Patent GB-891242-A (GB)
Title: Improvements in and relating to stabilisation of halohydrocarbons
IPC: C07C17/42
Filed: 1959-12-01
Abstract: Halogenated hydrocarbons, especially liquid chlorinated hydrocarbons of use in dry cleaning and degreasing containing 1-3 carbon atoms, such as chloroform, carbon tetrachloride, methyl chloroform, ethylene dichloride, perchlorethylene and particularly trichlorethylene, are stabilized by the incorporation of a salt of a weak acid and an organic substituted ammonium hydroxide.  The hydroxide may be substituted with 1, 2 or 3 organic radicals, such radicals suitably having 1-8 carbon atoms, for example alkyl, cycloalkyl, aryl, heterocyclic, alkenyl, or aralkyl groups, and the nitrogen may be present as a member of a heterocyclic ring.  The acid radical present is derived from an organic or inorganic acid having a dissociation constant at 25 DEG C. less than 2X10-2; suitable organic acids are those carboxylic acids or phenols having up to 10 carbon atoms, and suitable inorganic acids are carbonic, arsenic, selenions, stannic, but preferably nitrous acids.  In the example the following salts are used:-diisopropylammonium formate, acetate, 2-chlorophenoxide and nitrite, di-n-propylammonium acetate, diisobutylammonium acetate, dicyclohexylammonium nitrite, and N-methylmorpholinium acetate, but an exhaustive list of other suitable salts is supplied; these salts are suitably incorporated in the halogenated hydrocarbon in an amount of 0,01-0,3% by weight.  Various phenols, especially those boiling at 180 DEG -250 DEG C. such as phenol, thytrol, catechol, p-cresol, guaiacol, eugenol, isoeugenol and methyl salicylate; amines such as diethylamine, triethylamine, dipropylamine, dibutylamine, diisobutylamine, triisopropylamine, diethanolamine, triethanolamine, N-methyl morpholine, N-methylpyrrole, b -picoline, pyridine, and aniline; p  epoxides such as ethylene oxide, 1:2-propylene oxide, 1:2- and 2:3-butylene oxides, butadiene mono- and di-oxides, epichlorhydrin, glycidol, isobutylene oxide, 1:2-octylene oxide, styrene oxide, cyclohexene oxide and cyclopentene oxide; olefinically unsaturated compounds such as pinene, amylene, and diisobutylene; esters such as ethyl acetate; and alcohols such as methanol, ethanol, butanol, propanyl alcohol and allyl alcohol may also be included. Any such additive is individually present in an amount less than 2%, generally 0,001-0,5% by weight, by weight of the halogenated hydrocarbon and the sum total of such additives is less than 5%, and usually less than 2%, by weight thereof.ALSO:The stabilization of halogenated hydrocarbons, especially those containing 1-3 carbon atoms such as chloroform, carbon tetrachloride, methyl chloroform, ethylene dichloride, perchlorethylene and particularly trichlorethylene, is achieved by the incorporation of a salt of a weak acid and an organic substituted ammonium hydroxide, usually in an amount of 0.01%-0.3% by weight of the halohydrocarbon.  The ammonium hydroxide may be substituted with 1, 2 or 3 organic radicals, such radicals suitably having 1-8 carbon atoms, for example alkyl, aryl, cycloalkyl, heterocyclic, alkenyl, or aralkyl groups, and the nitrogen may be present as a member of a heterocyclic ring. The acid radical present is derived from an organic or inorganic acid having a dissociation constant at 25 DEG C. less than 2 X 10-2; suitable organic acids are those carboxylic acids or phenols having up to 10 carbon atoms, and suitable inorganic acids are carbonic, arsenic, selenious, stannic but preferably nitrous acids.  In the example the following salts are used: diisopropylammonium formate, acetate, 2 - chlorophenoxide, and nitrile, di-n-propylammonium and diiso-butylammonium acetates, dicyclohexylammonium nitrile, and N-methyl-morpholinium acetate, but an exhaustive list of other suitable salts is supplied. Various phenols, especially those boiling at 180 DEG C.-250 DEG C., such as phenol, thymol, catechol, p-cresol, guaiacol, eugenol, isoeugenol and methyl salicylate; amines such as diethylamine, triethylamine, dipropylamine, dibutylamine, diisobutylamine, triisopropylamine, diethanolamine, triethanolamine, N-methyl morpholine, N-methyl pyrrole, b -picoline, pyridine and aniline; epoxides such as ethylene oxide, 1 : 2-propylene oxide, 1 : 2- and 2 : 3-butylene oxides, butadiene mono- and di-oxides, epichlorhydrin, glycidol, isobutylene oxide, 1 : 2-octylene oxide, styrene oxide, cyclohexene oxide, and cyclopentene oxide; olefinically unsaturated compounds such as pinene, amylene, and diisobutylene; esters such as ethyl acetate; and alcohols such as methanol, ethanol, butanol, propargyl alcohol and allyl alcohol may also be included.  Any such additive is individually present in an amount less than 2%, generally 0.001%-0.5%, by weight of the halohydrocarbon, and the sum total of such additives is less than 5%, and usually less than 2%, by weight thereof.