Patent GB-772196-A (GB)
Title: Improvements in or relating to preparation of acrylamide
IPC: C07C233/09
Filed: 1954-11-22
Abstract: Acrylamide is prepared by first reacting at a temperature between 20 DEG  C. and 100 DEG  C. in the liquid phase acetylene, nickel carbonyl, a reactive acid to react with nickel carbonyl to form a nickelous salt of the acid (defined as hydrochloric or hydrobromic acid, or an aliphatic monocarboxylic acid which may be unsaturated and contains up to 4 carbon atoms), using an aliphatic monocarboxylic acid as defined above when ammonia is used as the compound having reactive hydrogen, and ammonia or other compound having reactive hydrogen (defined as water, a carboxylic acid, an alcohol, a mercaptan or a primary or secondary amine), and while these are reacting introducing into the reaction mixture and there reacting at a temperature between 20 DEG  C. and 100 DEG  C., preferably between 50 DEG  C. and 90 DEG  C., acetylene, carbon monoxide and ammonia. The free carbon monoxide may supply between 20 and 80 per cent, preferably 45 to 70 per cent of the total carbon monoxide available both from the free carbon monoxide and the nickel carbonyl.  The amount of reactive acid used may be about equivalent to the nickel present to form a nickelous salt and it is preferred to use within about 20 per cent molar equivalency of the acid.  The acetylene may be used in a molar quantity equivalent to the total carbon monoxide available within 10 per cent although a quantity of acetylene up to about 20 per cent molar excess may be used.  The quantity of ammonia used may be in molar excess or about molar equivalent to the total carbon monoxide available, a molar ratio of ammonia to total carbon monoxide from about 0.95:1 to 1.1:1 being preferred.  Suitable reactive aliphatic monocarboxylic acids are formic, acetic, propionic, butyric, propiolic, acrylic, methacrylic, crotonic, hydroxyacetic and ethoxyacetic acids.  The carboxylic acid used in the second stage of the process may be the same as that used in the first stage.  A reactive aliphatic carboxylic acid, e.g. acrylic acid, may be used in the first stage to initiate the reaction, and then such acid may be replaced with hydrochloric or hydrobromic acid. The alcohol used as the compound having reactive hydrogen may be an alkanol, preferably one containing up to 4 carbon atoms, including primary, secondary and tertiary alkanols, e.g. methyl, ethyl or butyl alcohol.  The process is preferably carried out in an inert solvent, e.g. acetone, methyl ethyl ketone, dioxane, ethyl ether, isopropyl ether, benzene, toluene, xylene, dimethyl ethers of the ethylene glycols, methyl and ethyl ether esters of the glycols, dimethyl formamide, and mixtures thereof.  The process may be carried out in a continuous manner by first reacting the acetylene, nickel carbonyl, reactive acid, and compound having reactive hydrogen, then imposing on this reaction the reaction of acetylene, carbon monoxide and ammonia, introducing continuously reacting proportions of acetylene, nickel carbonyl, reactive acid, e.g. acrylic acid, and ammonia, and continuously withdrawing reaction mixture.  The withdrawn reaction mixture may preferably be treated with acetylene and ammonia, if needed in the presence of acid, to react with any remaining nickel carbonyl.  A polymerization inhibitor may be used during the forming of acrylamide and/or during its purification and isolation, e.g. pyrogallol, tannic acid, hydroquinone, monoalkyl ethers of hydroquinone, di-b -naphthol, picric acid, p-hydroxydiphenylamine, copper, copper salts, and mixtures thereof.  A number of detailed examples are given.