DE1643763C3 - Process for the production of N-hydroxyphenyl carbamates or thiocarbamates - Google Patents

Description

by reaction of aminophenols of the general formula

(St.

with halocarbonic acid esters of the general formula

X C OR '

(MIl

where R ¹ denotes an aliphatic, cycloaliphatic ^ araliphatic or aromatic radical, R ² denotes a hydrogen or halogen atom, a nitro group or an aliphatic radical, Y denotes an oxygen or sulfur atom and X denotes a halogen atom, in an anhydrous medium and in the presence a basic compound, characterized in that sodium bicarbonate is used as the basic compound.

This invention relates to a process for the preparation of N-hydroxyphenyl carhamates or thiocarbamates by reacting aminophenols with halogen (thio) carbonic acid esters.

It is known that one can use N-hydroxyphenylcarbamates by reacting aminophenols with chlorocarbonic acid esters in the presence of acid-binding agents In the majority of these reactions, excess aminophenol itself becomes the acid-binding agent Means used (reports of the German Chemical Society, Volume 48, p. 1580 [1915]; Journal of the American Chemical Society, Vol. 48, p. 1681 [1926]; Bulletin de la Societe Chimique de France 1955, p. 1353; Comptes rendus, vol. 240, p. 1586 [1955]; U.S. PS 28 24 872; FR-PS 11 76 912). Half of the aminophenol used as the hydrochloride, which only after complex conversion into the free base can be implemented again. Such a cycle of a neutralizing agent is uneconomical.

The reaction between aminophenols and chlorocarbonic acid esters can also be carried out in an anhydrous medium and in the presence of tertiary amines, such as ζ. Β pyridine, to be carried out (Khim Nauka i. Pronu Volume 3, p. 683 [1958]; Journal of Organic Chemistry Volume 4, p. 207 [1939]). The disadvantage is the expensive one Regeneration of the tertiary amines.

Magnesium oxide (FR-PS 14 75 241) has also been recommended as an acid-binding agent, whereby one at the same time usiter addition of water to the organic solvent for a two-phase reaction medium ίο ensured, its intimate mixing for a sufficient Neutralizing effect is necessary The disadvantage of this aqueous process is that a part of the chlorocarbonic acid ester used is withdrawn from the actual implementation by hydrolysis, which leads to It is also known that aminophenols in an alkaline medium are very sensitive to oxidation (American Chemical Journal, Volume 15, p. 40 [1893], Monatshefte für Chemie Volume 10, p. 127 [1899]) and thus deliver strongly colored and impure reaction products.

Sodium and sodium hydroxide are known as hydrogen chloride acceptors in the production of ethyl N-methyl carbamate and ethyl N-tricarboxylate already used (Organic Synthesis, Coll. Vol. II, 1943 S> 5 278 and Vol. 24, 1944, p. 60).

It has now been found that N-hydroxyphenylcarbamates the general formula

by reacting aminophenols of the general formula

R ²

(N)

with halocarbonic acid esters of the general formula XC-OR ¹ (III)

HO

Y

wherein R ^{1 is} an aliphatic, cycloaliphatic ^ araliphatic or aromatic radical, R ^{2 is} a hydrogen or halogen atom, a nitro group or

denotes an aliphatic radical, Y represents an oxygen or sulfur atom and X represents Denotes halogen atom, advantageous in an anhydrous medium and in the presence of a basic compound obtained when the basic compound is sodium bicarbonate

carbonate begins.

The reaction can be carried out in the case of using m-aminopheriol and methyl chlorocarbonate represented by the following equation:

NH,

+ Cl-C-OCH, O HCI

NH-C-OCH ₃

Il ο

Compared to the known processes, the process of the invention provides N-hydroxyphenyl carbamates in a simpler and more economical way in better yield and purity. It was up in the Hinhlirk

the prior art surprising that side reactions, e.g. the oxidation of aminophenols in Presence of the basic compounds or the hydrolysis of the halocarbonic acid esters, nothing worth mentioning Role-play. In particular, the beneficial results were not in the cases too expect in which water is formed due to the reaction. Due to their high purity, the End substances in the reaction mixture without prior separation and purification directly for numerous syntheses, any water of reaction formed with prior separation or binding is further used become, e.g. in the reaction with isocyanates, carbamic acid chlorides or carboxylic acid chlorides Biscarbamates (FR-PS 14 75 241) or carbamate esters. The process according to the invention is carried out without the addition of water. The ones in alkaline Medium very oxidation-sensitive aminophenols are thus in the absence of water and with solid sodium bicarbonate reacted as acid scavenger with chlorocarbonic acid esters. Since this is initially still in Part of the m-aminophenol is also used as an acid scavenger in excess m-aminophenol initially withdrawn from the reaction as insoluble hydrochloride. It was in terms of publications in Organic Synthesis cannot foresee that the sodium carbonate, which is also insoluble in the reaction medium in the absence of water is able to convert the undissolved m-aminophenol! iydrochloride To release m-aminophenol again and to make it available for full conversion. It was rather it can be assumed that this is the result of the topochemical reaction between sodium carbonate and m-aminophenol hydrochloride forming sodium chloride as an insoluble crust on the sodium bicarbonate crystals separates and prevents the neutralization reaction from proceeding. The beneficial results of the method according to the invention, in particular within a reasonable period of time for economic application, are therefore surprising. It was also not to be expected that with this procedure the disruptive, Side reactions leading to severe discoloration and contamination, such as those for aqueous alkaline media Driving style are known, do not occur. The in Organic Synthesis, Coll. Vol. II (1943), p. 278 Procedure leads, which has not yet been described, to poor in the case of m-aminophenol Yields and heavily contaminated products.

