Carbon dioxide elimination from formyloxyalkynes - to give alkynyl esters,alkynes and allenes

摘要

is split off from a cpd. of formula: R4CH(OCHO)-C triple bond C-CR1R2R3 (where R1 is H, 1-6C alkyl or OCOR5; R2-R5 are H or 1-6C alkyl; and when R1 = OCOR5, R2 = H) by contacting at 140-260 degrees C with a finely-divided gp. Ib metal (pref. Cu) and/or Cd or Zn and/or Ni, Pd or Pb or Pt or a cpd. of these metals which liberate the free metal under the reaction conditions. The prodts. are alkynyl formates, alkynyl alkanoates, alkynes and the corresp. isomeric allenes. The prodts. are intermediates, e.g. for insecticides, acaricides, corrosion inhibitors, vitamin E and plant growth promoters.