Indian Patents. 215720:"AN IMPROVED PROCESS FOR THE PREPARATION OF ALKALINE EARTH METAL ALKYL ARYL SULFONATES USEFUL AS RUST PREVENTIVES"

Title of Invention	"AN IMPROVED PROCESS FOR THE PREPARATION OF ALKALINE EARTH METAL ALKYL ARYL SULFONATES USEFUL AS RUST PREVENTIVES"
Abstract	The present invention reports an improved process for the preparation of alkaline earth metal alkyl aryl sulfonates useful as temporary rust preventives which comprises sulfonation of heavy alkyl benzene fraction selected from boiling range 400 - 500°C with sulfuric acid concentration in the range of 90-105% and temperature of sulfonation being maintained in the range of 10 - 150" C .

Full Text	This invention relates to an improved process for the preparation of alkaline earth metal alkyl aryl sulfonates useful as rust preventives. The process of the present invention particularly relates to the prepartion of calcium and magnesium alkyl benzene sulfonates of molecular weight range 940 - 1040 and base no. 50-150 from selective heavy alkyl benzene fractions of molecular weight range 370-430 as additive components for temporary rust preventive formulations for ferrous metal parts. Alkaline earth metal sulfonates when blended in a hydrocarbon lubricant of viscosity 7 to 15 centistrokes at 100°C in concentration of 2 to 10 percent act as rust preventives for ferrous metal parts in presence of saline water, sea water and in acidic environment when applied in sufficient quantities on their surface with a brush or preferably by dipping the metal parts in the rust preventive oil solution for atleast half hour. Magnesium and calcium alkyl aryl sulfonates have usually been prepared by reacting the corresponding sodium sulfonate with calcium or magnesium halides/ nitrates. Some recent processes, however, describe preparation of calcium and magnesium sulfonates by direct neutralisation of alkyl aryl sulfonic acids followed by raising of the base numbers by peptization of metal base by a number of techniques. Reference may be made to Belgian Patent BE 905 530 wherein magnesium oxide is reacted with alkyl benzene sulfonic acid in presence of methanol xylene and heptane and mineral oil at 55 - 56°C with carbondioxide under pressure giving a very high base number of the material in another Belgium patent Be 905, 532 the sulfonic acid is reacted with calcium oxide in mineral oil with ammonium carbonate in presence of methanol and xylene additionally passing carbondioxide at elevated temperatures for one hours and ten minutes and in another patent application BE 905, 533 calcium glutamate sulfonate complex is similarly produced. In yet another reference PCT appl. WO 88 07 073 ammonium hydroxide is used in addition to carbondioxide solvents and lubricants. The use of carboxylic acids, amino acids, ammonium carbonate and carbondioxide under pressure and at elevated temperature are both cost and energy intensive. Since the material is not centrifuged the trace inorganic impurities affect the rust inhibiting performance. Excessive base numbers do not enhancer the performance of rust inhibitors except under the acidic environment but create complications in the formulations for temporary rust preventives containing other performance enhances such as tackyness agents, sorbitan carboxylates and metal passivators. The other draw backs are alkaline earth metal derivatives prepared by these methods mostly meet the molecular weight requirements but not the narrow molecular weight spread such derivatives generally possess only moderate rust preventive characteristics. The main object of the present invention is to provide an improved process for the preparation of alkaline earth metal alkyl aryl sulfonates useful as rust preventives which obviates the draw back of the hitherto known processes. Another object of the present invention is to provide an improved process to overbase the alkaline earth metal sulfonates to a base number in excess of 100. Yet another object is to provide an improved process wherein the characteristics of alkaline earth metal sulfonates useful as rust inhibitors are given in table 1 below. Table- I (Table Removed) Accordingly the present invention provides an improved process for the preparation of alkaline earth metal alkyl ulfonates useful as temporary rust preventives which comprises sulfonation of heavy alkyl benzene fraction selected from boiling range 400 - 500°C with sulfuric acid concentration in the range of 90-105% and the amount of sulfuric acid being in the range from 1 to 5 times the weight of heavy alkyl benzenes fraction and temperature of sulfonation being maintained in the range of 10 - 150°C whereby water and sludge formed during said sulfonation and wherein the alkyl benzene sulfonic acid (sour oil) being separated from sulfonate acid mixture by settling at a temperature ranging 20 - 100°C for a period ranging 4-24 hours followed by neutralization with alkaline earth oxide/ hydroxide of mesh size of ab^af 200 and the said oxide/hydroxide used being in the form of slurry of the concentration ranging from 10-20% at a temperature ranging 30-80°C. to ph 7 to 8, separating the alkaline earth sulfonate from neutralized mass by extraction with an aromatic solvent by conventional methods, removing thesaid aromatic solvent by distillation to obtain neutral alkaline earth metal alkyl aryl sulfonate which is over based by peptizing alkaline earth metal base and the ratio of the said sulfonate and that of the alkaline earth metal base being kept in the range of 4:1 to 1:2 and by passing carbon dioxide in presence