Patent GB-979524-A (GB)
Title: Improvements in or relating to the production of allylic terpene esters
IPC: C07C67/10
Filed: 1961-03-17
Abstract: Terpene esters are prepared by treating an allylic terpene halide with a free carboxylic acid (which may contain minor amounts of the corresponding anhydride) and a base in the presence of a cuprous chloride or bromide catalyst, said base being capable of neutralizing and being sufficient in quantity to neutralize hydrogen halide formed from the treatment so that the halide salts so produced are removed from the reaction medium either by precipitation or by dissolution into an aqueous phase. (The expression "allylic terpene halide" used herein denotes allylic chlorides or bromides derived from terpenes in which the terpene allyl residue consists of 10 carbon atoms).  In modifications of the above process, the cuprous chloride catalyst may be produced in situ by the use of cuprous oxide or copper or mixtures of copper and a cupric compound, and the free carboxylic acid and the base may be replaced by an ammonium or amine salt of a carboxylic acid, e.g. a salt of triethylamine, cyclohexylamine, diamylamine, butanolamine or stearylamine, or a quaternary ammonium, amidine or thiouronium salt.  In a preferred embodiment, the base is the sodium or potassium salt of the same carboxylic acid as the free carboxylic acid used. The terpene halide may be acyclic or cyclic. Reaction may be effected both below and above room temperature, and inert solvents may be present.  Numerous examples are given of the preparation of terpene esters from, on the one hand, allylic halide derivatives of myrcene, dihydromyrcene, ocimene, alloocimene, d-limonene, 3-p-menthene, a -terpinene, mixed menthadienes, a -pyronene, b -pyronene, a -pinene and a -terpineol, and on the other hand the following carboxylic acids and bases:-acetic acid and acetate salts of triethylamine, triethanolamine, N, N-diethylcyclohexylamine, ammonia, sodium, potassium, magnesium, lead, copper (cupric), aluminium, lithium, barium, calcium and silver; formic, propionic, decanoic, oxalic, sebacic, fumaric, maleic, tartaric, citric, chloracetic, tall oil and furoic acids and their sodium salts; isobutyric acid and the triethylamine salt thereof; phthalic acid and potassium acid phthalate; acetic acid and trisodium phosphate, acetic acid and cuprous oxide, and acetic acid and "Permutit Deacidite" (Registered Trade Mark) anion exchange resin; lactic acid and sodium carbonate, and benzoic acid and sodium carbonate; 1-hydronopic acid and triethylamine, and 1-menthoxyacetic acid and triethylamine; ammonium acetate; the monotriethylamine salts of oxalic, phthalic, maleic and tartaric acids, and the reaction product of triethylamine (1 mole) and fumaric acid (2 moles).  In some examples, the esters are saponified to yield the corresponding terpene alcohols.  Mixtures of alcohols or esters are, in some cases, resolved by vapour phase chromatography. Comparative experiments are described wherein the cuprous halide catalyst is omitted or wherein cupric chloride or cuprous iodide is used as catalyst.  The terpenic allylic halides used as starting material are prepared by hydrohalogenation or halogenation of suitable terpenes.  Specification 979,523 and U.S.A. Specification 2,794,826 are referred to.