DE247453C - - Google Patents

Description

Of the cyanamidoformic acid esters, only the ethyl ester has been used so far, and to a certain extent awkward way in an absolutely essential solution of sodium cyanamide and chloramei ^ Senester (Bässler, Journal f. pract. Chemistry [2], 16, [1877], 143 ff.). It It has now been shown that compounds of this kind can easily be found in a pure state in general and obtained in excellent yield, if one follows the Schotten-Baumannschen method Method Haloformic acid ester combined with cyanamide in aqueous solution, whereby this can of course also be used in the form of its salts:

ROOC-Cl -f NH ₂ -CN
= ROOCN H -CN + HCl.

This course was surprising, since the cyanamido antic acid esters are very strong against alkali

are sensitive. Compared to the Bässler process, the yield is also strong '". · ■ improved, since under the experimental conditions observed no cyanamido diformic acid ester is formed.

»5 Mainly those for carrying out the reaction chloroformates used are known easy to obtain: either directly from the hydroxy compounds and phosgene (Ber. 18, 1177 et al.) Or with the help of Na-

tronlauge (Compt. rend. 128, 1579; Bull. [3],

.: '. ■■■ 21, 725 ff.) Or finally with the help of tert. Bases (patent 118537). Also the cyanamide is today in the form of its lime or. Sodium salt an easily accessible body.

The cyanamido ant acid esters behave 35 ' consistently as strong acids, the alkali salts of which are easily neutralized in water to solve. They are sometimes crystalline, mostly they put at ordinary temperature thick, colorless, non-distillable oils; their metal salts can always be in get solid form. The free cyanamido antic acid esters show the strong reactivity of the cyanamide and should therefore be used for syntheses. Regenerate with alkali they easily the hydroxyl compounds in question. By treating with water-retaining Medium they go into allophanoic acid esters.

The salts of the cyanamido antic acid esters have owing to their ready solubility and Fissile therapeutic importance.

Example I.
Ethyl cyanamidoformate.

To an aqueous solution of 84 parts of cyanamide are added, while cooling and stirring, at the same time 216 parts of chloroformic acid ester and as much sodium hydroxide solution of 20 ^° Be. flow in that the liquid always reacts weakly alkaline. After the reaction has ended, it is acidified to a strong Congo blue and extracted with ether. The ether residue is a hardly colored syrup with the properties of ethyl cyanamidoformate listed in the literature (Journ. F. Pract. Chemie 16, ^{X 53).}

Example II.
Cyanamidoformate of menthol.

331 parts of menthol chloroformate (cf. Patent 117624) are added to an alcoholic-aqueous (25 percent) solution of 70 parts of cyanamide and gradually the amount of sodium hydroxide solution of 12 ⁰ Be required for the alkaline reaction to persist, with cooling and stirring. allowed to flow. The methyl cyanamidoformate is precipitated as a colorless oil by acid. The sodium salt using sodium from the absolute ethereal solution forms fine, matted needles that are highly hygroscopic. The ■ silver salt forms microscopic needles.

Example III.
Cyanamidoformate of guaiacol.

187 parts of guaiacol chloroformate (cf. Ann. 382, 252) are mixed with so much technical calcium cyanamide liquor that than 44 parts correspond to pure cyanamide, stirred with cooling and after the disappearance of the alkaline Reaction completed the reaction by adding soda, filtered and acidified. The guaiacol cyanamidoformate forms a colorless oil. Its sodium salt, colorless mi-

microscopic needles made of alcohol ether, softened to about 80 °; the silver salt also forms microscopic ones Needles.

Example IV.

Cyanamidoformate of oxycamphor.

44 parts of cyanamide in aqueous solution and 230 parts of oxycamphor chloroformate (from oxycamphor, Ber. 30, 659, and phosgene, boiling point [5] i26 ^c ) are, as described in Examples 1 and above, with sodium hydroxide solution at 12 ° Bc. offset. After acidification, the reaction product precipitates out as a colorless oil which gradually solidifies. Flat needles made of chloroform gasoline, melting point unsharp at 112 ⁰ . , 45 sodium salt, needles made of alcohol ether, melting point air dry 141 °, steam dry 260 ° with decomposition. Silver salt colorless flakes.

Claims (1)

Patent claim: Process for the preparation of cyanamidoformic acid esters from haloformic acid esters and cyanamide or its Salts, characterized in that the reaction is carried out in the presence of alkaline agents in aqueous solution, leads. ■ · ■ · * οεηηυοκτ m the hkiciisuhuckeiiei.