of C1to C10 aliphatic ketone and C1to C6 alcohols ^> removing the solvents and redissolving contents in an aromatic solvent and centrifuging it to obtain a transparent solution from which solvent being removed to obtain basic alkaline earth metal alkyl aryl sulfonate . In another embodiment of the present invention the temperature of sulfonation is maintained between 50 - 80°C. In yet another embodiment of the present invention the neutralization of sour oil is carried out with alkaline earth oxide or hydroxide in a 10 to 50 percent slurry in temperature range 30-80°C In still another embodiment of the present invention the neutralized sour oil is diluted with an aromatic solvent by 2 to 20 times of its volume and centrifuged at 2000 - 10,000 rpm for 0.25 to 10 hours to separate neutral alkaline earth alkyl aryl sulfonate solution from solid inorganic impurities. The concentration of neutral alkaline earth sulfonate solution in hydrocarbon may be reduced to 20 to 60 percent by dilution with hydrocarbon oil before overbasing. The neutral alkaline earth sulfonate may be treated with alkaline earth base such as oxide/ hydroxide such that sulfonate : calcium/ magnesium oxide/ hydroxide ratio is between 4:1 to 1:2. The calcium/ magnesium oxide/ hydroxide used may have a particle size below 100 to 350 mesh preferably below 200 mesh and activated with a short chain alcohol from among methanol to butanol. The mixture of neutral calcium magnesium sulfonate and activated calcium/ magnesium oxide/ hydroxide may be diluted with 1 to 4 times of its volume with aromatic solvent and an aliphatic ketone as promoter such that aromatic solvent to aliphatic ketone ratio is 20 : 1 to 1: 1. The reaction mixture in the above claim may be reacted with carbon dioxide such that molar ratio of calcium/ magnesium oxide or hydroxide to carbondioxide varies between 1 : 1 to 4: 1. The said moles of carbondioxide may be bubbled between 2 to 20 hours preferably between 3 to 8 hours at temperatures between 5 to 80°C. The aromatic solvent, the aliphatic ketone and short chain alcohol may be removed by distillation while raising temperature between 100 - 150°C. The remaining contents after distillation may be diluted with aromatic solvent by 2 to 15 times by weight and kept undisturbed for 1 to 8 hours. The supernatant aromatic solvent may be centrifuged at 2000 - 8000 rpm for 0.25 to 5 hours. The process of present invention is accomplished by sulfonation with sulfuric acid in a single shot to obtain alkyl aryl sulfonic acids in requisite concentration to obtain calcium and magnesium sulfonates of required concentration. Unlike other processes sulfonation with sulfurtrioxide and oleum is avoided such that no prior dilution is needed with an inert solvent. In an embodiment of the process present invention involves preparation of basic calcium alkyl aryl sulfonates useful as rust inhibitors of out standing rust inhibiting quality from heavy alkyl benzenes such that no rust appears upto 300 hours when evaluated in 3 percent concentration in a mineral oil in a humidity cabinet by ASTM D-1748-83 rust test as compared to 72 hours with mineral oil alone and upto 200 hours with neutral calcium alkyl aryl sulfonates from the same source. These sulfonates act as excellent rust inhibitors in saline water conditions as well as in acidic and corrosive environment. In the process of present invention heavy alkyl benzenes boiling range 230 - 458°C and 230 - 500°C respectively are subjected to fractional distillation under vacuum to remove lighter cuts boiling upto 400°C. The heavier fractions boiling between 410°C - 458°C and 418 - 500°C respectively are sulfonated with sulfuric acid (98 - 104%) with constant stirring. The sulfonated oil is separated from the spent acid layer and neutralized with a 30 percent slurry of calcium hydroxide/ magnesium hydroxide till pH 9 to 10. The neutralized sulfonic acid is separated from rest of the inorganic impurities by dissolving in an aromatic hydrocarbon and centrifuging at 2000 - 5000 rpm for 0.25 to 5 hours. The aromatic hydrocarbon is distilled off and the calcium magnesium alkyl benzene sulfonate is dried under vacuum to remove the remaining solvent. Calcium/ magnesium sulfonate contains between 70 - 85 percent sulfonate and rest of it is unreacted hydrocarbon. Water content and inorganic salt falls between the measurable range. The base no. varies between 10 to 25 mg. KOH/g. Neutral calcium/ magnesium sulfonate is diluted with mineral oil to bring down the concentration of sulfonate to a level of 40 - 60 percent. The sulfonate is diluted with toluene and an aliphatic ketone and treated with a 2.5 - 10 percent slurry of calcium oxide activated with anhydrous aliphatic alcohol. Carbon dioxide is bubbled such that it is 0.5 to 1.5 times the stiochiometric amount required to form metal carbonate over a period of 2 to 8 hours. The aliphatic alcohol, ketone and toluene is removed by distillation and the contents are heated upto 150°C cooled and diluted with an aromatic solvent. Supernatant liquid is centrifuged at 2000 - 5000 rpm for 0.25 to 5 hours. Aromatic solvent is removed from centrifbged solution by distillation. The basic calcium/ magnesium sulfonate so obtained had nearly 2 to 4 times excess metal than the stiochiometric amount, remained transparent and stable for shelf life of more than six months. It had a base number between 80 - 150 mg KOH/g. The rate of addition of sulfuric acid to heavy alkyl benzene and the speed of stirring should be between 5-50 g/min. and 900 ± 50 rpm respectively