INTERCONVERSION BETWEEN ISOMERIC P-MENTHANE-3-CARBOXYLIC ACIDS
A process for interconversion between WS-1 and neo-WS-1 by heating to a temperature in a range of from 60 degrees Celsius to 250 degrees Celsius. The heating can be done in the presence of an acid catalyst. Starting from practically pure (=98%) WS-1, or mixtures of WS-1 and neo-WS-1, practically pure (=98%) neo-WS-1 can be obtained. Starting from practically pure (=98%) neo-WS-1, or mixtures of WS-1 and neo-WS-1, practically pure (=98%) WS-1 can be obtained.
1 . A process for interconversion between WS-1 and neo-WS-1, the process comprising exposing a reaction mixture comprising a starting composition selected from the group consisting of WS-1, neo-WS-1, and mixtures thereof, to a temperature greater than or equal to 60 degrees Celsius.
2 . The process of claim 1 , wherein the temperature is in a range of from 60 degrees Celsius to 250 degrees Celsius.
3 . The process of claim 1 , wherein the temperature is in a range of from 150 degrees Celsius to 220 degrees Celsius.
4 . The process of claim 1 , wherein the reaction mixture further comprises an acid catalyst.
5 . The process of claim 4 , wherein the acid catalyst is a Brφnsted acid.
6 . The process of claim 5 , wherein the Brφnsted acid is selected from the group consisting of p-toluenesulfonic, sulfosalycilic, benzenesulfonic, methanesulfonic, triflic, sulfuric, phosphoric, perchloric, and combinations thereof.
7 . The process of claim 4 , wherein the acid catalyst is a Lewis acid.
8 . The process of claim 7 , wherein the Lewis acid is selected from the group consisting of zinc bromide, zinc chloride, boron trifluoride, ferric chloride, lithium perchlorate, and combinations thereof.
9 . The process of claim 1 , wherein the starting composition comprises greater than or equal to 98% by weight WS-1.
10 . The process of claim 1 , wherein the starting composition comprises greater than or equal to 98% by weight neo-WS-1.
11 . The process of claim 1 , wherein the starting composition comprises a mixture of WS-1 and neo-WS-1 in any ratio.
12 . The process of claim 1 , wherein the process produces a product comprising greater than or equal to 98% by weight neo-WS-1.
13 . The process of claim 1 , wherein the process produces a product comprising greater than or equal to 98% by weight WS-1.
14 . The process of claim 1 , wherein the process produces a product, and the process further comprises isolating WS-1 from the product by a method selected from the group consisting of distillation, crystallization, and combinations thereof.
15 . The process of claim 1 , wherein the process produces a product, and the process further comprises continuously removing neo-WS-1 from the product by distillation.
16 . The process of claim 1 , wherein the process produces a product containing WS-1 and neo-WS-1 in a ratio respectively of 7.3±1.0.
17 . A method comprising
heating a starting composition comprising greater than or equal to 98% by weight WS-1 in a reaction zone to a temperature of from 60 degrees Celsius to 250 degrees Celsius, to convert at least a portion of the WS-1 to neo-WS-1; and
removing neo-WS-1 from the reaction zone by distillation to obtain a product composition comprising greater than or equal to 98% by weight neo-WS-1.
18 . The method of claim 17 , wherein the heating is conducted in the presence of an acid catalyst.
19 . A method comprising
heating a starting composition comprising a mixture of neo-WS-1 and WS-1 in any ratio to a temperature of from 60 degrees Celsius to 250 degrees Celsius to make an intermediate composition;
isolating WS-1 from the intermediate composition by a method selected from the group consisting of distillation, crystallization, and combinations thereof to obtain a product composition comprising greater than or equal to 98% by weight WS-1.
20 . The method of claim 19 , wherein the heating is conducted in the presence of an acid catalyst