Title of Invention	A PROCESS FOR THE PREPARATION OF A DYE
Abstract	The present invention relates to a process for the preparation of a dye of formula (1), which comprises diazotising a compound of formula (2), in acid aqueous medium in the temperature range from - 10 to 30 degree C and coupling the diazonium compound so obtained to a coupling component of formula (3), in acid aqueous or aqueous organic medium in the temperature range from -10 to 30 degree C.

Full Text

The present invention relates to a process for the preparation of a dye. Disperse dyes, i.e. dyes which do not contain any water-solubilising groups, have been known for a long time and are used for dyeing hydrophobic textile mateR1als. Often, however, the resultant dyeings are not suffiC1ently fast to thermomigration and some of their properties are also unsatisfactory, in particular their fastness to washing and perspiration. This problem occurs in particular with blue and navy blue shades. This invention relates to disperse dyes with which dyeings are obtained that are very fast to thermomigration as well as to washing and perspiration and which in addition have good build-up in the exhaust and thermosol processes as well as in textile pR1nting. The dyes are also suitable for discharge pR1nting. The novel dyes correspond to formula wherein R is nitro or cyano, R1 is halogen, R2 is C1 -C4alkyl which is unsubstituted or substituted by C1-C3alkoxy, halogen, cyano or phenyl, R3 is C1-C4alkyl, R4 is methyl or ethyl, R5 is hydrogen, methyl or ethyl, and R6 is methyl or ethyl, with the proviso that R5 is not hydrogen if R is nitro, R1 is halogen and R2 is C1 -C4alkyl. Rt defined as halogen is bromo, chloro or iodo. R2 and R3 defined as C1 -C4alkyl are each independently of the other typically methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl and isobutyl. R1 is chloro or bromo. Chloro is preferred. R2 is ethyl or methyl. Methyl is preferred. R3 is ethyl or methyl. Methyl is preferred. R5 is hydrogen or methyl. Methyl is preferred. Accordingly, the present invention also provides a process for the preparation of a dye of formula (1) as claimed in claim 1, which compR1ses diazotising a compound of formula (2) in aC1d aqueous medium in the temperature range from -10 to 30°C and coupling the diazonium compound so obtained to a coupling component of formula (3), wherein R, Rt, R2, R3, R4, R5 and R6 have the meanings given in formula (1) in aC1d aqueous or aqueous organic medium in the temperature range from -10 to 30°C. The diazotisation of the compounds of formula (2) is carR1ed out in per se known manner, for example with sodium nitR1te in aC1d, typically hydrochloR1c or sulfuR1c aC1d, aqueous medium. The diazotisation can, however, also be carR1ed out with other diazotising agents, conveniently with nitrosylsulfuR1c aC1d. The reaction medium of the diazotisation may contain an additional aC1d, typically phosphoR1c aC1d, sulfuR1c aC1d, acetic aC1d, propionic aC1d, hydrochloR1c aC1d or mixtures of these aC1ds, for example mixtures of phosphoR1c aC1d and acetic aC1d. The diazotisation is conveniently carR1ed out in the temperature range from-10 to 3 0°C, preferably from -10°C to room temperature. The coupling of the diazotised compounds of formula (2) to the coupling component of formula (3) is likewise carR1ed out in known manner, conveniently in aC1d, aqueous or aqueous-organic medium, preferably in the temperature range from -10 to 30°C, most preferably be- low 10° C. Suitable aC1ds include hydrochloR1c aC1d, acetic aC1d, sulfuR1c aC1d or phosphoR1c aC1d. Diazotisation and coupling may be typically carR1ed out in the same reaction medium. Some of the diazo components of formula (2) and the coupling components of formula (3) are known or can be prepared in per se known manner. The coupling component of formula (3a), wherein R4 and R6 have the meaning given for formula (1) are novel and are also an object of this invention. The coupling component of formula (3a) is prepared, for example, by reacting 3-amino-4-methoxyacetanilide first with a compound of formula CH3-CHC1-COOR6 and then with a com¬pound of formula CH2C1-COOR4. The novel dyes of formula (1) can be used for dyeing and pR1nting semi-synthetic and, pre¬ferably, synthetic hydrophobic fibre mateR1als, in particular textile mateR1als. Textile mateR1als made from blends that contain such semi-synthetic or synthetic hydrophobic fibre mateR1als can also be dyed or pR1nted with the novel dyes. Suitable semi-synthetic textile mateR1als are in particular cellulose secondary acetate and cellulose