such that temperature of sulfonation is controlled between 50-80°C. The quantity of sulfuric acid : heavy alkyl benzene should between 1 to 3:1 by weight and concentration of sulfuric acid should not fall below 94% by weight. The particle size of calcium oxide/ hydroxide/ carbonate used in peptizing process for overbasing of the sulfonate should not be above 200 - 300 mesh and it must be activated with an alcohol boiling below 80°C. The temperature at which carbon dioxide is bubbled should be in the range 0 - 70°C and rate of bubbling should lie between 10.8 g/ hour to 30 gm/ hour per 1000 gm of sulfonate. The following examples are given by way of illustration and should not be construed to limit the scope of the present invention : Example 1: 1000 gm of heavy alkyl benzene fraction boiling between 410-480°C was taken in flask fitted with a stirrer and thermometer. 1500 gm of 98% sulfuric acid was added drop wise at the rate of 25 gm/ min. to heavy alkyl benzene with stirring at 1000 rpm. The temperature was raised to 60+5°C. The reaction continued for one hour. The contents were diluted with 1000 ml of water and 1000 ml of an aromatic solvent and neutralized with 500 gm of calcium oxide made into a slurry with 1000 ml of water to pH 9.5. 4 litres aromatic solvent was added and content heated to 80°C with stirring and allowed to settle for 10 minutes. The supernatant liquid was centrifuged at 1500 rpm for 3 hours. The centrifuged liquid was treated with 200 ml of an aliphatic ketone b.pt. 114°C. 220 gm of calcium oxide of particle size smaller than 100 mesh size activated with 800 ml of an aliphatic alcohol boiling at 65°C. 60 litres of carbondioxide (pressure 2-3 atmospheres) is bubbled through the content for 2 hours. The temperature increased from 40 to 43°C. The aliphatic alcohol is recovered at 65 - 70°C and aromatic solvent and ketone above 80°C. The stirring continued for 2 hours at 140°C. The contents are diluted with 5 litres of aromatic solvent centrifuged at 3000 rpm for one hour. The solvent is distilled off to obtain a product of base no. 150 and percentage of calcium is 4.95. Evaluation of the rust inhibiting properties in a 3% concentration in a 500 neutral mineral oil show that first rust spot appeared after 300 hours. Example 2: 1000 gm. of heavy alkyl benzene fraction 420 - 500°C is taken in a flask fitted with a stirrer and thermometer. 800 gm. of 105% sulfuric acid (5% SOs) is added dropwise at the rate 15 gm./ min. to heavy alkyl benzene with stirring at 1000 rpm. The temperature is maintained at 45 + 5°C. The reaction continued for one hour after addition of all the sulfuric acid. The contents are diluted with 1000 ml. of an aromatic solvent and neutralised with 500 gm. of magnesium hydroxide made into slurry with 1.5 litres of water to pH 9.10 litres of aromatic solvent is added and contents are heated to 60°C with stirring and allowed to settle for 2 hours. The supernatant liquid is treated with 500 ml. of an aliphatic ketone b.pt. 78°C, 400 gm. of magnesium hydroxide of particle size smaller than 300 mesh activated with 1000 ml of an aliphatic alcohol boiling point 65°C. 40 litres of carbondioxide (pressure 5 atmospheres) is bubbled through the the contents over a period of 5 hours. The temperature is maintained at 25°C. The aliphatic alcohol, aromatic solvent and ketone were recovered by distillation. The stirring is continued for two hours while the temperature is raised to 130°C. The contents are diluted with 5 litres of an aromatic solvent and centrifuged at 4000 rpm for 3 hours. The aromatic solvent is removed by distillation and the remaining solvent removed from overbase magnesium alkyi benzene sulfonate. The sulfonate content is 52%, magnesium percentage is 4.8 and base no. is 182. A 4 percent blend of this sulfonate in a 500 neutral mineral base oil showed appearance of first rust spot after 240 hours in the ASTM humidity cabinet rust test. Example 3 : 1000 gm. of an heavy alkyl benzene fraction boiling between 420 - 500°C is sulfonated with 1000 gm. of the 100% sulfuric acid as per the conditions of sulfonation described in example 2. The contents of reaction are diluted with 1000 ml. of water and 1000 ml. of aromatic solvent boiling range 110 - 140°C and neutralized with 500 gm. of powdered lime passing through 200 mesh sieve to pH 9. 15 litres of aromatic solvent is added with stirring and allowed to settle for 6 hours. The supernatant liquid is centrifuged at 3000 rpm. for one hour. The centrifuged liquid is treated with 500 ml. of an aliphatic ketone boiling point 114°C. 400 gm. of calcium hydroxide of particle size smaller then 300 mesh is activated with 1000 ml. of an aliphatic alcohol boiling point 65°C. 40 litres of carbondioxide (pressure 2-3 atmospheres) is bubbled through the content over a period of 5 hours. The temperature is maintained at 20-25°C. The aliphatic alcohol, aromatic solvent and the ketone is removed by distillation while the temperature is raised to 125°C and maintained for one hour. The contents are diluted with 8 litres of aromatics solvent and centrifuged at 4000 rpm for one hour. The centrifuged liquid is distilled to remove aromatic solvent to obtain calcium alkyl aryl sulfonate which is vacuum dried. The base number of the sulfonate is 250, the calcium content is 8.62 and the first rust spot appears after 280 hours when a 3 percent blend in 500 neutral mineral oil is evaluated by ASTM D 1748-83 rust test in humidity cabinet. The main advantages of the process are : 1. Sulphuric acid 90 - 105% may be used instead of sulfur trioxide or oleum for sulfonation and temperature of sulfonation may be between 50 - 80°C. 2. The sour oil separated from the spent acid may be neutralised with alkaline earth oxide/ hydroxide/ hydroxide in a 10 to 50 percent slurry and the neutral alkaline earth metal sulfonate may be recovered directly by solvent extraction and centrifuging at 2000 - 10,000 rpm. 3. The neutral calcium sulfonate may be overabased with alkaline earth metal oxide activated with an alcohol such that ratio sulfonate to alkaline earth metal oxide may be 4:1 to 1:2. 