (40 mL) was placed in the pressure equalizing addition funnel and added drop wise over a period of 1 h. The reaction is initiated with some Iodine crystals, effervescence began as reaction continues. The mixture was allowed to warm to room temperature. The mixture was stirred at room temperature for 3 h and the flask was subsequently placed in the ice/water bath to cool the solution to "S'C. 20% molar excess of above Grignard reactant was taken for the reaction. A solution of diphenylphosphinic chloride (0.083 mol, 19.588 g) (A) in THF (25 mL) was added drop wise over a period of 1 h. The reaction mixture was allowed to warm to room temperature and was stirred under nitrogen for 24 h. The resultant brown solution was poured into 5% H2SO4 solution (250 mL) and the THF layer washed with saturated solution of NaHCOj and the solvent removed after drying over anhydrous sodium sulphate. Finally the residue was distilled under reduced pressure (175'C / 10 mm) to yield the product; which was washed with hexane to remove oily part. Yield (2a) is 16 g (61.39 %). m.p. 89-90'C.; crystallization from mixture of toluene and hexane (1:1) gave white solid 15.6 g (60 % yield) having m.p. IITC. (Lit. m. p. 111.2-111.3 "C).
Step 2: Syntliesis of 4-aniino-3-pentadecylplienol (2b)
a) Commercial cardanol; obtained from CNSL; was distilled under vacuum at 190-220'C / 5 mm of Hg, to give pale-yellow cardanol. Redistilled cardanol was hydrogenated at 70'C in

the pressure autoclave (600 psi pressure / VO'C) using Rainy-Ni catalyst to give 3-pentadecylphenol. (Also known as Tetrahydroanacardol-THA)
b) 4-Amino-3-pentadecylphenol was synthesized from diazonium salt of sulphanUic acid and 3-pentadecylphenol by forming diazonium salt in basic conditions at low temperature; which was reduced with sodium dithionite at about 75 "C to yield the desired araino-phenol, (4-amino-3-pentadecylphenol, also known as 4-amino-tetrahydroanacardol- ATHA); derived from renewable raw material.
3-pentadecyl phenol (0.025 mol, 7.5 g), dissolved in KOH (0.0687 mol, 3.9 g) and 50 mL 95% ethyl alcohol were placed in one liter three necked round bottom flask fitted with a stirrer, a thermometer and a reflux condenser and cooled to -SC. To this diazonium salt, prepared as below, was added.
(A) In 250 mL beaker sulphanilic acid (0.03 mol, 5.25 g), 50 mL water were placed and to this anhyd. NaaCOa (0.0125 mol, 1.325 g), was added with stirring till effervescence disappear. The mixture was warmed to get clear solution and it was then cooled to 0'C.
(B) In another beaker sodium nitrite (NaN02) (0.027 mol, 1.85 g) was dissolved in 10 mL water and cooled to 0°C. Then cooled sodium nitrite solution was added to cooled solution (A) and this mixed solution was immediately added to beaker containing 5.1 mL cone. HCl and 15 g ice. Light pink solid precipitated out. It was allowed to settle (liquid was drained out slowly leaving solid; diazonium salt of sulphanilic acid; behind). To this solid 25 mL cold ethanol was added and the suspension was added to alkaline solution of 3-pentadecyl phenol.
The resulting red-dye solution was stirred for 2 h in ice bath and then stirred at room temperature for 1 h. The red solution was heated with stirring to 60-65'C and a solution of sodium dithionite (11.25 g in 25 mL water) was added. Colour of reaction mixture slowly changed from dark red to pale tan, indicating completion of reduction. A solution of 4 mL glacial acetic acid in 30 mL water was added and reaction mixture was refluxed for 1 h. The

contents of the flask were cooled, when crude 4-amino 3-pentadecyl phenol (2b) separated. The product was filtered off and washed with plenty of water (till filtrate became colourless) and the product was recrystallized from ethanol. Yield 5 g (63 %) ra.p. lOS-lOe'C (Lit m.p. 105°C).
Step 3: Preparation of [2,4-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide (ATHDPPO) (la):
Into a 100 mL three necked round bottom flask equipped with a magnetic stirrer, a thermometer and a Dean-Stark trap equipped with a drying tube were placed 2, 4-difluorophenyldiphenylphosphine oxide (2a) (0.006 mol, 1.88 g), 4-amino-3-pentadecylphenol (2b) (0.012 mol, 3.83g), potassium carbonate (0.0144 mol, 1.98 g, 20% molar excess), N, N dimethyl acetamide (DMAc) (15 mL) and toluene (35 mL). The mixture was heated to reflux, while removing water via azeotropic distillation. After 6 h, the toluene was removed from the reaction and the residual solution was heated at 165'C, for 16 h. The reaction mixture was cooled to room temperature and the solution was poured into 300 mL of cold water containing 5 % acetic acid with vigorous stirring. A tan solid, obtained after stirring for 45 minutes; was filtered, washed with plenty of water, dried under vacuum at TO'C to afford (la); 4.6 g (84% yield). The solid was recrystallized twice from methanol with charcoal treatment to yield 3.8 g (70% yield) of a light cream solid; m.p. 62-64°C.
The FT-IR spectrum (in CHCI3), of Diamine (la) exhibited characteristic absorptions at 3355 (as characteristic doublet above 3300 cm', -NH2 group), at 1167 (P=0) and at 1240 cm' [ether (Ar-O-Ar)]. The 'H and 'C NMR spectra supported the assigned structure of the compound (la). The 'H NMR (in CDCI3), showed the aromatic protons of the aromatic ring (with amine and aliphatic chain) at 6.25 to 6.72 5 whereas peaks at 7.34 to 7.86 6 are due to the aromatic protons of ring with the P=0 group. The peak at 0.86 (triplet) [the terminal methyl of the aliphatic chain (C15H31)] and peaks at 1.24, 1.51 and 2.16 are assigned to (CH2)i4 aliphatic protons in the C15H31 group. Peak at 3.5 5 is of amino - protons. The C NMR (CDCI3) spectrum of (la); showed eighteen peaks corresponding to different eighteen