tR1acetate. Synthetic hydrophobic textile mateR1als consist pR1maR1ly of linear aromatic polyesters, typi¬cally those of terephthalic aC1d and glycols, espeC1ally ethylene glycol, or of condensates of terephthalic aC1d and 1,4-bis(hydroxymethyl)cyclohexane; of polycarbonates, typically those of a,a-dimethyl-4,4"-dihydroxydiphenylmethane and phosgene, or of fibres based on poly¬vinyl chloR1de and polyamide. The novel dyes are applied to the textile mateR1als by known dyeing methods. Typically, poly¬ester fibre mateR1als are dyed from an aqueous dispersion by the exhaust process in the presence of customary anionic or nonionic dispersants and in the presence or absence of customary swelling agents (carR1ers) in the temperature range from 80 to 140°C. Cellulose secondary acetate is preferably dyed at a temperature from about 65 to 85°C, and cellulose tR1acetate at temperatures of up to 115° C. The novel dyes do not stain wool and cotton simultaneously present in the dyebath or effect only minor staining (very good resist), so that they can also readily be used for dyeing poly¬ester/wool and polyester/cellulose blends. The novel dyes are suitable for dyeing by the thermosol process, for exhaust and continuous processes and for pR1nting. The exhaust dyeing process is preferred. The liquor ratio depends on the apparatus used, on the substrate and on the form of presentation. However, it may be chosen from a wide range, e.g. from 1:4 to 1:100, but is preferably from 1:6 to 1:25. The C1ted textile mateR1al can be in any form of presentation, such as fibre, thread or non-woven fabR1c, or wovens or knitgoods. It is expedient to convert the novel dyes, before use, into a dye formulation. This is done by milling the dye to an average particle size of 0.1 to 10 micron. Milling can be carR1ed out in the presence of dispersants. Typically, the dR1ed dye is milled with a dispersant, or kneaded in paste form with a dispersant, and thereafter dR1ed under vacuum or by spray drying. PR1nting pastes and dyebaths can be prepared by adding water to the formulations so obtained. This invention also relates to dye formulations, which compR1se a) as dye component 30 to 50 % by weight, based on the total weight of the dye formulation, of a dye of formula (1), wherein R is nitro or cyano, R, is halogen, R2 is CrC4alkyl which is unsubstituted or substitu¬ted by C1-C3alkoxy, halogen, cyano or phenyl, R3 is C1-C4alkyl, R4 is methyl or ethyl, R5 is hydrogen, methyl or ethyl, and R6 is methyl or ethyl, and b) 50 to 70 % by weight, based on the total weight of the dye composition, of a dispersant. Suitable dispersants are, for example, anionic dispersants, such as aromatic sulfonic aC1d/formaldehyde condensates, sulfonated creosote oil/formaldehyde condensates, lignin sulfonates or copolymers of acrylic aC1d deR1vatives and of styrene deR1vates, preferably aromatic sulfonic aC1d/formaldehyde condensates or lignin sulfonates, or nonionic dispersants based on polyalkylene oxides obtainable, for example, by polyaddition reaction from ethylene oxide or propylene oxide. The dye formulations of this invention are preferably solid. The novel dye formulations are distinguished by being readily convertible into the form in which they can be applied, for example into the finished pR1nting paste or dye baths. The customary thickeners will be used for pR1nting, for example modified or unmodified natu¬ral products, typically alginates, BR1tish gum, gum arabic, crystal gum, carob bean gum, tra-gacanth, carboxymethylcellulose, hydroxyethylcellulose, starch or synthetic products, typi¬cally polyacrylamides, polyacrylic aC1ds or their copolymers, or polyvinyl alcohols. The novel dyes impart to the C1ted mateR1als, espeC1ally to the polyester mateR1al, level blue to navy blue shades of very good end-use properties, such as good fastness to light and sublimation. To be mentioned in particular is the excellent fastness to washing and perspiration and, espeC1ally, to thermomigration. The novel dyes are furthermore distinguished by good exhaustion and build-up. The novel dyes can also be very well used for the preparation of mixed shades with each other or also together with other dyes. This invention relates to the above-mentioned uses of the novel dyes as welt as to a process for dyeing or pR1nting semi-synthetic or synthetic hydrophobic fibre mateR1al, in particular tex¬tile mateR1al, which process compR1ses applying to, or incorporating into, the C1ted mateR1al one or more than one of the novel dyes. The C1ted hydrophobic fibre mateR1al is preferably textile polyester mateR1al. Other