Imides of the formula <;FORM:0802741/IV (b)/1>; where R is C1-C10 alkyl, R1 is H or methy and n is 0-7, are prepared by reacting bicyclo-(2:2:1) - 5 - heptene - 2:3 - dicarboxylic anhydride with an amine <;FORM:0802741/IV (b)/2>; at 100-160 DEG C., preferably in the presence of an inert volatile organic solvent. The amines are prepared by adding acrylonitrile to the appropriate hydroxy compound to give <;FORM:0802741/IV (b)/3>; and catalytically hydrogenating the latter. Examples are given of the various stages of the process where (1) R is butyl and n is zero; (2) R is 2-ethylhexyl and n is zero; (3) R is hexyl, R1 is H and n is 1, 2 or 6; and (4) R is hexyl, R1 is methyl and n is 1. Many other products are mentioned. Specification 790,841 is referred to.ALSO:Insecticidal compositions contain an active ingredient and as extender or synergist therefor an imide of the formula <;FORM:0802741/VI/1>; where R is C1-C10 alkyl, R1 is H or methyl and n is 0-7. As much as 75 per cent of the active ingredient in a fly-spray composition can be replaced by the synergist, in the weight ratio of 1-80 parts for each part of active ingredient replaced. A typical composition contains 15-85 mg. of active ingredient per 100 c.c. of base, and 10-40 parts of synergist per part of active compound. The latter may be 3-(2-cyclopentenyl) - 2 - methyl - 4 - oxo - 2 - cyclopentenyl chrysanthemumate as in Specification 790,841. The compositions may be prepared as concentrates and diluted with water, oil or petroleum for use against insects and to protect agricultural crops, stored grain and packaged goods.;FORM:0802741/VI/1>;FORM:0802741/IV>;FORM:0802741/IV>;FORM:0802741/IV>