FORM 2
THE PATENT ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICA TION
(See section 10 and rule 13)
1. ' Title of the Invention
A PROCESS FOR OBTAINING HIGH PURITY ANACARDIC ACIDS FROM CASHEW NUT SHELL LIQUID
2. Applicant(s)
Name Nationality Address
TATA CHEMICALS INDIA BOMBAY HOUSE, 24 HOMI MODY
LIMITED STREET, MUMBAI - 400001
3. Preamble to the description
COMPLETE SPECIFICA TION
The following specification particularly describes the invention and the manner in which it is to
be performed.

The present disclosure relates to a process for obtaining anacardic acids from natural cashew nut shell liquid.
BACKGROUND
The Cashew nut shell liquid is a rich renewable by-products of the cashew industry. The nut has a shell of about 0.1 inch thickness inside which is a soft honeycomb structure containing a dark reddish brown viscous liquid. This liquid is called the cashew nut shell liquid, which is the pericarp fluid of the cashew nut. Cashew nut shell liquid is majorly a mixture of four components: all are substituted phenols - anacardic acid, cardanol, cardol and 2-methyl cardol. The ratio of different constituent varies with the raw material source and processing method.
Molecular structures of the main components of the Cashew nut shell liquid are as follows:



The side chains exist in saturated (n = 0), monoene (n = 1), diene (n = 2) and triene (n = 3) forms with the side chain double bonds in cis-configuration. The n is number of double bonds present in the side chain.
Off the various components of cashew nut shell liquid, anacardic acids are known to exhibit various biological activities while the other chief components, namely cardols and 2-methylcardols are considered toxic. This demands separation of biologically active anacardic acid from other components of cashew nut shell liquid. Various methods of separating anacardic acids have been tried such as column chromatographic technique and conversion of anacardic acids into calcium derivatives from which anacardic acids are recovered by breaking the complex/salt.
The conventional chromatographic separation of anacardic acids from other components of natural cashew nut shell liquid is by the use of silica gel column with a sample to stationary phase ratio of 1:20. This process, however effective, is not commercially viable since it

consumes very high amounts of solvents (usually hexane and ethyl acetate) and the process is time consuming (Kubo et al., 1986).
In order to make this process more efficient, medium scale chromatographic technique for separation of upto kilogram amounts of anacardic acid from other components of cashew nut shell liquid was developed by both stationary phase engineering and modifying the components of cashew nut shell liquid by selective derivatization (Indian patent application no. 298/MAS/1994 and Nagabhushana et.al. in J. Agric. Food Chem., 1995). In one method, selective derivatization of the anacardic acids to their alkyl ammonium salts that can get selectively retained on the silica column is carried out. Eluting the other un-retained non-acidic components of cashew nut shell liquid in the first phase is performed followed by eluting the acid by acidification of the eluting solvents. The major drawback of this process however, is the use of organic solvents for column purification. Moreover, the whole process is time consuming and recovery of solvents and the material is somewhat energy intensive.
Another method for obtaining anacardic acids from cashew nut shell liquid comprise of reacting the cashew nut shell liquid with lead hydroxide and/ or calcium oxide to form corresponding lead and/or calcium derivatives of anacardic acids, followed by washing away the alcohol soluble, unreacted cardanols, cardols and 2-methylcardols. Though the calcium derivatization method is cheaper, the semi-solid mass of calcium derivative of anacardic acids formed is not completely pure, it is always associated with impurity including highly undesirable cardols that needs to be further treated in order to bring about clear cut separation. The process is more complication when polymeric materials also form calcium derivatives and are difficult to separate from anacardic acid calcium derivatives. Further, treatment of anacardic acid metal salts with a mineral acid, in order to regenerate anacardic acids, leads to polymerization of the

enomers and therefore enables impure products. Finally, the calcium salt solution obtained by mineral acid treatment of the derivative is discarded at the end of the separation process, making it an environmental issue.
Thus there is a need for a process to obtain anacardic acids from cashew nut shell liquid in a simple and efficient manner. Further, the process should be such it produces only a minimal amount of waste products at the end.
SUMMARY
The disclosure relates to a process for obtaining anacardic acids from cashew nut shell liquid. The process includes preparing a solution of the cashew nut shell liquid in an alcohol, preparing an aqueous solution of a carboxylate salt of transition metal(II), reacting the solution of cashew nut shell liquid with the aqueous solution of carboxylate salt of transition metal(II) to obtain transition metal(II) derivative of anacardic acids. The process further includes reacting the transition metal(II) derivative of anacardic acids with acetic acid to regenerate anacardic acids; and separating the regenerated anacardic acids.
BRIEF DESCRIPTION OF DRAWINGS
The accompanying drawing illustrates the preferred embodiments and together with the following detailed description serves to explain the principles of the process.
Figure 1 illustrates HPLC chromatogram of anacardic acids produced through the proposed invention.
DETAILED DISCRIPTION
A process for obtaining anacardic acids from cashew nut shell liquid is disclosed.

In the present disclosure anancarid acids includes saturated anacardic acid, anacardic acid enes or their mixtures.
The process comprises of preparing a solution of the cashew nut shell liquid in an alcohol and preparing an aqueous solution of a carboxylate salt of transition metal(II). The solution of cashew nut shell liquid is reacted with the aqueous solution of carboxylate salt of transition metal(II) to obtain a transition metal(II) derivative of anacardic acids. The transition metal(II) derivative of anacardic acids is reacted with acetic acid to regenerate anacardic acids. The regenerated anacardic acids then seperated.
Any alcohol may be used to prepare the solution of cashew nut shell liquid including but not limited to methanol, ethanol, isopropanol or mixture thereof. The ratio of alcohol to cashew nut shell liquid is in the range of 3 0:1 to 1:1 and is preferably in the range of 24:1 to 15:1.
In accordance with an aspect, the carboxylate salt of transition metal II may be a carboxylate salt of any transition metal of periodic table having II oxidation state including but not limited to Copper, Nickel, Iron, Manganese, Cobalt or Chromium. In accordance with a preferred embodiment, carboxylate salt of transition metal II is copper(II) acetate.
The amount of the carboxlate salt of transition metal(II) used is in the range from 1.0 to 2.0 equivalent of anacardic acids present in the cashew nut shell liquid. In accordance with a preferred embodiment, the amount of the transition metal(II) salt is 1.25 equivalent of anacardic acid. The amount of the aqueous carboxylate salt of transition metal(II) solution used in the process ranges from 0.5 to 3 equivalents with respect to anacardic acids in the alcoholic solution of cashew nut shell liquid. The amount of anacardic acids present in the cashew nut shell liquid may be determined by any of the known process including but not limited to thin layer chromatography (both normal phase and reverse phase) using appropriate mobile phases having

acetic acid in trace amounts, checking the UV-Vis absorbance at 310 nm as against 280 nm for other phenolics and by HPLC using reversed phase column chromatographic technique having acetonitrile-water-acetic acid (80:20:1 v/v) mixture as mobile phase.
In accordance with an aspect, the solution of cashew nut shell liquid and the aqueous solution of the carboxylate salt of transition metal(II) are reacted to obtain a reaction mixture having a lipophilic organic mass (hereinafter called organic phase) and an aqueous methanolic phase (hereinafter called aqueous phase). The reaction mixture is held for a pre-determined period of time till the metal derivatives of anacardic acids are formed. The formation of transition metal(II) derivative of anacardic acids in the organic phase is indicated by change in colour of the phase.
In accordance with an aspect, the reaction mixture is stirred or vigorously shaken for a pre-determined period of time. The reaction mixture may be stirred or vigorously shaken for 15 minutes to 2.0 hours, and preferably the reaction mixture is stirred for 30 minutes. The reaction mixture is stirred or shaken at room temperature and at atmospheric pressure.
The organic phase is then separated from the aqueous phase. In accordance with an aspect, the organic phase may be separated from the aqueous phase by any known method including but not limited to decantation/phase separation or even filtration.
In accordance with an embodiment, the process further comprises of recovering solid transition metal(II) derivative of anacardic acid from the separated organic phase (In-case of saturated CNSL). Viscous (semi-solid) transition metal derivative of anacardic acids is obtained by first completely evaporating any solvent from the separated organic layer and then drying the

semi-solid thus obtained. The solid or viscous transition metal (II) derivative of anacardic acids may be washed with alcohol.
In accordance with an embodiment, the process further comprises of reacting the solid transition metal(II) derivative of anacardic acid, viscous transition metal(II) derivative of anacardic acid enes or both with acetic acid to obtain the soluble transition metal(II) acetate in solution and the insoluble organic mass, chiefly, anacardic acids. The insoluble anacardic acids and soluble transition metal(II) acetate may be separated by any of the known methods including but not limited to decantanation, centrifugation, filtration or their combination.
In accordance with an alternate embodiment, the solid or viscous transition metal (II) derivative of anacardic acids, may be dissolved in an organic solvent prior to reaction with acetic acid. In this embodiment soluble anacardic acids are retained in an organic layer while transition metal (II) acetate is formed and taken in to aqueous layer. The organic solvent may be any one of hexane, ethyl acetate, chloroform or xylene. The anacardic acids may be obtained from the organic layer by mere evaporation of the organic solvent.
The acetic acid used is glacial acetic acid. In accordance with an embodiment the amount of glacial acedic acid used is equivalent to the amount of anacardic acid present in the cashew nut shell liquid. In case glacial acetic acid is used, after breaking the complex/salt of transition(II) metal derivative of anacardic acids, water is added to take the soluble transition (II) metal acetate into aqueous layer and separate it from pure anacardic acids in organic layer. It is also possible to use moderately dilute acetic acid where by transition (II) metal acetate formed during shaking is taken into the aqueous layer. Alternately, the transition(II) metal derivative of

anacardic acid dissolved in an organic solvent is passed over a silica cartridge to get pure anacardic acids in an organic solvent.
In accordance with an aspect, the purity of the anacardic acid obtained by the process has the minimum purity of at least 92% and preferably 95%.
In accordance with an embodiment, the transition metal(II) derivative of cardanols, cardols and 2-methyl cardols formed in the reaction process are soluble in alcohol and therefore get separated from transition metal(II) derivative of anacardic acids that are relatively insoluble. The alcoholic solution of the transition metal(II) derivative of cardanols, cardols and 2-methyl cardols may also be utilized for various industrial process. Alternatively, a mixture of cardanols, cardols and 2-methyl cardols may also be obtained from the process by reacting the soluble transition metal(II) derivative of cardanols, cardols and 2-methyl cardols formed in the reaction process using acetic acid.
In accordance with an aspect, the cashew nut shell liquid is any cashew nut shell liquid that contains anacardic acids. Such cashew nut shell liquid may be cold extracted or natural cashew nut shell liquid, saturated cashew nut shell liquid or their mixture. Cold pressed or natural cashew nut shell liquid is obtained by cold pressing of shells obtained after the removal of edible kernel. This cold extracted or natural cashew nut shell liquid contains anacardic acids as the major component (upto 80%) along with cardols (15-20 %), 2-methyl cardols (2-3%) and a very small amount of cardanol (less than 2%) as the major phenolics.
Saturated cashew nut shell liquid is obtained by chemically hydrogenating natural cashew nut shell liquid using Pd/C or Pt/C catalyst such that all the enomers are converted to saturated analogues.

Example 1: Separation of anacardic acids from cashew nut shell liquid
25 g of cashew nut shell liquid was admixed with 600 ml of methanol in a 1000 ml conical flask, and the resulting solution was allowed to stir for 30 minutes to get a homogeneous solution. The resultant solution thus obtained, depending on the percentage of anacardic acids present 0.7 equivalent of copper anacardate dissolved in water (100 ml) was added and the resulting biphasic mass stirred for about 30 min at room temperature. The organic layer was separated from the aqueous layer by mere decantation. The organic layer, which is green colored mass, insoluble in aqueous but soluble in organic solvents was taken in hexane (200 ml) dried over anhydrous sodium sulphate and was stirred with an aqueous solution of glacial acetic acid in water (10 ml in 50 ml water). The organic layer was separated, solvent evaporated to get anacardic acid enes.
If the stirring with copper acetate is extended to more than 12 hours, using higher concentration of copper acetate (more than 1.5 equivalent) an yellow colored 1:1 derivative of anacardic acid copper(II) forms that is being insoluble in aqueous solution.
Example 2: Separation of anacardic acid from saturated cashew nut shell liquid
Natural CNSL was hydrogenated using 10 % Pd/C catalyst to generate saturated CNSL. 25 g of saturated cashew nut shell liquid was dissolved in 600 ml of methanol in a 1000 ml conical flask, and the resulting solution was allowed to stir for 30 minutes to get a homogeneous solution. The resultant solution thus obtained, depending on the percentage of anacardic acid present, 0.7 equivalent of copper anacardate dissolved in water (100 ml) was added and the resulting biphasic mass stirred for 30 min. at room temperature. The solid organic layer was separated from the aqueous layer by decantation. The solid layer, which is green colored mass, insoluble in aqueous but soluble in organic solvents was taken in an organic solvent (ethyl acetate; 400 ml) dried over

anhydrous sodium sulphate and solvent evaporated to get the copper derivative. If the stirring of CNSL with copper acetate is extended for more than 12 hours using higher concentration of copper acetate (more than 1.5 equivalent), an yellow colored precipitate of a 1:1 derivative of anacardic acid copper forms that is being insoluble in aqueous solution. The green anacardic acid copper derivative was re-suspended in an organic solvent (100 ml: hexane, ethyl acetate, chloroform, xylene etc.,) and was stirred with an aqueous solution of glacial acetic acid where by anacardic acid was regenerated in the organic phase. The anacardic acid was recovered by solvent evaporation.
Example 3: HPLC analysis of the anacardic acids
The anacardic acids obtained through the process was analyzed the using HPLC (C18 column; 4.6 mm X 250 mm of Agilant). The HPLC analysis value has been shown in below table 1 and chromatogram of the analysis has been represented in the fig. 1.
Table 1:

Serial Number Name Retention Time Area % Area Height
1 Unidentified 2.824 38899 0.2 7719
2 Unidentified 4.713 77090 0.4 3711
3 Anacardic acid-triene 11.074 7151144 36.85 339490
4 Unidentified 14.121 174615 0.9 9839
5 Anacardic acid-diene 16.676 3330121 17.16 127018
6 Unidentified 18.345 183451 0.95 7808

7 Unidentified 20.794 119501 0.62 5482
8 Unidentified 25.275 140342 0.72 4777
9 Anacardic acid-monoene 27.292 7414633 38.21 139887
10 Unidentified 36.493 242287 1.25 5801
11 Anacardic acid-saturated 53.924 533161 2.75 8219
The above data clearly shows that the purity of anacardic acid obtained through the process has the purity of 94.97%.
INDUSTRIAL APPLICABILITY
The process as described above allows for obtaining anacardic acids in a simple and efficient manner at high purity. The anacardic acids thus obtained may be used for any of the recently known technological applications or their biological functions. Moreover, the metal derivative or other components of the cashew nut shell liquid, namely, cardanols, cardols and 2-methyl cardols can be used for biopesticide applications.
When introducing elements of the examples disclosed herein, the articles "a," "an," "the" and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including" and "having" are intended to be open-ended and mean that there may be additional elements other than the listed elements. It will be recognized by the person of ordinary skill in the art, given the benefit of this disclosure, that various components of the examples can be interchanged or substituted with various components in other examples.

Although certain aspects, examples and embodiments have been described above, it will be recognized by the person of ordinary skill in the art, given the benefit of this disclosure, that additions, substitutions, modifications, and alterations of the disclosed illustrative aspects, examples and embodiments are possible.

We claim
1. A process for obtaining anacardic acids from cashew nut shell liquid comprising:
- preparing a solution of the cashew nut shell liquid in an alcohol;
- preparing an aqueous solution of a carboxylate salt of transition metal(II);
- reacting the solution of cashew nut shell liquid with the aqueous solution of carboxylate salt of transition metal(II) to obtain transition metal(II) derivative of anacardic acids;
- reacting the transition metal(II) derivative of anacardic acids with acetic acid to regenerate anacardic acids; and
- separating the regenerated anacardic acids.

2. The process as claimed as claim 1, wherein the amount of acetic acid is atleast 2 equivalent to the amount of anacardic acids present in the cashew nut shell liquid.
3. The process as claimed in claim 1, wherein the alcohol is methanol, ethanol, propanol, isopropanol, a higher alcohol or a mixture thereof.
4. The process as claimed in claim 1, wherein the ratio of alcohol to cashew nut shell liquid ranges from 30:1 to 1:1.
5. The process as claimed in claim 1, wherein the carboxylate salt of transition metal(II) is a carboxylate salt of any one of Cobalt, Nickel, Iron, Magnesium, Copper, Chromium.

6. The process as claimed in claim 1, wherein the carboxylate salt of transition metal(II) is a copper acetate.
7. The process as claimed in claim 1, wherein the amount of carboxylate salt of transition metal(II) is in the range of 0.5 to 2.0 equivalents of the amount of the anacardic acids present in cashew nut shell liquid.
8. A process as claimed in claim 1, further comprising of dissolving the transition metal(II) derivative of anacardic acids in an organic solvent prior to reacting with acetic acid.
9. A process as claimed in claim 7, wherein the organic solvent is any one of hexane, ethyl acetate; chloroform or xylene.