aromatic carbons and peaks below 70 ppm were of different aliphatic carbons. DEPT spectrum showed disappearance of aromatic tertiary carbons and CH2 carbons (of the aliphatic chain) were seen as downside of the spectrum (negative side) at 36.65 and 24.71 5.
Similarly preparation of [2,5-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide (la') was performed from (2a'); obtained from 2,5 difluoro bromo-benzene; and (2b).

Example 2
Preparation of Polyimide from 3, 3', 4, 4' benzophenone tetracarboxylic dianhydride (BTDA) and [2, 4'bi$-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide] (ATHDPPO) using 1:1 stoichiometry
Into a 100 mL three-necked round-bottom flask equipped with a magnetic needle, nitrogen gas inlet, and calcium chloride guard tube were placed ATHDPPO (la) (1.0 mmol, 0.912 g) and N-methylpyrrolidone (NMP) (6.2 mL) and the solution was cooled to 0'C in ice bath. To this cold solution, solid 3, 3', 4, 4' benzophenone tetracarboxylic dianhydride (BTDA) (1.0 mmol, 0.322 g) was added in small quantity lots over 1 h and solution was stirred for 3 h at 0°C and for 24 h at room temperature under a nitrogen atmosphere. The viscosity of the reaction mixture increased. Some part of polymerization solution, (poly amic acid), was added into methanol to precipitate poly(amic acid). The remaining polymer solution was chemically imidized by 4 mL of acetic anhydride and 0.5 g of pyridine in 4 mL dry benzene, at room

temperature for 24 h. The polyimide solution was poured into methanol, to precipitate polymer, which was filtered, washed with hot water, methanol and then dried under vacuum at 70C for 6 h to afford a white, powder material. In order to ensure complete imidization, chemical imidization was supplemented by thermal imidization; where in chemical imidized polymer was taken in RB flask and heated step wise for 1 h at 100°C, 1 h at 150'C, 1 h at 200'C and finally at 230°C for 20 min. This process ensured the complete imidization. The overall yield of polyimide (ATHPI-1) was 98%.
The inherent viscosity (rii„h) of poly (amic acid) was measured at 0.5% polymer concentration in DMAc at 30 ± 0.1°C by Ubbelohde viscometer. Polymer had inherent viscosity (riinh) 0.3 dlVg. The polyimides synthesized from the diamine monomer are expected to show better atomic oxygen resistance properties.
While the invention has been illustrated and described in typical embodiments, it is not intended to be limited to the details shown, since various modifications and substitutions can be made without departing in any way from the spirit of the present invention. As such, further modifications and equivalents of the invention herein disclosed may occur to persons skilled in the art using no more than routine experimentation, and all such modifications and equivalents are believed to be within the spirit and scope of the invention as defined by the following claims.
Advantages:
The diamines disclosed here can be used in making classes of high performance polymers; they can be used as coupling agents, cross linking agents, plasticizers etc. And further, such prepared materials are suitable for semiconductor package materials, intermediates for optical fibers, optical materials and adhesives for metals etc. These materials or their derivatives can also be used in surface coatings, paints, lacquers, varnishes; in foundry industry, brake-liners, and as specialty hydrophobic, flexible, water resistant resins / polymers.