substrates which can be treated with the process of this in¬vention as well as preferred process conditions are to be found above in the detailed descR1ption of the use of the novel dyes. In another of its aspects, this invention relates to the hydrophobic fibre mateR1al, preferably polyester textile mateR1al, dyed or pR1nted by the C1ted process. The novel dyes of formula (1) are also suitable for modern recording processes such as thermotransfer pR1nting. The invention is illustrated by the following Examples. Unless otherwise stated, parts and percentages are by weight and the temperatures are given in degrees Celsius. The rela¬tionship between parts by weight and parts by volume is the same as that between the gramme and the cubic centimetre. Example 1: In a reaction flask, 60.0 parts by weight of 3-amino-4-methoxyacetanilide are added to 200 parts by weight of methyl chloroacetate at a temperature from 20 to 30° C. To this mix¬ture are then added 60 parts by weight of sodium carbonate. The resulting suspension is evenly heated, with constant stirR1ng, to 115° C and is kept for 6 hours at this temperature. After the reaction is complete, the mixture is cooled to room temperature, charged with 330 parts by weight of water and stirred for 30 minutes until the salts are completely dissol¬ved. After being stood for a short peR1od, 2 phases form in the reaction flask. The lower, or¬ganic, phase is isolated and excess methyl chloroacetate is removed therefrom by distillation in a rotary evaporator. This gives 105 parts by weight of the compound of formula (10) in the form of a resinous residue which is then dissolved in 195 parts by weight of acetic aC1d. Example 2: In a reaction flask, 72.6 parts by weight of 2-amino-3-bromo-5-nitrobenzonitR1le are dissolved in 107 parts by weight of 98% sulfuR1c aC1d at a maximum temperature of 35° C. 104 parts by weight of 40% nitrosylsulfuR1c aC1d are added dropwise over 40 minutes to this reaction mix¬ture which is then stirred for 120 minutes at 25° C. The resultant diazo solution is then added dropwise to 300 parts by weight of the 35% solution of the coupling component of Example 1 and to 200 parts by weight of ice over 60 minutes at 0 to 5° C, the reaction temperature being kept at a maximum of 5° C by addition of ice. After addition of the diazo solution is complete, the mixture is stirred for 2 hours, the temperature R1sing to 20° C. The resultant preC1pitate is collected by filtration, washed with water and dR1ed, giving 153 parts by weight of a dye of formula (100) which dyes polyester textile mateR1al in a blue shade having good fastness properties, in particular good fastness to thermomigration and washing. Examples 3 - 22: The dyes of formulae (101) to (120) listed in Table 1 can be prepared in general analogy to the instructions of Example 2. They also dye polyester textile mateR1al in navy blue and blue shades having good fastness properties, in particular good fastness to thermomigration and washing. The preferred dyes are those of formulae (101) to (108), (110) to (113) and (117) to (120). Particularly preferred dyes are those of formulae (106), (108), (110), (117) and (119). WE CLAIM; 1. A process for the preparation of a dye of formula (1) (1). wherein R is nitro or cyano, R1 is halogen, R2 is C1-C4alkyl which is unsubstituted or substituted by C1-C3alkoxy, halogen, cyano or phenyl, R3 is C1-C4alkyl, R4 is methyl or ethyl, R5 is hydrogen, methyl or ethyl, and Rg is methyl or ethyl, with the proviso that R5 is not hydrogen if R is nitro, R1 is halogen and R2 is C1-C4alkyl, which comprises diazotising a compound of formula (2) in aC1d aqueous medium in the temperature range from -10 to 30° C and coupling the diazonium compound so obtained to a coupling component of formula (3). wherein R, R1, R2, R3, R4, R5 and R6 have the meanings given for formula (1), in aC1d aqueous or aqueous organic medium in the temperature range from -10 to 30° C. 2. The process according to claim 1, wherein R1 is chloro or bromo. 3. The process according to claim 1 or claim 2, wherein R2 is ethyl or methyl. 4. The process according to anyone of claims 1 to 3, wherein R3 is ethyl or methyl. 5. The process according to anyone of claims 1 to 4, wherein R5 is hydrogen or methyl. 6. The process according to claim 5, wherein R5 is methyl. 7. The process according to claim 1, wherein R is cyano, Ri is chloro or bromo, R2 and R3 are each independently of the other methyl or ethyl, R4 is methyl or ethyl, R5 is methyl, and R6 is methyl or ethyl.

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