FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Biodegradable, non-carcinogenic, vegetable oil pour point depressants and processes for the preparation thereof
APPLICANTS
Crompton Greaves Limited, CG. House, 6th House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company.
INVENTORS
Chaudhari Sushil Ekanath of Crompton Greaves Limited, CG House, 6 House, Dr Annie Besant Road, Prabhadevi, Mumbai 400 030, Maharashtra, India, an Indian National.
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
This invention relates to biodegradable, non-carcinogenic, vegetable oil pour point depressants, dialkyl ester of poiy-(alkyl oleate-co-maleic anhydride) of formula (I):

CH-

"CH-

CW

CH-

(CHj),

C=0 C=0

CH.

OR

OR

OR

11

wherein R represents Cio to C22 straight chain aliphatic aikyi group; and n represents the number of repeating units
and processes for the preparation thereof
BACKGROUND OF THE INVENTION
Unfortunately, oils, hydraulic fluids, and other petroleum-based products have tendency to inevitably leak onto ground surfaces, eventually resulting in contamination of the environment. Much effort has been directed to avoiding such contamination. One promising approach has been to replace the base fluid typically, a petroleum-derived hydrocarbon with a vegetable oil, such as a naturally occurring or synthetic triglyceride or ester thereof Vegetable oils are biodegradable, and thus environmentally friendly.

Unfortunately, triglycerides have poor low temperature viscometrics, and tend to congeal at temperatures below about -10° C. Many industrial fluids must have a pour point of less than -25° C and a Brookfield viscosity of 7500 to 110,000 centiPoise (cP) at -25° C. In order for triglycerides to be used successfully as industrial base fluids, their low temperature viscometry must be improved.
The paraffin/wax of the vegetable oil also starts to crystallize in the form of thin plates, needles or mal-crystals in cold condition. At low temperatures, the plate shaped wax crystals coil on their edges forming needle shaped wax crystals which compact into a 3-dimensional network to form cage like structures. Thus, in cold conditions, when the paraffm from the oil begins to precipitate out, it increases the viscosity of oil, and causes operational problems in the transformers. Energization of the transformer in cold conditions is also a problem. The storage of oil is also adversely affected in cold conditions due to the wax crystal fonnation.
In their natural state, vegetable oils have high viscosity which causes operational problems in transformers. Hence, all vegetable oils are transesterified prior to use as insulating fluids which also increases the cost.
In transformers the oil provides two major functions; the first is as an insulator and the second is as a heat transfer medium to carry heat from the coils to the cooling surfaces of the transformer. These oils must be low in corrosive agents such as acid, alkali and sulfur and resistant to oxidation and sludge formation. In addition to possessing relatively low viscosity, high

electric strength and a relatively high flash point, these oils are further characterized in that they must have a relatively low pour point. This is particularly necessary when the oils are used in transformers in colder climates.
A number of compounds are known to improve the low temperature viscometrics of vegetable oils. These compounds are known as "pour point depressants"(PPD's). Pour point depressants are designed to control wax crystal formation in crude oil resulting in improved flow performance of the vegetable oil at lower temperatures, i.e, the PPDs lower the pour point of the vegetable oil. Pour point depressants, when added to the crude oil, hinder the crystallization of the wax molecules by incorporation of the PPD molecules on the fastest growing edge of the wax crystals thereby forming an imperfection on the crystal face and sterically hindering further growth in that direction and thus preventing wax crystallization and deposition. This reduces the pour point of the oil.
Known PPD's for triglycerides include, but are not limited to: modified carboxy containing interpolymers; acrylate polymers; nitrogen containing acrylate polymers; and, methylene linked aromatic compounds. Unfortunately, known PPDs are not biodegradable. Therefore, the advantage in low temperature viscometry that is gained by using these PPD's is largely offset by the decrease in biodegradability of the resulting product. Also, manufacturing and environmental specifications limit the total amount of non-biodegradable material that can be used in a particular industrial fluid.