WE CLAIM:
1. Aromatic bisether diamines having pendant diphenyl phosphine oxide group of formula (I).

wherein, Ph represent Phenyl group; X1 and X2 are independently selected from a group of

wherein, R is an alkyl group with at least 8 carbon atoms; and R is either ortho or para to the amine functional group and the two ether linkages on benzene ring are in 1,4 (para to each-other) or 1,3 (meta to each-other) position represented by formula la and la' respectively and the pendant diphenyl phosphine oxide group is ortho to one of the ether linkages.
2. The aromatic bisether diamines as claimed in claim 1, wherein the compound is either [2, 4-bis-(4'-amino-3'- alkylphenoxy) phenyl]-diphenyl phosphine oxide or [2, 5-bis-(4'-amino-3'- alkylphenoxy) phenylj-diphenyl phosphine oxide.
3. The aromatic bisether diamines as claimed in claim 1, wherein the compound is either [2, 4-bis-(4'-amino-3'-pentadecylphenoxy) phenylj-diphenyl phosphine oxide or [2, 5-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide.
4. The aromatic bisether diamines as claimed in claim 1, wherein the compound is either [2, 4-bis-(6'-amino-3'-alkylphenoxy) phenylj-diphenyl phosphine oxide or [2, 5-bis-(6'-amino-3-alkylphenoxy) phenylj-diphenyl phosphine oxide.
5. The aromatic bisether diamines as claimed in claim 1, wherein the compound is either [2, 4-bis-(6'-amino-3'-pentadecylphenoxy) phenylj-diphenyl phosphine oxide or [2, 5-bis-(6'-amino-3'-pentadecylphenoxy) phenylj-diphenyl phosphine oxide.
6. A process for preparing aromatic bisether diamines of formula (I)

wherein, Ph represent Phenyl group; X| and X2 are independently selected from a group of

wherein, R is an alkyl group with at least 8 carbon atoms; and R is either ortho or para to the amine functional group and the two ether linkages on benzene ring are in 1,4 (para to each-other) or 1,3 (meta to each-other) position represented by formula la and la' respectively and the pendant diphenyl phosphine oxide group is ortho to one of the ether linkages.

1) subjecting substituted / unsubstituted diphenylphosphinic halide of formula A with 2,4-difluoro bromo-benzene of formula B or 2,5-difluoro bromo-benzene of formula B' under Grignard reaction conditions to obtain (2, 4-diflurophenyl) diphenyl

phosphine oxide of formula 2(a) or (2, 5-diflurophenyl) diphenyl phosphine oxide of formula 2(a') :

2) Distilling and hydrogenating commercial cardanol (CNSL) to obtain 3-
pentadecyl phenol, diazotizing / nitrating and reducing the same to 4- or 6-amino-3-
pentadecylphenol of formula 2(b):

3) reacting the compound of formula 2(a) or formula 2(a') obtained in Step (1)
with 4- or 6-amino-3-pentadecyl phenol of formula 2(b) obtained in Step (2) under
reflux in the presence of a base and separating the reaction product and isolating the
compound of formula (la) or (la').

7. The process as claimed in claim 6, wherein the compound of formula (2b) is 4-amin( 3-pentadecyl phenol and the compound of formula (la) or (la') is

8. The process as claimed in claim 6, wherein the compound of formula (2a) or formula (2a') is isolated by washing with aqueous acid particularly with aqueous sulfuric acid in a concentration of 1% to 20%.
9. The process as claimed in claim 6, wherein the reaction under step 3 is carried out at 120"C to 170°C in the presence of an aprotic solvent selected from polar aprotic solvent like N-methylpyrrolidinone, N, N-dimethylacetaraide, dimethyl sulphoxide, hexamethyl phosphoramide, N, N-dimethyl formamide or mixtures thereof.
10. The process as claimed in claim 6, wherein the reaction under step 3 is carried out in the presence of an alkali selected from Na2C03, K2CO3, NaOH, KOH or a mixture thereof.
11. A process for preparing a polyimide comprising the step of reacting 3, 3', 4, 4' benzophenone tetracarboxylic dianhydride with [2,4-bis-(4'-amino-3'-pentadecylphenoxy) phenyl]-diphenyl phosphine oxide of formula (la) or [2,5-bis-(4'-amino-3'-pentadecylphenoxy) phenylj-diphenyl phosphine oxide of formula (la') in

1:1 stoichiometric ratio and subsequently chemically imidizing the resulting polymer with pyridine in the presence of acetic anhydride and then completing the imidization step by heating the precipitated polymer.
12. A polyimide obtained by a process as claimed in claim 11.

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Patent Number

279815

Indian Patent Application Number

656/CHE/2010

PG Journal Number

05/2017

Publication Date

03-Feb-2017

Grant Date

31-Jan-2017

Date of Filing

11-Mar-2010

Name of Patentee

INDIAN SPACE RESEARCH ORGANISATION

Applicant Address

ISRO HEADQUARTERS,DEPARTMENT OF SPACE, ANTARIKSH BHAVAN, NEW BEL ROAD, BANGALORE 560 094.

Inventors:

#	Inventor's Name	Inventor's Address
1	NOORMAHMAD NABI MALDAR	DEPARTMENT OF CHEMISTRY, SOLAPUR UNIVERSITY, KEGAON, SOLAPUR-413 255
2	MRIDUL MEDHI	DEPARTMENT OF CHEMISTRY, SOLAPUR UNIVERSITY, KEGAON, SOLAPUR-413 255
3	SHANMUGAM PACKIRISAMY	VIKRAM SARABHAI SPACE CENTER, THIRUVANANTHAPURAM-695 022

PCT International Classification Number

C07F 9/53

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA