DE826133C - Process for the preparation of dihydroresorcinol carbamic acid esters - Google Patents

Description

Process for the preparation of dihydroresorcinol carbamic acid esters Dihydroresorcinol carbamic acid esters of the general formula in which R1 and R2 denote hydrogen or methyl groups and R3 and R4 denote identical or different low molecular weight, saturated or unsaturated alkyl radicals, have not yet become known.

It has been found that these new compounds are distinguished by their snail-killing effectiveness. They are therefore suitable for the production of snail killers. The new compounds can be prepared in a manner known per se, e.g. B. by reacting dihydroresorcinols of the general formula or their salts, e.g. B. the alkali salts with carbamic acid derivatives of the general formula in which X is chlorine or bromine and R1, Ra, R $ and R4 have the meaning given at the beginning. The reactions can be carried out in the presence or absence of inert solvents such as benzene, acetone, dioxane, ethyl acetate and the like. When using the free dihydrorecorcinols, acid-binding agents are advantageously added.

The three dihydroresorcinols that can be used as starting substances are known. Dihydroresorcinol itself can e.g. B. be prepared by partially catalytic hydrogenation of resorcinol in the presence of basic compounds. 5, 5-Dimethyldihydroresorcinol (Dimedon) is advantageously produced by condensation of mesityl oxide with malonic ester according to Michael and subsequent saponification and decarboxylation (Vorländer and Erig, Liebigs Annalen der Chemie, Vol. 294, p. 314, [1897]) leaves 5-methyldihydroresorcinol z. B. by condensation of ethyl crotonate with ethyl acetoacetate and subsequent saponification and decarboxylation (from Schilling and Vorländer, Liebigs Annalen der Chemie,) 3d. 308, p.192, [1899]) or by partial reduction of orcin.

The carbamic acid derivatives of the general formula given above are mostly known. They can be made from secondary low molecular weight aliphatic Produce amines in very good yield by reaction with carbonic acid dihalides. The solutions obtained during their production in inert solvents can can also be used directly for reaction with the dihydroresorcinols.

As secondary low molecular weight aliphatic amines of the general formula for example: dimethylamine, diethylamine, di-n-propylamine, diallylamine, methylisopropylamine, ethylallylamine, di-n-butylamine, n-butylisobutylamine, methyl-n-butylamine, diamylamine. The following examples are intended to explain the preparation of the new compounds. Parts always mean parts by weight.

Example i 140 parts of 5,5-dimethyldihydroresorcinol are dissolved in the calculated amount of soda solution and evaporated to dryness. The inorganic salts are separated by extraction with absolute alcohol, the monosodium salt being obtained in a dry, easily pulverizable state after the solvent has been removed. The well powdered salt is suspended in 800 parts of dioxane and 135 parts of diethylcarbamic acid chloride are added dropwise to the suspension. The mixture is then heated to 90 to 100 ° for 12 hours and the sodium chloride formed is removed by suction from the still warm solution. After the solvent has been distilled off, the 5, 5-dimethyldihydroresorcinol diethyl carbamate is distilled in a high vacuum. The product has a boiling point of 131 to 134 ° at 0.3 mm pressure and forms a pale yellowish liquid. EXAMPLE 2 70 parts of 5,5-dimethyldihydroresorcinol are mixed with 500 parts of ethyl acetate, and 75 parts of dry potassium carbonate and 68 parts of diethylcarbamic acid chloride are added. The 'mixture is heated to boiling for 20 hours. Inorganic salts and possibly unreacted potassium salt of 5,5-dimethyldihydroresorcinol are suctioned off from the still warm solution and the diethyl carbamate is purified as described in Example i. EXAMPLE 3 140 parts of dimethyldihydroresorcinol and 97 parts of finely powdered potash are suspended in 38o parts of benzene, and the mixture is stirred at reflux temperature. The water that forms during the neutralization is distilled off azeotropically. After the water separation has ended, the suspension becomes No. 1 R, R $ R3 R4 Kp. ° C mm pressure i HH _CH, - C H3 12o to 123 o, 6 2 HH -CH3 -C2H5 118-i2o 0.25 3 HH - C2H5 - C2H1 122 - 124 0.25 4 HH - C H3 - C4 H9 132-133 0.25 5 HH - C4H;) - C4H9 150 o, 8 6 HH -CH2-CH = CH, -CH, -CH = CH, 142 to 144 o, 15 7 -CH, H -CH, -CH3 112-114 0.2 8 - C H3 H - C H3 - C 2 115 118 0.03 9-CHe H-C, H5-C2H5 136 0.7 1o-CH, H-C4H9-C4H, i45 to 147 0.1 fi - C H3 H - C4 He (iso) - C4 H9 (iso) 133 - 135 o, o8 12 -CH, -CH, -CH, -C2H5 113-116 0.1 13 -CH, -CH3 -CH, -C4H9 146-148 0.2 14 -CH, -CH, -C3H7 -C, H7 130 0.2 15 -CH, -CHs -C @ H9 -C, H, 155-157 0.2 16 -CHg -CH, -CH2-CH = CH2 -CH2-CH = CH2 142-144 0.1 17 - C H3 - CH, - C5 H1, - C5 Hii 165-167 0.25 cooled to 60 ° and a solution of 10 8 parts of dimethylcarbamic acid chloride in 500 parts of benzene was added all at once. The resulting suspension is refluxed for 12 hours and any water which may have formed is removed from the system by azeotropic distillation. After cooling, the reaction mixture is poured into 300 parts of water, the whole thing is shaken and the benzene layer is lifted off. The aqueous solution is shaken through with benzene and the combined solvents are washed neutral with water. The benzene is then distilled off under normal pressure, and the residue is fractionated in vacuo or high vacuum. Bp ii = 170 to 180 °; Yield about zoo parts.

In a high vacuum, the substance boils at 122 to 24 ° under 0.35 mm pressure and solidifies to a yellowish-white crystal mass with a melting point of 45 to 46 °.

According to the method described above, for. B. also make the following connections See table on the opposite page!

Claims (1)

PATENT CLAIM: Process for the preparation of dihydroresorcinol carbamic acid esters, characterized in that dihydroresorcinols of the general formula or their salts in a manner known per se with carbamic acid derivatives of the general formula, in which X is chlorine or bromine, in carbamic acid esters of the general formula converted, in which R1 and R $ are hydrogen or methyl groups and R $ and R4 are identical or different low molecular weight, saturated or unsaturated alkyl radicals.