Many of these pour point depressants like polymethacrylates, polyacrylates and polyalkyl methacrylates are known to be expensive and even carcinogenic,
Biodegradable and non-carcinogenic PPDs, which would meet the applicable specifications and not compromise the overall biodegradabihty of industrial fluids, are sorely needed.
OBJECTS OF THE INVENTION
An object of the invention is to provide a bio-degradable, non-carcinogenic pour point depressant for vegetabl oil.
Another object of the invention is to provide a bio-degradable, non-carcinogenic pour point depressant for vegetable oil which is economical.
Another object of the invention is to provide a process for the preparation of a bio-degradable, non-carcinogenic pour point depressant for vegetable oil.
Another object of the invention is to provide a process for the preparation of a bio-degradable, non-carcinogenic pour point depressant for vegetable oil which is simple, easy and convenient to carry out and is economical.

DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided dialkyl ester of poly-(aIkyl oleate-co-maleic anhydride) copolymer having general formula (I) :

CH -CH Clt^
I OR

CH-

OR

OR

n

Formula (I)
wherein R represents C10 to C22 straight chain aliphatic alkyl group; and n represents the number of repeating units.
having pour point depressant activity in vegetable oil.
Particularly, dialkyl ester of poly-(alkyl oleate-co-maleic anhydride) copolymer of formula (I) are as follows :
1. Poly-(dodecyl oleate -co-maleic anhydride)didodecylate of the formula (II);

CH <:H cit

CH

C-O CH3

Formula (II) wherein n represents the number of repeating units 2. PoIy-(decyl oleate -co-maleic anhydride)didecylate of the formula
(HI);

CH <:H CHr

CH-

(CH,).
27
(CH,), 0=0 C^
OC10H21 OC10H21
C=0 CH3
I

n

Formula (III) wherein n represents the number of repeating units
3. Poly-(hexadecyl oleate-co-maleic anhydride)dihexadecylate of the formula (IV);
CH -CH—-CH CH-

(9^2)7
(CH^, C=0 C=0
OC16H33 OCj^l^3
C=0 CH3

n

formula (IV)
wherein n represents the number of repeating units
4. Poly-(tetradecyl oleate-co-maleic anhydride)ditetradecylate of the formula (V);

CH <:H CH CH

(CHj),
(CH2)7
C-O ^^3

OC14H29 OC14H29

II
Formula (V)
wherein n represents the number of repeating units
5. Poly-(Octadecyl oleate-co-maleic anhydnde)dioctadecylate of the formula (VI);
-CH -CH CH CH

(9*^2)7
(CH,), fO f=0
OCj^Hjc, OC14H29
C=O CH3

II
Formula (VI)
vvherein n represents the number of repeating units and
6. Poly-(behenyl oleate-co-maleic anhydride)dibehenate of the formula
(VII).

CH CH CH CH-

(9^2)7

(9"2)7
CH,

OC22H45 OC32H45

OC22H45

II

Formula (VII) wherein n represents the number of repeating units
According to the invention there is also provided process for the preparation of dialkyl ester of poly-(alkyl oleate-co-maleic anhydride) copolymer having formula (I) :

CH -CH
-CH CH-
I I I
I OR OR
CH3
OR

n

Formula (I)
wherein R represents C10 to C22 straight chain aliphatic alkyl group; and n represents the number of repeating units.
having pour point depressant activity in vegetable oil, the process comprising:
a) esterifying oleic acid with C10 to C22 aliphatic alcohol in the molar ratio of 2:1 in the presence of an organic solvent and

sulphuric acid catalyst at 110oC to 140oC under azeotropic conditions to obtain an alkyl ester of unsaturated fatty acid;
b) co-polymerizing the alkyl ester of oleic acid with a double re-crystallized maleic anhydride in the 1:1 molar ratio under inert atmosphere and in the presence an organic solvent and a free radical initiator at SO'^C to 75"C to obtain a poly(alkyl ester of oleic acid -co-maleic anhydride) copolymer; and
c) diesterifying the copolymer with C]o to C22 aliphatic alcohol in the molar ratio of 1:2 at 110oC to 140° C in the presence of an organic solvent and an acid catalyst.
Preferably, C10 to C22 aliphatic alcohol is selected from behenyl alcohol, decyl alcohol, dodecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, octadecyl alcohol, etc.
Preferably, the solvent is selected from toluene, dry benzene or xylene or toluene. Preferably, the inert atmosphere is provided by dry nitrogen gas. Preferably, the free radical initiator is benzoyl peroxide or azobisisobutyronitrile (AIBN). Preferably, the acid catalyst is para-toluene sulfonic acid or sulphuric acid or combination thereof.
The molecular weight of the above-mentioned co-polymer is in the range of 20,000 to 50,000.

