Patent GB-822731-A (GB)
Title: Production of acrylic acid and derivatives thereof
IPC: C07C69/54
Filed: 1956-06-22
Abstract: Acrylic acid or a derivative thereof is prepared by interacting acetylene, carbon monoxide and water or an organic compound having a removable hydrogen atom bound to an oxygen, sulphur or nitrogen atom at a temperature between 100 DEG  and 250 DEG  C. under a pressure of 5 to 100 atmospheres in the presence as catalyst of a complex formed from a chloride, bromide or iodide of an element of the iron group and at least one complex-forming compound containing two elements, the same or different, of the series consisting of oxygen, nitrogen and sulphur and having the general formula X-CH2-(CH2)n-Y in which X and Y are hydroxy, alkoxy, aryloxy, organic acyl or thiol groups or the radicals of aliphatic mercaptans, thiophenols, thiocarboxylic acids or non-tertiary amines, the free valency of the radical being at the sulphur, oxygen or nitrogen atom thereof, and n represents zero, 1 or 2.  The organic compounds having replaceable hydrogen may be alcohols, primary or secondary amines, carboxylic acids or mercaptans and reference is made to saturated and unsaturated primary, secondary or tertiary alcohols; aliphatic, aromatic, araliphatic and cycloaliphatic polyhydric alcohols; enolisable ketones.  The catalytic complexes may be preformed by vigorous mixing or heating of the components, e.g. by shaking a concentrated aqueous solution of nickel halide with the organic complexing compound; the complexes are generally green or blue crystalline compounds containing 2-3 mols. of organic component. The complexes may be introduced into the reaction as a solution, for example, in a liquid reactant, a hydrocarbon, an ether or a ketone, or on a carrier such as pumice or silica gel. Alternatively, the complex may be formed from its components in situ using stoichiometric amounts or an excess of either.  The catalyst used may amount to 0.5-35 per cent by weight of the organic compound having replaceable hydrogen.  The carbon monoxide may contain inerts such as nitrogen, carbon dioxide or hydrogen.  Inert solvents such as acetone, dimethyl formamide, tetrahydrofuran, butyrolactone or N-methyl pyrrolidone may be present.  The process may be operated in the gaseous or liquid phase and continuously or discontinuously.  Examples describe (1), the batchwise preparation of acrylic acid or its methyl, ethyl or n-butyl ester from water or the appropriate alcohol using as catalysts mixtures of nickel bromide and 1 : 2-diethyl mercapto ethane, N : N1-tetramethyl ethylene diamine, beta-ethyl mercapto-diethyl ether, dimethyl amino-acetone, 1-ethyl mercapto-3-(dimethylamino)-propane, 1-ethyl mercapto-2-(dimethyl amino) - ethane, beta - (dimethyl-amino)-diethyl ether, 1 : 3-di-methylmercapto propane, acetyl acetone or benzoyl acetone, the complex being preformed in some cases and in certain preparations acetone or tetrahydrofurane is present as a diluent, while hydroquinone may be present in the acrylic acid synthesis; (2) the continuous preparation of methyl or butyl acrylate by feeding CO, C2H2, the appropriate alcohol, nickel bromide and acetyl acetone into an autoclave at 180-210 DEG  C. under a pressure of 28-30 atmos. and withdrawing the products continuously via a pressure release device.  Other organic complex forming compounds specified are 1 : 2-dimethyl mercapto ethane, 4-dimethyl amino-butanone-2, 1 - ethoxy - 2 - dimethyl amino ethane, acetonyl acetone, N,N1-tetramethyl propylene diamine and 1-ethyl mercapto-2-ethoxy ethane.