Patent GB-684441-A (GB)
Title: Improvements in or relating to the stabilisation of mixtures of hydrogen halides and olefinically unsaturated organic compounds
IPC: C07C7/20
Filed: 1950-11-24
Abstract: Mixtures of olefinic compounds and hydrogen halides are stabilized against interaction during transport, storage or fractionation by incorporating a small proportion of an amine, imine, their hydrohalide salts, a nitrile, isonitrile or hydrosulphide.  Olefinic compounds include alkyl, aralkyl, and alicyclic hydrocarbons and their substitution or addition products, e.g. ethylene, butadiene, cyclohexene, hexadiene and their homologues.  Amines used as inhibitors include primary, secondary or tertiary saturated or unsaturated amines, alkyl, aryl, aralkyl, alicyclic, and heterocyclic amines, and guanidine, being specified.  Substituted amines include chlor-amines, hydroxy-amines, amino-acids, amino-phenols, urea, and thiourea. Representative imines, nitriles, and isonitriles include hydrogen cyanide, cyanogen chloride, and substituted derivatives such as chlor, amino, and hydroxy nitriles.  Hydrosulphides include hydrogen sulphide, and thiols which may contain substituents such as hydroxy, halogen, and carboxy.  Alkane nitriles and thiols are preferred additives.  The amount of inhibitor may be only 1-10 but is preferably 25-2000 p.p.m.  With continuous fractionation, it may be added continuously near the top of the column.  In examples, mixtures of hydrogen chloride and propylene are fractionated at 15.8 atm. with a head temperature of - 18 DEG  and reboiler temperature of 41 DEG C. using a nickel lined or a stainless steel column.  The reduction in isopropyl chloride formation by addition of acetonitrile, methane thiol, and N,N-dimethylaniline is shown and compared with that where water is added. Acetonitrile may be replaced by tetradecane nitrile, benzonitrile, ethyl isocyanide, isopropane thiol, octane thiol, benzene thiol, 3,5-xylidine, n-decylamine, pyridine, n-hexadecylamine, dicyclohexylamine hydrochloride, tri - n - butylamine, N - isopropylidene - aniline or -ethylamine.  The reduction in the conversion of hydrogen chloride and propylene to isopropyl chloride when contacted with nickel hydrochlorination catalysts, by adding acetonitrile, a mixture of hexadecane, octadecane, and octadecene nitriles, or amines specified above, is also exemplified.ALSO:Mixtures of olefinic compounds and hydrogen halides are stabilized against interaction during fractionation by incorporating a small proportion of an amine, imine, their hydrohalide salts, a nitrile, isonitrile or hydrosulphide. Olefinic compounds include alkyl, aralkyl and alicyclic hydrocarbons and their substitution or addition products, e.g. ethylene, butadiene, cyclohexene, hexadiene and their homologues. Amines used as inhibitors include primary, secondary or tertiary, saturated or unsaturated amines, alkyl, aryl, aralkyl, alicyclic, and heterocyclic amines, and guanidine, being specified. Substituted amines include chlor-amines hydroxyamines, amino-acids, amino-phenols, urea, and thiourea.  Representative imines, nitriles, and isonitriles include hydrogen cyanide, cyanogen chloride, and substituted derivatives such as chlor, amino, and hydroxy nitriles.  Hydrosulphides include hydrogen sulphide, and thiols which may contain substituents such as hydroxy, halogen, and carboxy.  Alkane nitriles and thiols are preferred additives.  The amount of inhibitor may be only 1-10, but is preferably 25-2000 p.p.m.  With continuous fractionation, it may be added continuously near the top of the column.  In examples, mixtures of hydrogen chloride and propylene are fractionated at 15.8 atm., with a head temperature of -18 and reboiler temperature of 41 DEG C using a nickel lined or a stainless steel column.  The reduction in isopropyl chloride formation by addition of acetonitrile, methane thiol, and N, N-dimethylaniline is shown and compared with that when water is added. Acetonitrile may be replaced by tetradecane nitrile, benzonitrile, ethyl isocyanide, isopropane thiol, octane thiol, benzene thiol, 3, 5-xylidine, n-decylamine, pyridine, n-hexadecylamine, dicyclohexylamine hydrochloride, tri-n-butylamine, N-isopropylideneaniline or -ethylamine.