Oil used is non-edible oil such as vegetable oil, crude oil or a combination of vegetable oil and crude oil. Preferably, oil used is vegetable oil. More preferably, vegetable oil used is rapeseed oil.
The invention also provides a vegetable oil comprising dialkyl ester of poly-(alkyl oleate-co-maleic anhydride) copolymer having formula (I) :

-CH CH CH CH-
III
(CH,)- (CH2)7
OR OR
OR

n

Formula (I)
wherein R represents C10 to C22 straight chain aliphatic alkyl group; and n represents the number of repeating units.
having pour point depressant activity in vegetable oil.
The oil comprises 100 to 500 ppm of dialkyl ester of poly-(alkyl oleate-co-maleic anhydride) copolymer to improve the pour point of oil.
The dialkyl ester of poly-(alkyl oleate-co-maleic anhydride) copolymer of
the invention is very effective and efficient in improving the pour point of
vegetable oil and is prepared using raw materials like behenyl alcohol, decyl
alcohol, dodecyl alcohol and oleic acid which are easily obtainable from the
naturally occurring fats and oils. These pour point depressants are easily
biodegradable and non-carcinogenic. Therefore, the pour point depressant of

the invention is non-carcinogenic, economical and bio-degradable. The process of the invention is also simple, easy and convenient to carry out and economical.
The following experimental examples are illustrative of the invention but not limitative of the scope thereof:
Example 1
Oleic acid (0.08 M, 22.59 g) was etherified with octadecyl alcohol (0.04 M, 10.81 g) at 111°C for 12 hours in the presence of toluene (70 ml) and sulphuric acid (0.2 ml) to obtain octadecyl oleate. Water was eliminated from the reaction mixture by azeotropic distillation. The resulting crude ester was neutralized with sodium bicarbonate. The organic layer was separated and washed with water to remove traces of sodium bicarbonate and finally dried over anhydrous sodium sulphate. Solvent recovery was achieved by vacuum distillation.
The octadecyl oleate (0.02 M, 10.699 g) was copolymerized with double re-crystallized maleic anhydride (0.02 M, 1.96 g) in the presence of dry benzene under dry nitrogen atmosphere with azobisisobutyronitrile at 55 to 60°C with constant stirring for 5 hours to give poly(behenyl oleate-co-maleic anhydride) which was purified by repeated solvent non-solvent precipitation (benzene-methanol) method. Traces of the solvent were removed by drying under reduced pressure at 50oC / 25mm Hg for 5 hours.

The poly(octadecyl oleate-co-maleic anhydride) (0.02 M, 12.66 gm) was diesterified with 2 moles of octadecyl alcohol (0.04 M, 10.81 gm) in the presence of xylene (70 ml) and para-toluene sulfonic acid (0.1 gm) and sulphuric acid (0.1 ml) at 140°C to produce poly(0ctadecyl oleate-co-maleic anhydride)dioctadecyiate which was neutralized with sodium bicarbonate and separated and dried over anhydrous sodium sulfate. Solvent was recovered by vacuum distillation. The crude diester was purified by repeated precipitation in excess acetone and dried under vacuum at 40°C/25mm Hg for 5 hours. The poly(octadecyl oleate-co-maleic anhydride)dioctadecylate obtained in this example had a molecular weight up to 50,000.
Example 2
Oleic acid (0.08 M, 22.59 g) was esterified with behenyl alcohol (0.04 M, 13.064 g) at 111°C for 12 hours in the presence of toluene (75 ml) and sulphuric acid (0.2 ml) to obtain behenyl oleate. Water was eliminated from the reaction mixture by azeotropic distillation. The resulting crude ester was neutralized with sodium bicarbonate. The organic layer was separated and washed with water to remove traces of sodium bicarbonate and finally dried over anhydrous sodium sulphate. Solvent recovery was achieved by vacuum distillation.
The behenyl oleate (0.02 M, 11.82 g) was copolymerized with double re-crystallized maleic anhydride (0.02 M, 1.96 g) in the presence of dry benzene under dry nitrogen atmosphere with azobisisobutyronitrile at 55 to 60°C with constant stirring for 5 hours to give poly(octadecyl oleate-co-maleic anhydride) which was purified by repeated solvent non-solvent