4. The alkaline earth metal oxide/ hydroxide may have a particle size below 200 mesh and may be peptised in presence of hydrocarbon oil, solvent and promoter such as aliphatic ketone by passing carbondioxide between 3 to 8 hours at 5 to 80°C. 5. The solvent to may be recovered by distillation and a stable clear transparent dispersion of alkaline earth metal base in sulfonate may be obtained. 6. The basic alkaline earth sulfonate obtain may be used as a rust preventive. We Claim: 1. An improved process for the preparation of alkaline earth metal alkyl aryl sulfonates useful as temporary rust preventives which comprises sulfonation of heavy alkyl benzene fraction selected from boiling range 400 - 500°C with sulfuric acid concentration in the range of 90-105% and the amount of sulfuric acid being in the range from 1 to 5 times the weight of heavy alkyl benzenes fraction and temperature of sulfonation being maintained in the range of 10 - 150°C whereby water and sludge formed during said sulfonation and wherein the alkyl benzene sulfonic acid (sour oil) being separated from sulfonate acid mixture by settling at a temperature ranging 20 - 100°C for a period ranging 4- 24 hours followed by neutralization with alkaline earth oxide/ hydroxide of mesh size of about 0 200 and the said oxide/hydroxide used being in the form of slurry of the concentration ranging from 10-20% at a temperature ranging 30- 80°C to pH 7 to 8, separating the alkaline earth sulfonate from neutralized mass by extraction with an aromatic solvent selected from benzene , toluene by conventional methods, removing the said aromatic solvent by distillation to obtain neutral alkaline earth metal alkyl aryl sulfonate which is over based by peptizing alkaline earth metal base and the ratio of the said sulfonate and that of the ( alkaline earth metal base being kept in the range of 4:1 to 1:2 and by passing carbon dioxide in presence of C1to C10aliphatic ketone and C1toC6 alcohol Removing solvents and redissolving contents in an aromatic solvent such as herien described the range of claim and centnfuging it to obtain a transparent solution from which solvent being removed to obtain basic alkaline earth metal alkyl aryl sulfonate . 2. An improved process as claimed in claim 1, wherein the temperature of sulfonation is maintained between 50 - 80°C. 3. An improved process as claimed in claim 1- 2, wherein the neutralization of sour oil is carried out with alkaline earth oxide or hydroxide in a 10 to 50 percent slurry in the temperature range 30 -80°C. 4. An improved process as claimed in claim 1- 3 , wherein the neutralized sour oil is diluted with an said aromatic solvent by 2 to 20 times of its volume and centrifuged at 2000 - 10,000 rpm for 0.25 to 10 hours to separate neutral alkaline earth alkyl aryl sulfonate solution from solid inorganic impurities. 5. An improved process as claimed in claim 1- 4, wherein the concentration of neutral alkaline earth sulfonate solution in hydrocarbon is reduced to 20 to 60 percent by dilution with hydrocarbon oil before over basing. 6. An improved process as claimed in claims 1 to 5, wherein the neutral alkaline earth sulfonate is treated with alkaline earth base such as oxide/ hydroxide such that sulfonate: calcium/magnesium oxide/hydroxide ratio is between 4:1 to 1:2. An improved process as claimed in claim 1- 6, wherein the calcium/ magnesium oxide/ hydroxide used had a particle size below 350 the cope mesh preferably below 200 mesh and activated with a short chain, alcohol from among methanol to butanol. 8. An improved process as claimed in claim 1- 7, wherein the mixture of neutral calcium magnesium sulfonate and activated calcium/ magnesium oxide/ hydroxide is diluted with 1 to 4 times of its volume with aromatic solvent and an aliphatic ketone as promoter such that aromatic solvent to aliphatic ketone ratio is 20: 1 to 1:1. 9. An improved process as claimed in claim 1- 8, wherein the reaction mixture in the above claims is reacted with carbon dioxide such that molar ratio of calcium/magnesium oxide or hydroxide to carbon dioxide varies between 1:1 to 4:1. 10. An improved process as claimed in claim 1- 9, wherein the said moles of carbon dioxide is bubbled between 2 to 20 hours preferably between 3 to 8 hours at temperatures between 5 to 80°C. 1 l.An improved process as claimed in claim 1-10 , wherein the aromatic solvent, the aliphatic ketone and; short chain alcohol is removed by distillation while raising temperature between 100 -150 C not 12. An improved process as claimed in claim 1-11, wherein the remaining contents after distillation is diluted with aromatic solvent by 2 to 15 times by weight and kept undisturbed for 1 8 hours. 13. An improved process as claimed in claim 1-12, wherein the supernatant aromatic solvent is centrifuged at 2000 - 8000 rpm fro 0.25 to 5 hours. 14.An improved process for the preparation of alkaline earth metal alkyl aryl sulfonates useful as rust preventives substantially as herein described with reference to the examples.

