DE2325041A1 - PROCESS FOR THE PRODUCTION OF ALKYLARYLTHIOURA AND ALKYLAMINOBENZOTHIAZOLS FOR THE PRODUCTION OF DIALKYLBENZOTHIAZOLYLURA - Google Patents

Description

BR »INGf. E ^ HÖFFMASIK · BIPI .. IKiG. W. BEETLE - BR. RER. KfAT. M. HOFFMAKM

FATE KTAirW.ä.ME ΕΜΟΟβ MÖKCKEM 8t - ARABEtIASTI FASSE * · TEA PHONE (WWl «11087

RE.S.ETABLISSEMENT (Etablissement pour Recherches Scienti- -fiques) Vaduz, Liechtenstein

Process for the preparation of alkylarylthioureas and alkylaminobenzothiazoles for Manufacture of dialkylbenzothiazolylureas

The invention relates to a process for the preparation of 1-aryl-3-alkylthioureas R ₁ NHCSNHR ₂ , where R ₁ - is an aryl _{radical and R 2 is} an alkyl radical, and in general to the preparation of organic alkylarylthiourea compounds and their use for the preparation of Alkylaminobenzothiazoles, which are known to be starting materials for the preparation of compounds such as l, 3-I>ialkyl-; 3- (2-BenzothiazGlyl) urea, and especially 1, ^ - dimethyl -} - (2-benzothiazolyl} urea.

The method according to the invention consists essentially in that you first an alkaline aryldithiocarbamate from arylamine and carbon disulfide in the presence of alkali in a gram ratio of 1: 1: 1 and then the alkaline aryldithiocarbamate in one aqueous solution on boiling with an alkylamine in one Gramole ratio of 1: 1 to 1: 5 treated.

To obtain 2-alkylaminobenzothiazole, the above is used Process with the treatment of the obtained arylalkylthlourea with sulfuryl chloride in one Gram ratio of 2: 1 - 2: 2 continued. Preferably the arylamine used is aniline, the alkylamine is methylamine and the 2-alkylaminobenzothiazole obtained is 2-methylaminobenzothiazole.

According to the invention one arrives at. Production of 1,3-dialkyl-3- (2-benzothiazole) urea, by turning the obtained 2-alkylaminobenzothiazole in the manner described above Wise can react with alkyl isocyanate.

In the following a detailed description of the invention will now be given * from which it appears that it is now is possible, l-aryl-3-alkyl urea of the type

R ₁ -NHCSNH - R ₂

to produce, where R-, an ary! radical and R _{2 is} an alkyl radical, while working in two phases «. In the first phase, an arylamine R ₁ NHp in aqueous solution is treated with carbon disulfide in the presence of an alkali or a base, whereby an alkaline aryldithiocarbamate is obtained in aqueous solution.

+ CS ₂ + NaOH ^ R ₁ NHCSSNa +

Subsequently, according to the invention, said aqueous solution of alkaline aryl dithiocarbamate is _{treated with boiling with an alkylamine R 2} NH ₂ , the alkylamine being in a stoichiometric excess, since it is volatile, whereupon the arylalkylthiourea is obtained.

R ₁ NHCSSNa + RgNH ₂ > R ₁ NHCSNHR ₂ + NaSH

One manufactured in the manner mentioned above Phenylalkylthiourea can serve according to the invention for the preparation of 2-alkylamino-benzofchlazole, in the a hydrocarbon compound with a boiling point between 70 and 15O C (for example benzene, toluene or Xylene) is treated with dissolved carbon disulfide while the temperature of the reactants is at 2o to 5o ° C, preferably 3o-40 ° C. The equation for this is.t as follows:

NHCSNHR ₂ + SO ₂ Cl _{2 ¥} 2 CNH-R ₂ + SO ₂ + 2HC1

Then the 2-alkylamino-benzothiazole with the alkyl 1-socyanate treated by 1,3-dialkyl-3- (2-benzolthiazolyourea. ■ "■ -

CN-CO-NH-R

The method described above is typical for the manufacture of 1,3r-dimethyl-3 (2 ^ benzothiazolyl) urea.

