Patent GB-635348-A (GB)
Title: Improvements in or relating to beta-substituted carboxylic acid compounds and methodof preparing same
IPC: C07C319/14
Filed: 1946-09-04
Abstract: In the reaction between a saturated aliphatic b -lactone and an inorganic salt in a polar solvent reaction medium to give salts of b -substituted carboxylic acids if excess lactone is present, b -substituted polyacyloxy-carboxylic acid salts are obtained which may be converted to the corresponding free acid on treatment with acid of Specification 635,347.  For details of salts and lactones employed (see Group IV (b)).  Specification 639,679, [Group IV (b)] also is referred to.  The Specification as open to inspection under Sect. 91 is not restricted to the use of saturated aliphatic lactones but also specifies aromatic and unsaturated aliphatic lactones which may be substituted with groups containing halogens, nitrogen, oxygen or sulphur.  This subject-matter does not appear in the Specification as accepted.ALSO:Salts of b -substituted carboxylic acids are obtained by reacting b -lactones of the general formula <FORM:0635348/IV (b)/1> where R1, R2, R3 and R4 may be hydrogen or alkyl groups, with inorganic salts other than sulphides and hydrosulphides whose use is disclosed in Specification 639,679, which are ionizable in a polar solvent reaction medium.  They are converted to the corresponding free acid on acidification.  The use of salts which are strong oxidizing agents, e.g. persulphates, chlorates, perchlorates, bromates, iodates and hypochlorites is not preferred since oxidation may accompany the main reaction to give a variety of organic products.  With certain oxy-acid salts, e.g. sodium bicarbonate and thiosulphate, the carboxylic acid salt first formed is unstable, being hydrolysed in situ to a b -hydroxy carboxylic acid which is obtained as a salt, thus b -propiolactone with sodium bicarbonate yields sodium hydracrylate.  Water is the preferred solvent, others mentioned being alcohols, carboxylic acids and nitro-paraffins. Alkali metal and ammonium salts are preferred although alkali earth and other metal salts may be used. A molecular excess of salt is required to minimise the production of poly-compounds obtained by the reaction disclosed in Specification 635,347.  Reaction conditions specified include the use of 1-10 mols. of lactone, preferably 1 mol., to 1-10 mols. of salt, temperatures below 100 DEG  C., preferably between -25 DEG  and 50 DEG  C., and pH's of 2-10.  Anions of the salts may be derived from halogens, chalcogens, nitrogen, phosphorus, carbon, boron and silicon, and salts instanced are those containing monovalent, e.g. halides and thiocyanates, and divalent anions which latter may react with more than one mol. of b -lactone, e.g. borates, bromates, carbonates, bicarbonates, nitrates, nitrites, phosphates, phosphites, silicates, sulphates, bisulphates, persulphates, sulphites, thiosulphates, thiocarbonates and sulphoxylates.  b -Propiolactone is the preferred lactone whilst others mentioned are b -butyro-, b -isobutyro-, b -valero-, b -isovalero-, b -n-capro-, a  - ethyl - b  - propio-, a  - isopropyl - b  - propio -, a  - butyl - b  - propio-, a  - methyl - b  - butyro - a  - ethyl - b  - butyro - and b  - methyl - b  - valero - lactone. It is stated that b -propiolactone reacts with aqueous sodium nitrite to give on acidification b -nitro-propionic acid with some of the nitrate and similarly with sodium nitrate to give the nitric acid ester of b -hydroxy propionic acid.  In examples: b -propiolactone is reacted in aqueous solution to produce on acidification b -chloro-propionic acid with (1) and (2) sodium chloride; (3) and (4) sodium chloride with a small amount of hydrogen chloride; (5) lithium chloride; (6) ammonium, potassium, barium and calcium chlorides, b -bromo-propionic acid with (6) potassium and sodium bromides, b -iodo-propionic acid with (6) potassium and ammonium iodides, b -fluoro-propionic acid with (6) sodium fluoride, b -cyano-propionic acid with (7) sodium cyanide, b -thiocyano-propionic acid with (8) sodium thiocyanate, thiohydracrylic and b -dithio-dipropionic acid with (9) sodium thiosulphate, and b -sulpho-propionic acid with (10) ammonium sulphite.  Specification 649,028 also is referred to.  The Specification as open to inspection under Sect. 91 is not restricted to the use of aliphatic saturated b -lactones but also specifies lactones of b -hydroxy-monocarboxylic acids containing cycloalkyl, aryl and aralkyl substituents, lactones of unsaturated b -hydroxy-carboxylic acids, mono- and di-b -lactones of di-carboxylic acids and b -lactones containing oxygen, nitrogen, sulphur and halogens combined in such groupings as nitro, ether, amino and hydroxy, as well as the carbonoxy structure and hydrogen atoms.  This subject-matter does not appear in the Specification as accepted.