Full Text

This invention relates to an improved process for the preparation of alkaline earth metal alkyl aryl sulfonates useful as rust preventives.
The process of the present invention particularly relates to the prepartion of calcium and magnesium alkyl benzene sulfonates of molecular weight range 940 - 1040 and base no. 50-150 from selective heavy alkyl benzene fractions of molecular weight range 370-430 as additive components for temporary rust preventive formulations for ferrous metal parts.
Alkaline earth metal sulfonates when blended in a hydrocarbon lubricant of viscosity 7 to 15 centistrokes at 100°C in concentration of 2 to 10 percent act as rust preventives for ferrous metal parts in presence of saline water, sea water and in acidic environment when applied in sufficient quantities on their surface with a brush or preferably by dipping the metal parts in the rust preventive oil solution for atleast half hour.
Magnesium and calcium alkyl aryl sulfonates have usually been prepared by reacting the corresponding sodium sulfonate with calcium or magnesium halides/ nitrates. Some recent processes, however, describe preparation of calcium and magnesium sulfonates by direct neutralisation of alkyl aryl sulfonic acids followed by raising of the base numbers by peptization of metal base by a number of techniques.
Reference may be made to Belgian Patent BE 905 530 wherein magnesium oxide is reacted with alkyl benzene sulfonic acid in presence of methanol xylene and heptane and mineral oil at 55 - 56°C with carbondioxide under pressure giving a very high base number of the material in another Belgium patent Be 905, 532 the sulfonic acid is reacted with

calcium oxide in mineral oil with ammonium carbonate in presence of methanol and xylene additionally passing carbondioxide at elevated temperatures for one hours and ten minutes and in another patent application BE 905, 533 calcium glutamate sulfonate complex is similarly produced.
In yet another reference PCT appl. WO 88 07 073 ammonium hydroxide is used in addition to carbondioxide solvents and lubricants.
The use of carboxylic acids, amino acids, ammonium carbonate and carbondioxide under pressure and at elevated temperature are both cost and energy intensive. Since the material is not centrifuged the trace inorganic impurities affect the rust inhibiting performance. Excessive base numbers do not enhancer the performance of rust inhibitors except under the acidic environment but create complications in the formulations for temporary rust preventives containing other performance enhances such as tackyness agents, sorbitan carboxylates and metal passivators.
The other draw backs are alkaline earth metal derivatives prepared by these methods mostly meet the molecular weight requirements but not the narrow molecular weight spread such derivatives generally possess only moderate rust preventive characteristics.
The main object of the present invention is to provide an improved process for the preparation of alkaline earth metal alkyl aryl sulfonates useful as rust preventives which obviates the draw back of the hitherto known processes.

Another object of the present invention is to provide an improved process to overbase the alkaline earth metal sulfonates to a base number in excess of 100.
Yet another object is to provide an improved process wherein the characteristics of alkaline earth metal sulfonates useful as rust inhibitors are given in table 1 below.
Table- I
(Table Removed)

Accordingly the present invention provides an improved process for the preparation of alkaline earth metal alkyl ulfonates useful as temporary rust preventives which comprises sulfonation of heavy alkyl benzene fraction selected from boiling range 400 - 500°C with sulfuric acid concentration in the range of 90-105% and the amount of sulfuric acid being in the range from 1 to 5 times the weight of heavy alkyl benzenes fraction and temperature of sulfonation being maintained in the range of 10 - 150°C whereby water and sludge formed during said sulfonation and wherein the alkyl benzene sulfonic acid (sour oil) being separated from sulfonate acid mixture by settling at a temperature ranging 20 - 100°C for a period ranging 4-24 hours followed by neutralization with alkaline earth oxide/ hydroxide of mesh size of ab^af 200 and the said oxide/hydroxide used being in the form of slurry of the concentration ranging from 10-20% at a temperature ranging 30-80°C. to ph 7 to 8, separating the alkaline earth sulfonate from

neutralized mass by extraction with an aromatic solvent by conventional methods,
removing thesaid aromatic solvent by distillation to obtain neutral alkaline earth metal alkyl
aryl sulfonate which is over based by peptizing alkaline earth metal base and the ratio of
the said sulfonate and that of the alkaline earth metal base being kept in the range of 4:1

to 1:2 and by passing carbon dioxide in presence of C1to C10 aliphatic ketone and C1to C6 alcohols ^>
removing the solvents and redissolving contents in an aromatic solvent and centrifuging it to obtain a transparent solution from which solvent being removed to obtain basic alkaline earth metal alkyl aryl sulfonate .
In another embodiment of the present invention the temperature of sulfonation is maintained between 50 - 80°C.
In yet another embodiment of the present invention the neutralization of sour oil is carried out with alkaline earth oxide or hydroxide in a 10 to 50 percent slurry in temperature range 30-80°C
In still another embodiment of the present invention the neutralized sour oil is diluted with an aromatic solvent by 2 to 20 times of its volume and centrifuged at 2000 - 10,000 rpm for 0.25 to 10 hours to separate neutral alkaline earth alkyl aryl sulfonate solution from solid inorganic impurities.

