Patent GB-754763-A (GB)
Title: Production of acrylamide
Inventor: JONES GIFFIN DENISON
IPC: C07C233/09
Filed: 1954-05-05
Abstract: Acrylamide is separated from an aqueous solution comprising acrylamide and sulphuric acid by contacting the solution with a granular cation exchange resin, whereby the acrylamide is absorbed by the resin and the sulphate radicals are left in the surrounding liquid, separating the resin from the surrounding liquid and washing it with water to extract the acrylamide therefrom.  In the preferred embodiment of the invention the aqueous solution comprising acrylamide and sulphuric acid is prepared by reacting water with acrylonitrile in the presence of sulphuric acid, the water content of the aqueous solution is brought to a point such that the sulphuric acid has a concentration of not more than 70 per cent by weight and the resulting solution is fed to a water immersed bed of the cation exchange resin to displace water from the bed, water is thereafter fed to the bed to displace a further amount of liquid from the bed, and the displaced effluent liquid is collected as successive fractions whereby a fraction is obtained which contains a major portion of the sulphate radicals and a subsequent fraction is obtained which contains a major portion of the acrylamide.  The aqueous acrylamide solution from the above processes may then be contacted with an anion exchange resin in other than its sulphate or acrylate form whereby any remaining sulphuric or acrylic acids are chemically removed.  Further contact of the aqueous acrylamide solution with the acidic form of a cation exchange resin may then be brought about to remove ammonia and ammonium ions.  This latter chemical treatment may precede the treatment with an anion exchange resin.  It is stated that acrylic acid, which is usually formed in minor amounts during the preparation of acrylamide from acrylonitrile as described above, is absorbed together with the amide in the cation exchange resin, but that during the water washing step the acrylic acid tends to be extracted before the amide so that it is possible to obtain successive fractions of effluent liquid which are rich in acid and amide respectively.  Preferred cation exchange resins for absorbtion of acrylamide are those containing sulphonate radicals such as sulphonated phenol-formaldehyde resins, and sulphonated copolymers of monovinyl and polyvinyl aromatic hydrocarbons.  The resin is preferably used in its acidic form but it may be in the form of a salt such as an ammonium or an alkali metal salt. Suitable anion exchange agents are the resinous condensation products of phenol, formaldehyde and polyethylene-polyamines and the reaction products of amines such as trimethylamine or dimethylethanolamine with a chloro-methylated copolymer of styrene, ar-ethylvinyl benzene and divinylbenzene.  In examples (1) the solution obtained from the reaction of acrylonitrile with aqueous sulphuric acid in the presence of copper powder at 100 DEG  C. is fed to a column of a waterinsoluble ammonium salt of a sulphonated copolymer of styrene, ar-ethylvinyl benzene and divinyl benzene immersed in water, water is then fed to the column and the displaced effluent liquid is collected as fractions, consisting of successively water, ammonium bisulphate solution and acrylamide solution; (2) the operations of Example 1 are amplified by the use of a cycle of recovery operations to obtain fractions of acrylamide solution of increasing concentrations; (3) the solution obtained by heating acrylamide bisulphate and water is fed to a column of the acidic form of the resin used in Example 1, water is then fed to the column and the displaced effluent fractions consist successively of water, aqueous sulphuric acid, water, acrylic acid and acrylamide together, and nearly pure acrylamide solution. Specification 631,592 is referred to.