Preferred aminophenols of the general formula II and corresponding preferred end products I are those in whose formulas R ₂ denotes a hydrogen, bromine or chlorine atom, a nitro group or an alkyl radical with up to 6 carbon atoms. The aminophenols can be p- or, in particular, o- or m-aminophenols, R ₂ substituting the benzene nucleus at any point. It can e.g. B. the following aminophenols are used as starting materials II:

o-, m-, p-aminophenols,

4-chloro (bromine) -2-aminophenol, 4- or

5-nitro-2-aminophenol,

4-methyl (butyl) -2-aminophenol,

2-methyl! -5-aminophenol,

S-MethyM-aminophenol.

Preferred halogen (thio) carbonic acid esters of the general formula HI and accordingly preferred End products I are those whose general formula Ri an alkyl, alkenyl, alkynyl, cycloalkyl, aralkyl or aryl radical, each with 1 to 12, in particular up to 7 carbon atoms, Y is an oxygen or sulfur atom and X is a bromine or in particular, chlorine atom denotes the reaction with a molar ratio of starting material is expedient 11 to starting material 1111: 1 to 1: 1.1 carried out It can e.g. B. the following halogenated carbonic acid esters are used as starting materials III:

Methyl, ethyl, isopropyl, isobutenyl, isobutinyl, cyclohexyl, benzyl, phenyl esters of chlorine or
Bromine (thio) carbonic acid.

The process of the invention is carried out without the addition of water. If necessary, depending on The basic compound used, water, is formed during the reaction. You can see the reaction in Continue in the presence of these forming amounts of water or keep the water in during the reaction sever or tie in any way. For example, an organic solvent can be chosen, with which the water can be circulated. You can also use the basic compound itself, z. B. Calcium hydroxide, or by adding desiccants, e.g. B. bind calcium chloride or sodium sulfate. Organic solvents which are inert under the reaction conditions are used in the reaction or their mixtures, expediently those in which the starting materials are readily soluble and with which optionally the water can be removed from the system during the reaction. So are z. B. as a solvent suitable: ketones such as diethyl ketone, methyl ethyl ketone, cyclohexanone; Esters such as acetic acid methyl, ethyl, isopropyl or amyl ester; aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, Dichlorobenzene; Chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane. The amount of solvent is generally three to ten times, preferably four to six times the amount by weight of the starting material II.

The sodium bicarbonate binds the hydrogen halide released during the reaction and can accordingly in a stoichiometric amount or in excess, ζ B. up to 1.2-fold excess over the stoichiomeiristhe amount to be applied.

The reaction is generally carried out at a temperature between ⁰ and 70 ° C., preferably between 25 and 45 ° C., without pressure or under pressure, continuously or batchwise.

The reaction can be carried out as follows: A mixture of starting materials II and III, organic Solvent, basic compound and optionally desiccant is for 2 to 9 hours at the Maintained reaction temperature, if appropriate with simultaneous removal of the water formed.

Then the end product is in the usual way, for. B. by filtering the reaction mixture and concentrating the Filtrate, separated

The compounds that can be produced by the process are pesticides and valuable starting materials for the production of pesticides

The parts mentioned in the examples are parts by weight.

example 1

In a mixture of 150 parts of benzene and 150 parts of ethyl acetate, 43.6 parts are obtained Dissolved m-aminophenol and treated with 35.3 parts of sodium bicarbonate

carbonate added 39.7 parts of methyl chlorocarbonate are left in this suspension at a temperature of 35.degree within 4 hours. The mixture is stirred for 2 hours at 35 ° C. and filtered then the inorganic salt formed. After concentrating the filtrate in vacuo, 65.5 parts are obtained (corresponds to 98% of theory) N- (m-hydroxyphenyl) carbamic acid methyl ester from m.p. 94 to 96 ° C.

Example 2 _{) 0}

Analogously to Example 1, 43.6 parts of m-aminophenol and 58 parts of chlorocarbonic acid-butyn- (1) -ol- (3) -ester are obtained 78 parts (corresponds to 95% of theory) N- (m-hydroxyphenyl) -carbamic acid-butyn- (1) -yI- (3) -ester from m.p. 91 to 92 ° C. 1 sec

Example 3

Analogously to Example 1, 43.6 parts of m-aminophenol and 52 parts of isopropyl chlorocarbonate are obtained 75 parts (corresponds to 96% of theory)

Isopropyl N-im-hydroxyphenylI-carbamic acid ester
from m.p. 73 to 75 ° C.

Example 4

Analogously to Example 1, 43.6 parts of m-aminophenol and 68 parts of benzyl chlorocarbonate are obtained 95.5 (corresponds to 98% of theory) N- (m-hydroxyphenyl) -carbamic acid benzyl ester of melting point 124.5 to 126.5 ° C.

Claims (1)

Claim: Process for the preparation of N-hydroxyphenyl carbamates Hzw. -thiocarbamates of general formula R ² - C- OR ¹