The concentration of neutral alkaline earth sulfonate solution in hydrocarbon may be reduced to 20 to 60 percent by dilution with hydrocarbon oil before overbasing.
The neutral alkaline earth sulfonate may be treated with alkaline earth base such as oxide/ hydroxide such that sulfonate : calcium/ magnesium oxide/ hydroxide ratio is between 4:1 to 1:2.
The calcium/ magnesium oxide/ hydroxide used may have a particle size below 100 to 350 mesh preferably below 200 mesh and activated with a short chain alcohol from among methanol to butanol.
The mixture of neutral calcium magnesium sulfonate and activated calcium/ magnesium oxide/ hydroxide may be diluted with 1 to 4 times of its volume with aromatic solvent and an aliphatic ketone as promoter such that aromatic solvent to aliphatic ketone ratio is 20 : 1 to 1: 1.
The reaction mixture in the above claim may be reacted with carbon dioxide such that molar ratio of calcium/ magnesium oxide or hydroxide to carbondioxide varies between 1 : 1 to 4: 1.
The said moles of carbondioxide may be bubbled between 2 to 20 hours preferably between 3 to 8 hours at temperatures between 5 to 80°C.
The aromatic solvent, the aliphatic ketone and short chain alcohol may be removed by distillation while raising temperature between 100 - 150°C.

The remaining contents after distillation may be diluted with aromatic solvent by 2 to 15 times by weight and kept undisturbed for 1 to 8 hours.
The supernatant aromatic solvent may be centrifuged at 2000 - 8000 rpm for 0.25 to 5 hours.
The process of present invention is accomplished by sulfonation with sulfuric acid in a single shot to obtain alkyl aryl sulfonic acids in requisite concentration to obtain calcium and magnesium sulfonates of required concentration. Unlike other processes sulfonation with sulfurtrioxide and oleum is avoided such that no prior dilution is needed with an inert solvent.
In an embodiment of the process present invention involves preparation of basic calcium alkyl aryl sulfonates useful as rust inhibitors of out standing rust inhibiting quality from heavy alkyl benzenes such that no rust appears upto 300 hours when evaluated in 3 percent concentration in a mineral oil in a humidity cabinet by ASTM D-1748-83 rust test as compared to 72 hours with mineral oil alone and upto 200 hours with neutral calcium alkyl aryl sulfonates from the same source. These sulfonates act as excellent rust inhibitors in saline water conditions as well as in acidic and corrosive environment.
In the process of present invention heavy alkyl benzenes boiling range 230 - 458°C and 230 - 500°C respectively are subjected to fractional distillation under vacuum to remove lighter cuts boiling upto 400°C. The heavier fractions boiling between 410°C - 458°C and 418 - 500°C respectively are sulfonated with sulfuric acid (98 - 104%) with constant

stirring. The sulfonated oil is separated from the spent acid layer and neutralized with a 30 percent slurry of calcium hydroxide/ magnesium hydroxide till pH 9 to 10. The neutralized sulfonic acid is separated from rest of the inorganic impurities by dissolving in an aromatic hydrocarbon and centrifuging at 2000 - 5000 rpm for 0.25 to 5 hours. The aromatic hydrocarbon is distilled off and the calcium magnesium alkyl benzene sulfonate is dried under vacuum to remove the remaining solvent. Calcium/ magnesium sulfonate contains between 70 - 85 percent sulfonate and rest of it is unreacted hydrocarbon. Water content and inorganic salt falls between the measurable range. The base no. varies between 10 to 25 mg. KOH/g.
Neutral calcium/ magnesium sulfonate is diluted with mineral oil to bring down the concentration of sulfonate to a level of 40 - 60 percent. The sulfonate is diluted with toluene and an aliphatic ketone and treated with a 2.5 - 10 percent slurry of calcium oxide activated with anhydrous aliphatic alcohol. Carbon dioxide is bubbled such that it is 0.5 to 1.5 times the stiochiometric amount required to form metal carbonate over a period of 2 to 8 hours. The aliphatic alcohol, ketone and toluene is removed by distillation and the contents are heated upto 150°C cooled and diluted with an aromatic solvent. Supernatant liquid is centrifuged at 2000 - 5000 rpm for 0.25 to 5 hours. Aromatic solvent is removed from centrifbged solution by distillation.
The basic calcium/ magnesium sulfonate so obtained had nearly 2 to 4 times excess metal than the stiochiometric amount, remained transparent and stable for shelf life of more than six months. It had a base number between 80 - 150 mg KOH/g.

The rate of addition of sulfuric acid to heavy alkyl benzene and the speed of stirring should be between 5-50 g/min. and 900 ± 50 rpm respectively such that temperature of sulfonation is controlled between 50-80°C. The quantity of sulfuric acid : heavy alkyl benzene should between 1 to 3:1 by weight and concentration of sulfuric acid should not fall below 94% by weight. The particle size of calcium oxide/ hydroxide/ carbonate used in peptizing process for overbasing of the sulfonate should not be above 200 - 300 mesh and it must be activated with an alcohol boiling below 80°C. The temperature at which carbon dioxide is bubbled should be in the range 0 - 70°C and rate of bubbling should lie between 10.8 g/ hour to 30 gm/ hour per 1000 gm of sulfonate.
The following examples are given by way of illustration and should not be construed to limit the scope of the present invention :
Example 1:
1000 gm of heavy alkyl benzene fraction boiling between 410-480°C was taken in flask fitted with a stirrer and thermometer. 1500 gm of 98% sulfuric acid was added drop wise at the rate of 25 gm/ min. to heavy alkyl benzene with stirring at 1000 rpm. The temperature was raised to 60+5°C. The reaction continued for one hour. The contents were diluted with 1000 ml of water and 1000 ml of an aromatic solvent and neutralized with 500 gm of calcium oxide made into a slurry with 1000 ml of water to pH 9.5. 4 litres aromatic solvent was added and content heated to 80°C with stirring and allowed to settle for 10 minutes. The supernatant liquid was centrifuged at 1500 rpm for 3 hours. The centrifuged liquid was treated with 200 ml of an aliphatic ketone b.pt. 114°C. 220 gm of calcium oxide of particle size smaller than 100 mesh size activated with 800 ml of an

