Patent GB-655387-A (GB)
Title: Improvements in or relating to alpha-beta unsaturated monocarboxylic acids and method of producing same
IPC: C07C51/09
Filed: 1947-07-17
Abstract: Polymers of lactones having the general formula <FORM:0655387/IV (a)/1> wherein R1, R2, R3 represent hydrogen atom or hydrocarbon groups free from ethylenic or acetylenic unsaturation, are prepared by subjecting the monomeric lactones to the action of heat, pressure, actinic light or a condensation catalyst; the higher molecular weight lactones require heating for some hours in the presence of the catalyst.  Solutions of the monomers may be polymerized.  The products generally have a molecular weight of from about 500 to 2000. In examples: (1) hydracrylic acid lactone with a trace of potassium carbonate is heated to about 100-130 DEG  C. to form a semi-solid mass; (2) b -hydroxy butyric acid lactone is similarly treated. Numerous other lactones are mentioned containing alkyl, aralkyl, aryl and cycloalkyl groups. Many condensation catalysts including Friedel-Crafts, alkaline and acidic compounds are also mentioned. The polymers are subjected to pyrolysis, yielding a :b -unsaturated monocarboxylic acids (see Group IV (b)).  The Specification as open to inspection under Sect. 91 refers to the polymerization of b -lactones of monocarboxylic acids in general, having at least one hydrogen atom attached to the a -carbon atom and states that reactive hydrocarbon substituents, e.g. vinyl, divinyl and acetylinic substituents are preferably not present.  Suitable lactones are said to be those obtained by reaction of an aldo-ketene, e.g. ketene, methyl ketene or ethyl ketene with a compound containing the carbonyl group as the sole functional group, e.g. formaldehyde, acetaldehyde, propionaldehyde, furfural, acetone or methyl ethyl ketone.  This subject-matter does not appear in the Specification as accepted.ALSO:Alpha-beta unsaturated monocarboxylic acids are prepared by heating a polymer of a b -lactone of a monocarboxylic acid having the general formula <FORM:0655387/IV (b)/1> in which R1, R2 and R3 represent hydrogen atoms or hydrocarbon groups free from ethylenic or acetylenic unsaturation and which are not necessarily identical, to a temperature above its decomposition temperature but below the decomposition temperature of the desired unsaturated acid. In a modification, the said b -lactone in monomeric form is heated to a temperature sufficient to effect polymerization of the monomer and simultaneous pyrolysis of the polymer but below the decomposition temperature of the desired unsaturated acid.  The monomeric lactone may first be polymerized and the polymer then pyrolysed as above. Pyrolysis temperatures of 150 DEG  to 300 DEG  C. are mentioned. Atmospheric or reduced pressure may be employed.  In the modification, the monomeric lactone may be passed over a heated condensation catalyst in a tube or tower; thus, hydracrylic acid lactone may be passed over heated zinc chloride at 200 DEG  C., yielding acrylic acid directly.  The polymerization of the lactones may be effected, in the case of the low molecular weight lactones, by means of heat, pressure, actinic light or a condensation catalyst and in the case of the higher lactones, by heating for several hours in the presence of the catalyst (see Group IV (a)).  In examples: (1) hydracrylic acid lactone with a trace of potassium carbonate is heated to about 100-130 DEG  C. until a semi-solid mass is obtained and this is heated under 8-10 mm. pressure and at a temperature of 150-175 DEG  C., acrylic acid distils off; (2) b -hydroxy-butyric acid lactone is treated as in (1) and the resulting polymer heated at 180-190 DEG  C., whereupon crotonic acid distils off.  Reference is made to the formation of b  : b -dimethyl acrylic acid from b -hydroxy isovaleric acid lactone, a -methyl acrylic acid from a -methyl hydracrylic acid lactone and cinnamic acid from b -phenyl hydracrylic acid lactone. Numerous other lactones are mentioned containing as an " R " radical an alkyl, cycloalkyl or aralkyl group. The Specification as open to inspection under Sect. 91 refers to the use of lactones of monoboxylic acids having at least one hydrogen atom on the a -carbon atoms and preferably not containing reactive hydrocarbon substituents, e.g. vinyl, divinyl or acetylenic groups and mentions lactones prepared by reacting an aldo-ketene such as ketene, methyl ketene or ethyl ketene with a low molecular weight compound containing a carbonyl group as the sole functional group, e.g. formaldehyde, acetaldehyde, propionaldehyde, furfural, acetone or methyl ethyl ketone.  This subject-matter does not appear in the Specification as accepted.