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, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Energy efficient process for synthesis of aliphatic amino acid salts
APPLICANTS
Reliance Industries Limited, 3rd Floor, Maker Chamber IV, 222, Nariman Point, Mumbai 400021, Maharashtra, India, an Indian company
INVENTORS
Patil Harshad Ramdas, A-103, Laxmidarshan Apartment, Nr. Merulaxmi Temple, Rander Road, Tadwadi, Surat - 395 009, Gujarat, India, Bhajiwala Hiren Manojkumar, B-21, Pushpam Raw House, B/H Rajhans Cinema, Surat-Dumas Road, Piplod, Surat-395 007, Gujarat, India and Gupta Virendrakumar, Apartment-703, Maitri Tower, Sector -29, Nerul (East), Navi Mumbai -400706, Maharastra, India, all Indian nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes this invention and the manner in which it is to be performed:

Field of Invention
This invention relates to an energy efficient process for the synthesis of aliphatic amino acid salts. More particularly, the invention relates to an energy efficient and economical process for the synthesis of aliphatic amino acid salts by hydrolysis of lactams.
Background of the invention
The hydrolysis of lactams to give the corresponding aliphatic amino acids is a well documented process.
US2453234 discloses that the hydrolysis of lactams with strong acid results in the formation of salt combinations with the amino group of the amino carboxylic acids from which it is extremely difficult to recover the free amino carboxylic acids in pure form.
US3113966 discloses a process for hydrolyzing caprolactams comprising refluxing of caprolactam, sulfuric acid and water, wherein the refluxing temperature can go upto 150 - 155
°C.
US 5391780 discloses a process for preparing amido-carboxylic acids in water comprising hydrolyzing a lactam at a temperature of 150 - 300 °C. to form a mixture containing an amino acid; cooling to a temperature of 25 - 100 °C: reacting a carboxylic acid anhydride with the above formed amino acid formed to form a reaction mixture containing an organic layer which contains an amido-carboxylic acid and an aqueous layer and separating the amido-carboxylic acid containing organic layer from the aqueous layer. The patent specifically discloses that the reaction of hydrolyzing a lactam may be carried out over a wide range of temperatures, but at temperatures below 150 °C. the reaction rate of hydrolysis of the lactam monomer is very slow. On the other hand, it is generally not desirable to exceed temperatures above 300 °C inasmuch as polymerization of the lactam may take place. In addition, at such high temperatures, a higher operating pressure would be needed to contain the water. Accordingly, a temperature between 150 - 300 °C is satisfactory. Temperatures of 200 - 250 °C are particularly desirable in the substantial absence of oxygen. The time of the reaction is generally 2 to 10 hours, preferably 4 to 8 hours.

US6986839 discloses a process for the preparation of six amino hexanoic acid from caprolactum. The process involves agitating and heating a mixture of caprolactam, sodium hydroxide and water to a temperature of 105 - 120°C for six hours. The conversion of caprolactam to six amino hexanoic acid was found to be >75%.
Many other similar processes for the hydrolysis of lactams have also been disclosed, however all these processes require temperature in excess of 105°C. At higher scale of production, the synthesis of such products are not suitable in stainless or mild steel reactors mainly due to the chances of stress corrosion cracking at temperatures above 105°C under alkaline conditions. Stress corrosion cracking can lead to catastrophe failure of reactor causing serious process hazards. The only option available is to use reactors made of iron, nickel or chromium which is very costly compared to stainless steel reactors.
In contrast, the present inventors have unexpectedly discovered a process for synthesis of aliphatic amino acid salts from lactams at a temperature which is much below 105°C. Furthermore, the present inventors have also discovered that the process provides the aliphatic amino acid salts in very high conversion rates.
Summary of the invention
The present invention relates to a process for the synthesis of aliphatic amino acid salts comprising hydrolyzing lactam in an aqueous media in the presence of alkali, wherein the temperature is in the range of 85 - 90°C, the reaction time is 3 - 6 hours and the molar ratio of the alkali : lactam is 1.2:1 - 1.3:1.
Brief description of the drawing
Fig. 1 illustrates a graph depicting the stress corrosion cracking of stainless steel under sodium hydroxide media as function of temperature.
Detailed description of the invention
The present invention relates to a process for the synthesis of aliphatic amino acid salts comprising hydrolyzing lactam in an aqueous media in the presence of alkali, wherein the

temperature is in the range of 85 - 90°C, the reaction time is 3 - 6 hours and the molar ratio of the alkali : lactam is 1.2:1 - 1.3:1.
In an embodiment, the present invention is preferably carried out at a temperature of 85°C.
In an embodiment the mofar ratio of the alkali : lactam is preferably 1.2:1.
In an embodiment, the lactam is selected from the group consisting of butyrolactam, valerolactam, epsilon-caprolactam, beta-propiolactam, delta-valerolactam, and similar lactams.
In another embodiment, the alkali is selected from sodium hydroxide or potassium hydroxide.
In yet another embodiment, the aqueous media is water, preferably distilled water or alcohol.
The lowering of the temperature to 85-90°C avoids the high temperature stress cracking of steel, thereby enabling the use of normal stainless steel reactor instead of the costly material of construction (Figure 1; Sourced from: Copsorn 1963: INCO Databooks 1973 ; Swanby Chemical Engineer, Vol.69, Nov 1972). The figure indicates stress-corrosion cracking phenomena with respect to temperature in basic media for stainless steel. The operating temperature below 210 °F or 99 °C is considered as safe limit for operation to avoid corrosion. The operating temperature above this limit generally leads to loss of material due to stress corrosion and will lead to failure of reactor. Therefore, lowering the temperature avoids the pressure build up that is inevitable when the solvent is water and the reaction temperature is equal to or higher than 100°C. Moreover, the lower reaction temperature and the lower reaction time with higher conversion rates is much more energy efficient and economical as compared to prior art processes.
The reaction conditions, as claimed by the present inventors, give very high conversion of caprolactams, i.e. the conversion rates are 99.5 - 99.8%.
The process of the present invention will be further illustrated by a consideration of the following example, which are intended to be exemplary of the invention.

Examples
Caprolactam (9g, 0.0796 mol), sodium hydroxide (3.5g, 0.0955 mol) and 12.5 g water was added into a two-necked round bottom flask equipped with condenser along with magnetic bar for stirring at 700 count (molar ratio of NaOH/caprolactam = 1.2). The mixture was agitated and heated in an oil bath at 85°C for 6 hrs. The samples were taken at 3 and 6hrs for the conversion study by proton NMR. The conversion and product formation study was carried out on proton NMR.
The result showed that a conversion of 99.63% was achieved after 3 hrs and a conversion of 99.81% was achieved after 6 hrs.
Many variations will suggest themselves to those skilled in this art in light of the above detailed description. All such obvious modifications are within the full intended scope of the appended claims.

We claim:
1. A process for the synthesis of aliphatic amino acid salts comprising hydrolyzing lactam in an aqueous media in the presence of alkali, wherein the temperature is in the range of 85 - 90°C, the reaction time is 3 - 6 hours and the molar ratio of the alkali : lactam is 1.2:1-1.3:1.
2. The process as claimed in claim 1, wherein the temperature is preferably 85°C.
3. The process as claimed in claim 1, wherein the alkali is sodium hydroxide.
4. The process as claimed in claim 1. wherein the aqueous media is water.
5. The process as claimed in claim 1, wherein the lactam is selected from the group butyrolactam, vaJerolactam, epsilon-caprolactam, beta-propiolactam or delta-valero lactam.