aliphatic alcohol boiling at 65°C. 60 litres of carbondioxide (pressure 2-3 atmospheres) is bubbled through the content for 2 hours. The temperature increased from 40 to 43°C. The aliphatic alcohol is recovered at 65 - 70°C and aromatic solvent and ketone above 80°C. The stirring continued for 2 hours at 140°C. The contents are diluted with 5 litres of aromatic solvent centrifuged at 3000 rpm for one hour. The solvent is distilled off to obtain a product of base no. 150 and percentage of calcium is 4.95.
Evaluation of the rust inhibiting properties in a 3% concentration in a 500 neutral mineral oil show that first rust spot appeared after 300 hours.
Example 2:
1000 gm. of heavy alkyl benzene fraction 420 - 500°C is taken in a flask fitted with a stirrer and thermometer. 800 gm. of 105% sulfuric acid (5% SOs) is added dropwise at the rate 15 gm./ min. to heavy alkyl benzene with stirring at 1000 rpm. The temperature is maintained at 45 + 5°C. The reaction continued for one hour after addition of all the sulfuric acid. The contents are diluted with 1000 ml. of an aromatic solvent and neutralised with 500 gm. of magnesium hydroxide made into slurry with 1.5 litres of water to pH 9.10 litres of aromatic solvent is added and contents are heated to 60°C with stirring and allowed to settle for 2 hours. The supernatant liquid is treated with 500 ml. of an aliphatic ketone b.pt. 78°C, 400 gm. of magnesium hydroxide of particle size smaller than 300 mesh activated with 1000 ml of an aliphatic alcohol boiling point 65°C. 40 litres of carbondioxide (pressure 5 atmospheres) is bubbled through the the contents over a period of 5 hours. The temperature is maintained at 25°C. The aliphatic alcohol, aromatic

solvent and ketone were recovered by distillation. The stirring is continued for two hours while the temperature is raised to 130°C. The contents are diluted with 5 litres of an aromatic solvent and centrifuged at 4000 rpm for 3 hours. The aromatic solvent is removed by distillation and the remaining solvent removed from overbase magnesium alkyi benzene sulfonate. The sulfonate content is 52%, magnesium percentage is 4.8 and base no. is 182. A 4 percent blend of this sulfonate in a 500 neutral mineral base oil showed appearance of first rust spot after 240 hours in the ASTM humidity cabinet rust test.
Example 3 :
1000 gm. of an heavy alkyl benzene fraction boiling between 420 - 500°C is sulfonated with 1000 gm. of the 100% sulfuric acid as per the conditions of sulfonation described in example 2. The contents of reaction are diluted with 1000 ml. of water and 1000 ml. of aromatic solvent boiling range 110 - 140°C and neutralized with 500 gm. of powdered lime passing through 200 mesh sieve to pH 9. 15 litres of aromatic solvent is added with stirring and allowed to settle for 6 hours. The supernatant liquid is centrifuged at 3000 rpm. for one hour. The centrifuged liquid is treated with 500 ml. of an aliphatic ketone boiling point 114°C. 400 gm. of calcium hydroxide of particle size smaller then 300 mesh is activated with 1000 ml. of an aliphatic alcohol boiling point 65°C. 40 litres of carbondioxide (pressure 2-3 atmospheres) is bubbled through the content over a period of 5 hours. The temperature is maintained at 20-25°C. The aliphatic alcohol, aromatic solvent and the ketone is removed by distillation while the temperature is raised to 125°C and maintained for one hour. The contents are diluted with 8 litres of aromatics solvent and centrifuged at 4000 rpm for one hour. The centrifuged liquid is distilled to remove

aromatic solvent to obtain calcium alkyl aryl sulfonate which is vacuum dried. The base number of the sulfonate is 250, the calcium content is 8.62 and the first rust spot appears after 280 hours when a 3 percent blend in 500 neutral mineral oil is evaluated by ASTM D 1748-83 rust test in humidity cabinet.
The main advantages of the process are :
1. Sulphuric acid 90 - 105% may be used instead of sulfur trioxide or oleum for
sulfonation and temperature of sulfonation may be between 50 - 80°C.
2. The sour oil separated from the spent acid may be neutralised with alkaline earth
oxide/ hydroxide/ hydroxide in a 10 to 50 percent slurry and the neutral alkaline
earth metal sulfonate may be recovered directly by solvent extraction and
centrifuging at 2000 - 10,000 rpm.
3. The neutral calcium sulfonate may be overabased with alkaline earth metal oxide
activated with an alcohol such that ratio sulfonate to alkaline earth metal oxide
may be 4:1 to 1:2.
4. The alkaline earth metal oxide/ hydroxide may have a particle size below 200 mesh
and may be peptised in presence of hydrocarbon oil, solvent and promoter such as
aliphatic ketone by passing carbondioxide between 3 to 8 hours at 5 to 80°C.
5. The solvent to may be recovered by distillation and a stable clear transparent
dispersion of alkaline earth metal base in sulfonate may be obtained.
6. The basic alkaline earth sulfonate obtain may be used as a rust preventive.