precipitation (benzene-methanol) method. Traces of the solvent were removed by drying under reduced pressure at 50°C / 25mm Hg for 5 hours.
The poly(behenyl oleate-co-maleic anhydride) (0.015 M, 10.33 gm) was diesterified with 2 moles of bewhenyl alcohol (0.03 M, 9.79 gm) in the presence of xylene (80 ml) and para-toluene sulfonic acid (O.I gm) and sulphuric acid (0.1 ml) at 140°C to produce poly(behenyl oleate-co-maleic anhydride)dibehenate which was neutralized with sodium bicarbonate and separated and dried over anhydrous sodium sulfate. Solvent was recovered by vacuum distillation. The crude diester was purified by repeated precipitation in excess acetone and dried under vacuum at 40"C/25mm Hg for 5 hours. The poly(behenyl oleate-co-maleic anhydride)dibehenate obtained in this example had a molecular weight up to 50,000.
Example 3
100 ppm and 500 ppm of poly(behenyl oleate-co-maleic
anhydride)dibehenate prepared according to Example 1 and poly(octadecyl oleate-co-maleic anhydride)dioctadecylate prepared according to Example 2 were added to rapeseed oil and tested for its pour point depressant activity. The pour point depressant additives of the invention were tested for its pour point depressant activity by standard method as prescribed by the ASTM D97. The results of the pour point of the rapeseed oil on addition of varying amounts of poly(behenyl oleate-co-maleic anhydride)dibehenate and

poIy(octadecyl oleate-co-maleic anhydride)di octadecylate were shown in the Table 1.
Table 1 : Pour point depressant of rapeseed oil after adding varying amount of poly(behenyl oleate-co-maleic anhydride)dibehenate and poly(octadecyl oleate-co-maleic anhydride)di octadecylate in the rapeseed oil.

Pour point of virgin rapeseed oil - 12 °C
Pour point of rapeseed oil after addition of 100 ppm Poly(beheny] undecyJenate-co-ma]eic anhydride) dibehenate - 18 °C
Extent of depression in pour point after addition of 100 ppm Poly(behenyl undecylenate-co-maleic anhydride) dibehenate 6°C
Pour point of rapeseed oil after addition of 500 ppm Poly(behenyl undecylenate-co-maleic anhydride) dibehenate -21°C

Extent of-depression in pour point after addition of 500 ppm Poly(behenyl undecylenate-co-maleic anhydride) dibehenate 9°C
Pour point of rapeseed oil after addition of 100 ppm poly(octadecyl oleate-co-maleic anhydride)di octadecylate - 18 °C
Extent of depression in pour point after addition of 100 ppm poly(octadecyl oleate-co-maleic anhydride)di octadecylate 6°C
Pour point of rapeseed oil after addition of 500 ppm poly(octadecyl oleate-co-maleic anhydride)di octadecylate -24°C
Extent of depression in pour point after addition of 500 ppm poly(octadecyI oleate-co-maleic anhydride)di octadecylate 12 X
Above table clearly shows that the pour point depressant of the invention comprising poly(octadecyl oleate-co-maleic anhydride) and poly(behenyl oleate-co-maleic anhydride) has excellent pour point depressant activity in

rapeseed oil in a range of concentrations from 100ppm and 500ppm. The pour point of the rapeseed oil was reduced up to - 24°C.

We claim :
1. Dialkyl ester of poly-(alkyl oleate-co-maleic anhydride) copolymer having general formula (I) :

CH -CH~
(CH2),
CH.

