FIELD: chemistry.
SUBSTANCE: invention relates to an improved method of producing ethylenically unsaturated acids and esters thereof of the following formula: R3-C(=(CH2)m)-COOR4 , where R3 and R4 each independently represent hydrogen or an alkyl group, and m equals 1, by reacting alkanoic acid or an alkanoic acid ester of formula R3-CH2-COOR4, where R3 and R4 each independently represent hydrogen or an alkyl group with a methylene or ethylene source of formula 
, where R5 and R6 are independently selected from C1-C12 hydrocarbon groups or H; X is O or S; n is an integer from 1 to 100; and m equals 1, in the presence of a catalyst system to an ethylenically unsaturated acid or ester as a product, where the product in form of an acid or ester is then brought into contact with a dienophile to eliminate the undesirable colour of the product, where the dienophile is a compound of formula: 
where Z is selected from a group consisting of -C(O)Y, -CN, -NO2 or halogen; Y is selected from a group consisting of hydrogen, alkyl, hetero, -OR, halogen or aryl; R, R1 and R2 independently denote hydrogen, alkyl or aryl, and hetero denotes N, S or O. The heteroatoms can be unsubstituted or substituted with one or more groups consisting of hydrogen, alkyl, -OR, aryl, aralkyl or alkaryl, where R is as defined for Y; Z' can denote any group selected above for Z, or can also denote hydrogen, alkyl, aryl or hetero; or Z and Z1 together can form a -C(O)Y(O)C- group so that the dienophile forms a cyclic group of formula 
, where R1 and R2 are as defined above, Y is hetero as defined above, or Y is an alkylene group of formula -(CH2)s-, where s equals 1, 2 or 3.
EFFECT: obtained products comes into contact with a dienophile to eliminate the undesirable colour of the product.
37 cl, 2 dwg, 10 tbl