We Claim:
1. An improved process for the preparation of alkaline earth metal alkyl aryl
sulfonates useful as temporary rust preventives which comprises sulfonation of
heavy alkyl benzene fraction selected from boiling range 400 - 500°C with
sulfuric acid concentration in the range of 90-105% and the amount of sulfuric
acid being in the range from 1 to 5 times the weight of heavy alkyl benzenes
fraction and temperature of sulfonation being maintained in the range of 10 -
150°C whereby water and sludge formed during said sulfonation and wherein
the alkyl benzene sulfonic acid (sour oil) being separated from sulfonate acid
mixture by settling at a temperature ranging 20 - 100°C for a period ranging 4-
24 hours followed by neutralization with alkaline earth oxide/ hydroxide of
mesh size of about 0 200 and the said oxide/hydroxide used being in the form of
slurry of the concentration ranging from 10-20% at a temperature ranging 30-
80°C to pH 7 to 8, separating the alkaline earth sulfonate from neutralized mass
by extraction with an aromatic solvent selected from benzene , toluene by
conventional methods, removing the said aromatic solvent by distillation to obtain
neutral alkaline earth metal alkyl aryl sulfonate which is over based by peptizing
alkaline earth metal base and the ratio of the said sulfonate and that of the
(
alkaline earth metal base being kept in the range of 4:1 to 1:2 and by passing

carbon dioxide in presence of C1to C10aliphatic ketone and C1toC6 alcohol Removing
solvents and redissolving contents in an aromatic solvent such as herien described the range of claim and centnfuging it to obtain a transparent solution from which solvent being removed to obtain basic alkaline earth metal alkyl aryl sulfonate .
2. An improved process as claimed in claim 1, wherein the temperature of
sulfonation is maintained between 50 - 80°C.
3. An improved process as claimed in claim 1- 2, wherein the neutralization of
sour oil is carried out with alkaline earth oxide or hydroxide in a 10 to 50
percent slurry in the temperature range 30 -80°C.

4. An improved process as claimed in claim 1- 3 , wherein the neutralized sour oil

is diluted with an said aromatic solvent by 2 to 20 times of its volume and centrifuged at 2000 - 10,000 rpm for 0.25 to 10 hours to separate neutral alkaline earth alkyl aryl sulfonate solution from solid inorganic impurities.
5. An improved process as claimed in claim 1- 4, wherein the concentration of
neutral alkaline earth sulfonate solution in hydrocarbon is reduced to 20 to 60
percent by dilution with hydrocarbon oil before over basing.
6. An improved process as claimed in claims 1 to 5, wherein the neutral alkaline
earth sulfonate is treated with alkaline earth base such as oxide/ hydroxide such
that sulfonate: calcium/magnesium oxide/hydroxide ratio is between 4:1 to 1:2.
An improved process as claimed in claim 1- 6, wherein the calcium/ magnesium

oxide/ hydroxide used had a particle size below 350 the cope mesh preferably below
200 mesh and activated with a short chain, alcohol from among methanol to
butanol.
8. An improved process as claimed in claim 1- 7, wherein the mixture of neutral
calcium magnesium sulfonate and activated calcium/ magnesium oxide/
hydroxide is diluted with 1 to 4 times of its volume with aromatic solvent and an
aliphatic ketone as promoter such that aromatic solvent to aliphatic ketone ratio
is 20: 1 to 1:1.
9. An improved process as claimed in claim 1- 8, wherein the reaction mixture in
the above claims is reacted with carbon dioxide such that molar ratio of
calcium/magnesium oxide or hydroxide to carbon dioxide varies between 1:1 to
4:1.
10. An improved process as claimed in claim 1- 9, wherein the said moles of
carbon dioxide is bubbled between 2 to 20 hours preferably between 3 to 8
hours at temperatures between 5 to 80°C.

1 l.An improved process as claimed in claim 1-10 , wherein the aromatic solvent, the aliphatic ketone and; short chain alcohol is removed by distillation while raising temperature between 100 -150 C not
12. An improved process as claimed in claim 1-11, wherein the remaining contents
after distillation is diluted with aromatic solvent by 2 to 15 times by weight and
kept undisturbed for 1 8 hours.
13. An improved process as claimed in claim 1-12, wherein the supernatant
aromatic solvent is centrifuged at 2000 - 8000 rpm fro 0.25 to 5 hours.
14.An improved process for the preparation of alkaline earth metal alkyl aryl sulfonates useful as rust preventives substantially as herein described with reference to the examples.

Documents:

1307-del-1998-abstract.pdf

1307-del-1998-claims.pdf

1307-del-1998-correspondence-others.pdf

1307-del-1998-correspondence-po.pdf

1307-del-1998-description (complete).pdf

1307-del-1998-form-1.pdf

1307-del-1998-form-19.pdf

1307-del-1998-form-2.pdf

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Patent Number

215720

Indian Patent Application Number

1307/DEL/1998

PG Journal Number

12/2008

Publication Date

21-Mar-2008

Grant Date

03-Mar-2008

Date of Filing

15-May-1998

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG NEW DELHI-110 001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	ONKAR NATH ANAND	INDIAN INSTITUTE OF PETROLEUM , DEHRADUN-248005, INDIA.
2	ARUN KUMAR SINGH	INDIAN INSTITUTE OF PETROLEUM , DEHRADUN-248005, INDIA
3	KALYAN DUTT NEEMLA	INDIAN INSTITUTE OF PETROLEUM , DEHRADUN-248005, INDIA

PCT International Classification Number

C07C 03/44

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA