Patent GB-989476-A (GB)
Title: Process for the preparation of cyclic carboxylic acids and their esters
IPC: C11B9/00
Filed: 1964-01-17
Abstract: A process for the preparation of cycloalkane and cycloalkene carboxylic acids and their esters of the formula <FORM:0989476/C2/1> wherein Y and Z are each hydrogen or together represent a single bond, R is hydrogen or lower alkyl, and A is an alkylene radical containing more than three carbon atoms between the two indicated valence bonds, comprises reacting a sulphonic ester of the formula <FORM:0989476/C2/2> wherein X represents hydrogen or halogen and B represents a hydrocarbon radical, with an alkali metal hydroxide or alkoxide in an organic or aqueous organic medium.  Compounds claimed per se cyclopentadecane carboxylic acid and methylcyclopentadecane carboxylate.  Preferably A is a polymethylene radical -(CH2)n-, optionally substituted by one or more lower alkyl, especially methyl, radicals, n being an integer higher than 3, preferably 5 to 16, and B is preferably a lower alkyl radical or a mononuclear aryl radical, especially phenyl or (lower alkyl) phenyl.  As the sulphonic ester it is most convenient to use methanesulphonic (or mesyl) or toluene-p-sulphonic (or tosyl) esters.  As alkali metal hydroxide or alkoxide, it is preferred to use the hydroxides and alkoxides of sodium or potassium.  When the former is used the reaction medium is preferably a lower alkanol, for example methanol, ethanol, propanol or butanol, either in anhydrous form or mixed with water.  When an alkali metal alkoxide is used the reaction medium may be an anhydrous lower alkanol, i.e. methanol, ethanol, propanol or butanol, but is preferably the alcohol corresponding to the alkoxide employed or a non-polar organic liquid, for example a saturated liquid aliphatic or cycloaliphatic hydrocarbon such as heptane, cyclohexane or methylcyclohexane, or a mononuclear aromatic hydrocarbon such as, for example, benzene or toluene, or mixtures of these solvents, more especially mixtures of alcohol and aromatic hydrocarbon.  The product of the reaction is an ester of Formula I which can be separated by the application of appropriate known methods.  The acids may be converted into the corresponding esters by known methods of esterification. Alternatively, the esters may be converted into the corresponding acids by saponification using the usual methods of saponifying carboxylic acid esters.  The sulphonic esters may be made by reacting an acyloin, with either a sulphonic acid or a sulphonic acid chloride, for example tosyl chloride or mesyl chloride.  The keto-ester formed may be extracted from the reaction product with a solvent such as benzene.  The halo-esters may be prepared by reacting the corresponding unsubstituted keto-esters with a halogen, preferably bromine, in equimolecular quantities, the operation being preferably carried out in an organic solvent medium which is inert under the operating conditions, e.g. a mononuclear aromatic hydrocarbon (such as benzene or toluene) or a halogenoalkane such as carbon tetrachloride.  In an example 2-oxy-cyclohexadecyl tosylate is refluxed with potassium hydroxide to produce cyclopentadecane carboxylic acid which may be esterified with methanol in the presence of sulphuric acid.  The starting material is prepared by reacting cyclohexadecane - 2 - ol - 1 - one with toluene - p - sulphonyl chloride.  In another example 2-bromo - 12 - tosyloxy - cyclododecanone is refluxed with potassium hydroxide to produce cycloundec-1-ene carboxylic acid.  The starting material is prepared by direct bromination of 2-oxycyclododecyl tosylate.