Abstract: A process for the preparation of an ester of furan of the formula ##STR1## or ##STR2## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each hydrogen or hydrocarbon radicals containing at least one heteroatom comprising subjecting an ester of the formula ##STR3## wherein R.sub.5 is hydrogen or a hydrocarbon radical containing at least one heteroatom to a transesterification reaction with a furan alcohol of the formula ##STR4## in the presence of a catalyst comprising an alkaline carbonate other than lithium carbonate at a temperature of 0.degree. C. to 90.degree. C.

Abstract: The invention concerns a process transforming an aldehyde into a corresponding alkene, of the type wherein the aldehyde is placed in the presence of a phosphoric reagent and a base in an organic solvent.The process consists in using an alcohol as the solvent and as a base a mineral base which in an aqueous medium evinces a basic strength equal to or less than that of the hydroxide ion, or a strongly basic organic base of the amine family, and in limiting the hydration rate of the reaction medium to a value at most of 10 moles of water per mole of aldehyde.

Abstract: The invention relates to a process for converting an aldehyde into a corresponding alkene and of the type wherein the aldehyde is placed in the presence of a phosphoric reagent and a base in solution in an organic aprotic solvent; the process comprising using a mineral base evincing in an aqueous medium a basic force less than or equal to that of the hydroxide ion or a strongly basic organic base of the nitrogen compounds family and adjusting the hydration rate of the reaction medium in such a manner that there are about 0.5 to 5 moles of water per mole of aldehyde.