309849/1248

The examples below serve to provide a better explanation of the various aspects of the invention and are not intended to be limiting.

example 1

In a glass flask equipped with a stirrer, thermometer, dropping funnel and condenser, the mixture is at room temperature 93g (91 ecm; 1 mol) aniline, Io6g jja ^ CQ, (1 mol), 76g (65.0 ecm; iMol) carbon disulfide stirred in 600 ecm of water.

After stirring for about an hour, a slightly orange-colored solution of sodium phenyldithiocarbamate is obtained, which is added in 200 can to an aqueous solution of CHJMH ₂ (62 g, 2 mol). There is a slight rise in temperature (C50 -35 ° C.) and, with continued stirring, the mixture is brought to the boil again, whereupon this temperature is maintained for about an hour.

The mixture is then cooled while stirring, causing the oil produced in this way, namely 1-phenyl-3-ethylthiourea, to crystallize into an easily filterable white solid. 145 g of 1-phenyl-3-methyl-thiourea with a melting point of 111.5 to 112 ° C. are obtained _; after recrystallization: 112 to 113 ° C, which corresponds to a yield of 87 * 5 $ based on the aniline.

Example 2

The starting material is 1-phenyl-3-methylthiourea after drying has taken place according to the example. 1 described Method made was used, e.g. in a solution of a solvent such as toluene, and after removing water azeotropically with boiling.

3og 1-phenyl-3-methylthiourea (0.18 moles) suspended with stirring in 100 ecm toluene and 0.18

- 5 309849/1248

Mol (1 ^, 6 "ecm) SÖgCl, which is dissolved in 5ö ecm toluene, The thionyl chloride is slowly added over the course of 150 minutes with stirring.

The temperature is kept at 30 to 40 ° G, with water being cooled from the outside with "water. SO ₂ and HGi are formed in the process."

After about one hour of stirring at room temperature, the mixture is heated to the boiling point in order to drive off the entire content of HGl and SOp * A white crystalline solid (2-methylamino-benzothiazole hydrochloride) is obtained, which remains unchanged and dissolved * It is cooled and dissolved the hydrochloride with the addition of 100 to 150 ecm of water. The toluene layer is then separated and made alkaline with NaOH. _(4th

It becomes a white crystalline solid, the 2-methylaminobenzothiazole, precipitated in an amount of 25g, corresponding to a yield of 85 ^. The melting point is at 135 ° C, (after reprecipitation at 138 to 139 ° C).

Example 3

2-methylaminobenzothiazole, which using "the in The method described in Examples 1 and 2 is used as the starting material after making it has dried, for example by dissolving in a solvent like toluene and by azeotropic removal of water while boiling «'

To 15g of 2-methylaminobenzothiazole (Ö, 0914 mol) in loo ecm of toluene are now 5> 2g (6 ecm, 0.092 mol) of methyl isocyanate added, which is diluted in 30 ecm benzene.

- 6 - 309849/1248

An exothermic reaction takes place, during which the temperature is allowed to rise and, after the isocyanate has been added, the mixture is heated, whereupon a complete solution is obtained , * 5-Dimethyl l, 3- (2-benzothiazolyl) urea with a melting point of 119-12O ⁰ C, while the yield is $ 75. This yield can only be determined by the solubility of the substance in benzene. When using the mother liquor from the crystallization process for a further manufacturing process or by drying, a yield of nearly is found. .

309849/1248

Claims (2)

P a t e η t a η s ρ r Ü ο- h e 1. A process for the preparation of l-aryl-3 · - alkyl-thioureas R ₁ IJHCSNHR ₂ , where R _{1 is} an aryl radical and R _? is an alkyl radical, characterized t labeled in ze ichne that firstly an alkaline Aryldithioearbarnat from Arylaniin and carbon disulfide in the presence of alkali in a Gr anunol ratio of 1: preparing 1, and then the alkaline Aryldithiocarbamat in an aqueous solution at the boil with an alkylamine in: 1 a gram mole ratio of 1: 1 to 1: J. 2. "The method according to claim 1, characterized in that aniline is used as the arylamine, and the arylalkylthiourea obtained is 1-phenyl-3-alkylthiourea. J. Process according to Claims 1 and 2, characterized in that aniline is used as the arylamine and methylamine is used as the alkylamine, the af-ylallcyltilourea produced being 1-phenyl-3-methylthiourea. '. > 3Ό9849 / 1Μ8 "λ - ' J-V-r. :, ν; . "ORK3HNAL" INSPECTED