Abstract: There is disclosed a method of producing ?,?-unsaturated carboxylic acid of formula (3) wherein R1 denotes a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkenyl group or an alkynyl group, which method comprises reacting a carboxylic acid of formula (1) wherein R1 denotes the same as the above, or carboxylic anhydride of formula (2) wherein R1 denotes the same as the above, with a methylenating agent in a presence of a catalyst containing metal of Group 13 of the Periodic Table of Elements in the amount of not more than 5 weight %.

Abstract: There is disclosed a method of producing ?,?-unsaturated carboxylic acid of formula (3) wherein R1 denotes a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkenyl group or an alkynyl group, which method comprises reacting a carboxylic acid of formula (1) wherein R1 denotes the same as the above, or carboxylic anhydride of formula (2) wherein R1 denotes the same as the above, with a methylenating agent in a presence of a catalyst containing metal of Group 13 of the Periodic Table of Elements in the amount of not more than 5 weight %.

Abstract: The present invention relates to a process for producing an allyl sulfone derivative represented by the formula (3): wherein Ar is an optionally substituted aryl group, and the corrugated line means either one of E/Z geometrical isomers, or a mixture thereof, which is an intermediate for producing vitamin A, which process is characterized by reacting an aryl sulfinic acid or a salt thereof represented by the formula (2): ArSO2M  (2) wherein Ar is as defined above, and M is hydrogen atom, sodium atom or potassium atom, with an allyl halide derivative represented by the formula (1): wherein X is a halogen atom, and Ar and the corrugated line are as defined above.