I OR

CH-
I
OR

OR

11

Formula (I)
wherein R represents C10 to C22 straight chain aliphatic alkyl group; and n represents the number of repeating units.
having pour point depressant activity in vegetable oil.
2. Poly-(dodecyl oleate -co-maleic anhydride)didodecylate of the formula (II);

CH
CH -CH CH
(CH,),
(CH,), C=O C=O
CH.
oc12H25 OC12H25

Formula (II)
wherein n represents the number of repeating units
having pour point depressant activity in vegetable oil.

II

3. Poly-(decyl oleate -co-maleic anhydride)didecy!ate of the formula (HI);
CH -CH CH CH-

(CH2)7
(CH2)7

OC10H21 OC10H21

II

Formula (III)
wherein n represents the number of repeating units
having pour point depressant activity in vegetable oil.
4. Poly-(hexadecyl oleate-co-maleic anhydride)dihexadecylate of the formula (IV);
CH -CH CH CH-
(CH2)7

I OC16H33
C=0 CH3

OC16K33 OC16H33

n

Formula (IV) wherein n represents the number of repeating units
having pour point depressant activity in vegetable oil.

5. Poly-(tetradecyl oleate-co-maleic anhydride)ditetradecylate of the formula (V);

CH -CH CH

CH

(CH,),
(CH,), C=O fO
27
OCl4H29 OC14H29
C=0 *^^3

n

Formula (V) wherein n represents the number of repeating units
having pour point depressant activity in vegetable oil.
6. Poly-(Octadecyl oleate-co-maleic anhydride)dioctadecylate of the formula (VI);

-CH-
CH-
(CH2)7 C=O

-CH ca-
(CH,), C=O
CH.
OC14H29 OC14H29

Formula (VI).
wherein n represents the number of repeating units
having pour point depressant activity in vegetable oil.

7. Poly-(behenyl oleate-co-maleic anhydride)dibehenate of the formula (VII).
CH CH CH CH

(CHj), 0=0
(CH,), C=O C=O
OC23H45 OC22H45
C=O CH3

11

Formula (VII) wherein n represents the number of repeating units
having pour point depressant activity in vegetable oil.
8. A process for the preparation of dialkyl ester of poly-(alkyl oleate-co-maleic anhydride) copolymer having formula (I) :

(CH,), OR
CH -CH CH CH-
(CH2)7,
OR OR
CH,

II

Formula 1
wherein R represents C10 to C22 straight chain aliphatic alkyl group; and n represents the number of repeating units.
having pour point depressant activity in vegetable oil, the process comprising:

a) esterifying oleic acid with C10 to C22 aliphatic alcohol in the molar ratio of 2:1 in the presence of an organic solvent and sulphuric acid catalyst at 110°C to 140oC under azeotropic conditions to obtain an alkyl ester of unsaturated fatty acid;
b) co-polymerizing the alkyl ester of oleic acid with a double re-crystallized maleic anhydride in the 1:1 molar ratio under inert atmosphere and in the presence an organic solvent and a free radical initiator like benzoyl peroxide or azobisisobutyronitrile (AIBN) at 50oC to 75oC to obtain a poly(alkyl ester of oleic acid -co-maleic anhydride) copolymer; and
c) diesterifying the copolymer with C10 to C22 aliphatic alcohol in the molar ratio of 1:2 at 110° C to 140° C in the presence of an organic solvent and an acid catalyst like para-toluene sulfonic acid or sulphuric acid or combination thereof

9. The process as claimed in claim 8, wherein C10 to C22 aliphatic alcohol used is selected from behenyl alcohol, decyl alcohol, dodecyl alcohol, tetradecyl alcohol, hexadecyl alcohol, octadecyl alcohol, etc.
10. The process as claimed in claim 8, wherein the solvent is selected from toluene, dry benzene or xylene or toluene.
11. A vegetable oil comprising dialkyl ester of poly-(alkyl oleate-co-maleic anhydride) copolymer having formula (I) :

CH CH CH CH

(CH2)
(CH,), C=O C=O
OR OR
C=0 CH3
OR

II

Formula (I)
wherein R represents C10 to C22 straight chain aliphatic alkyl group; and n represents the number of repeating units.
having pour point depressant activity in vegetable oil.