Verfahren zur Herstellung von Cyanamid-Dicarbonsaeureestern

Cyanamide dicarboxylates (some of which are novel) of the general formula ROOC.N(CN).COOR where R represents an aliphatic, cycloaliphatic, araliphatic or aromatic hydrocarbon radical or a heterocyclic radical, which may be substituted, are prepared by reacting alkali metal or alkaline earth metal salts of cyanamide with chloroformates of the formula Cl.COOR in the presence of 0.1 to 10% by weight (based on the chloroformate) of a tertiary organic base and also in the presence of a two-phase, aqueous-organic reaction medium, at a temperature ranging from - 10 DEG to + 80 DEG C. The novel products are stated to be those wherein R represents an unsubstituted C3- 20 aliphatic hydrocarbon radical which may be unsaturated; an aliphatic C2- 20 hydrocarbon radical containing at least one substituent, e.g. halogen, C1- 20 alkoxy or cyanide, which radical may be unsaturated; a cycloaliphatic hydrocarbon radical with 5, 6 or 12 ring carbon atoms, optionally substituted by one or more C1- 12 alkyl radicals; an araliphatic hydrocarbon radical, optionally substituted by e.g. nitro, halogen, C1- 8 alkoxy or cyanide; an aromatic hydrocarbon radical optionally substituted by e.g. C1- 12 alkyl, C1- 8 alkoxy, halogen, nitro, cyanide or a C1- 4 carbalkoxy group, in which two such aromatic radicals may be directly connected by a C-C bond or by an oxygen or sulphur atom or a sulphone group; or a 5-membered or 6-membered heterocyclic radical containing one or two oxygen atoms as hetero atoms, which may be substituted by C1- 4 alkyl. The products are useful as plant protection agents or as wood preservatives.