CZ566889A3 - process for preparing acylisothiocyanates - Google Patents

Abstract

The principle of preparing the acylisothiocyanates of the formula I, wherein R represents alkyl such as methyl, ethyl, heptadecyl, alkenyl as styryl, 1-cyclohexenyl, aryl such as phenyl, 2-methylphenyl, 3- methylphenyl, 4, -nitrophenyl or heteroaryl as thienyl is in that the carboxylic acids of the general formula Π, where R is the same as in Formula I, is treated with tri (thiocyanate) phosphorous either directly at 50 to 100 ° C C or in the presence of a solvent such as benzene, toluene, chloroform, tetrahydrofuran, dioxane at 50 ° C to 50 ° C the boiling point of the solvent.

Description

BACKGROUND OF THE INVENTION

The invention relates to a process for the preparation of the acylisothiocyanates of the formula I

R-CO-NCS (I) wherein R represents alkyl such as methyl * ethyl * heptadecyl * 3 and alkenyl such as styryl * 1-cyclohexenyl * or aryl such as phenyl * 2-methylphenyl, 3-methylphenyl * 4-nitrophenyl * or heteroaryl such as thienyl.

BACKGROUND OF THE INVENTION

Acyl isothiocyanates have been prepared from acyl halides * most often from acyl chlorides by the action of alkaline rodanides * and NH ₄ SCN (Houben-Weyl: Methoden der Organischen Chemie Bd. IX * p. 878 * and Bd · £ 4 * p. * or M «0« Lozinskij * GIDerkač, PSPelkis * Ž.M.Ivanova in the book Reaction i methods isledovanija organičeskych soedinenij * Volume 22 * Khimija * Moscow 1971 * p · 184 and references therein) * or from the appropriate carboxylic acids by exposure However, which is unstable and its solution must be prepared just before use (Y.Taraura * T.Kawasaki * M.Tanio * Y.Kita: Chem · and Ind · 1978 * p · 806; 0. Burski * □ • Kieszkowski * □ • Michalski * M.Pakulski * AoSkowronska: C .Chem · Soc.Chem.Commun. 1978 * p · 940) ·

SUMMARY OF THE INVENTION

The process for the preparation of the acylisothiocyanates according to the invention is characterized in that the aralkyl acids of the general formula II

R-CO-OH (II) where R is the same as in formula I *, acts on the tri (thiocyanate) phosphorus of formula PO (NCS) g either directly at 50 ° C to 100 ° C or in the presence of a solvent such as benzene * toluene * chloroform * tetrahydrofuran, dioxane at 50 ° C to the boiling point of the solvent.

The advantage of the above process for the preparation of acylisothiocyanates over the methods used hitherto is that they can be prepared in one step directly from carboxylic acids using stable P0 (NCS) ₃ , whereby the desired products are obtained in high yield and purity.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

To freshly distilled PO (NCS) ₃ , 2.2 g (0.01 mol) was added 1.67 g (0.01 mol) of 4-nitrobenzoic acid and the reaction mixture was heated at 70 ° C for 6 h. After cooling and chromatography on silica gel in chloroform: hexane 3: 1, 1.3 g (65%) of 4-nitrobenzoylisothiocyanate having a melting point of 90-92 ° C are obtained.

Example 2 freshly distilled PO (NCS) ₃ 2.2 g (0.01 mol) was added dropwise to a solution of 1.37 g (0.01 mol) of phenylacetic acid in 5 ml of benzene and the reaction mixture was heated at 70 ° C for 7 h. . After evaporation of the benzene, the residue is chromatographed on silica gel with 3: 1 chloroform: hexane to give 1.51 g (85%) of phenylacetylisothiocyanate having a mp of 138-140 ° C / 50 mm Hg.

In an analogous manner, e.g. the following acylisothiocyanates:

Benzoyl isothiocyanate, b.p. 135-137 ° C / 2.4 kPa, 70% yield

2- Methylbenzoyl isothiocyanate, b.p. 90-92 ° C / 80 Pa, 90% yield

3- Methylbenzoyl isothiocyanate, b.p. 86-87 ° C / 80 Pa, yield 85%

4- Methoxybenzoyl isothiocyanate, b.p. 111-112 ° C / 93 Pa, yield 83% Cinamoylisothiocyanate, m.p. 41-43 ° C, yield 62% 2-Tenoylisothiocyanate, m.p. 78-80 ° C / 93 Pa, yield 77% Stearoylisothiocyanate, m.p. 180-183 ° C / 93 Pa, yield 65% 4-tert-butyl-1-cyclohexenecarbonylisothiocyanate, b.p. 100-101 ° C / / 93 Pa, 90% yield,

Industrial use

The obtained acylisothiocyanates serve as starting materials for the preparation of acylthioureas and various heterocyclic compounds with various biological effects.

Claims (1)

PATENT CLAIMS Process for preparing acylisothiocyanates of the formula I R-CO-NCS (I) wherein R represents alkyl such as methyl, ethyl, heptadecyl, alkenyl such as styryl, 1-cyclohexenyl, aryl such as phenyl, 2-methylphenyl, 2-methylphenyl, 3-methylphenyl, 4-nitrophenyl or heteroaryl such as thienyl characterized in that the carboxylic acids of the general formula II R-CO-OH (II) wherein R is the same as in Formula I is treated with tri (thiocyanate) phosphorus of the formula P0 (NCS) ₃ either directly at 50 to 100 ° C or in the presence of a solvent such as benzene, toluene, chloroform, tetrahydrofuran, dioxane at 50 ° C to the boiling point of the solvent ·