JPS58185551A - Manufacture of herbicidal fenmedipham - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for the preparation of a herbicidal compound known under the name of fenmedipham.

Phenmedipham is a compound of the formula. It has already been proposed to prepare this compound by reacting N-(hydroxyphenyl)-urethane with incyanate and optionally with carbaonic chloride. (France Special IPFWA No. 1.475, 241). The reaction in this case is therefore: "or these methods present difficulties insofar as each of the reactants requires specialized manufacturing operations. In particular, for producing methyl metahydroxyphenylcarbamate" Methyl chloroformate is an uneconomical reactant.

Therefore, an improved method for producing fenmedipham has been proposed (Kekenkar Abstracts, 78th Meeting, 147
614
The amine phenol is reacted with a methanolic solution of phosgene in the presence of a binding agent, such as MgO, and then reacted with a methanolic solution of phosgene in a second step. is reacted with phosgene in the presence of dimethylaniline and sodium carbonate, and then the chloro formed is reacted with the acid carbomethoxyaminophenyl in a third step with m-)luidine.

However, this method suffers from some disadvantages: in W-I I&T, a base (
In the remaining steps of this method, on the one hand, it is necessary to neutralize the hydrochloric acid formed with a base, and on the other hand, the coexistence of hydrochloric acid and water makes the medium corrosive. , which is extremely desirable from an industrial point of view.

1st work 1! The O problem is discussed, for example, in U.S. Patent No. 3.913.
No. 47O and French Patent No. 1,554,979 have proposed a solution using techniques such as those described in French Patent No. 1,554,979, in which the m-hydroxy phenyl carbamate, but it is difficult to keep the isocyanate produced from reacting with myaminophenol or by itself, resulting in oligomers and phenmedium. The purity of the fam decreases.

It is clear that there is a need to find a simple and economical way to produce enmedifam, and despite the many possibilities, no method has yet been found for this food. t. should give high purity phenmedium.

One object of the invention is to provide a method of this kind.

According to the present invention, m-amine phenol is reacted with phosgene in a solvent of the alkyl alkanoate type at low temperature, and then the reaction mixture thus obtained is reacted with methanol, and then in the same solution. The problem is that Peng-tolyl isocyanate is reacted in the presence of an organic base.

In the first reaction step, a compound of the formula is produced, which after reaction with 7° methanol, also called m-hydroxyphenylcarbanic acid chloride, converts this acid chloride to methyl m-hydroxyphenylcarbamate. This produces diphenmedipham by reaction with nl-tolyl isocyanate.

As alkyl alkane, preference is given to using alkaneminals such as methyl acetate or methyl globio/acid.

To actually carry out the reaction with phosgene tx=-aminophenol, m-aminephenol must be converted to the fI of phosgene in the alkane sapon ester therapy! It is best to add it to the liquid (without stirring).

The reaction temperature is generally -20~+40℃, preferably 1JlG.
~30°C range H.

The monomonophenol is added as a solution in an alkanoic acid ester solvent. If a C# thick solution is required, a hot solution can be used.

The concentration of phosgene changes during the reaction, but the initial concentration is generally between 1O and 6011Lt-, and at the end of the reaction, this concentration is very small and even reaches 0.0 The amounts of reactants used are The molar ratio of m-aminephenol Fi is in the range of 1-2, preferably in the range of 1.0 h to 1.4.

Rui response view Fffj Taku's ``-aminopheno-/I ground site/J/power, Kudomo 11 minutes later t4,
As for the above 1/1, this #J4 will be discontinued as #4L will be continued while stirring ΔAki Misaki in one song.
The reaction itself produces a solution of q-hydrobasecyphenylkapamic acid chloride.

If phosgene remains in the reaction medium at the end of the reaction, it is preferable to remove it, for example, by evaporation, distillation, or entrainment (with rr5) operation. □ The reaction of the gauze with methanol is carried out by adding methanol to the solution obtained in the gauze 1.

The fi of methanol used is such that the molar ratio is generally in the range of 3 to 8.

Generally, the reaction is carried out at a temperature of 2°C to 100°C (if the temperature is higher than the boiling point of the mixture, it is carried out under pressure).
0 This produces a solution of methyl m-hydroxyphenylcarbamate, and then the volatile compounds of the species are removed, for example by distillation. Compounds that can be removed include tri-hydrochloric acid, excess methanol and, if necessary, a portion of the alkanoic acid ester solvent.

In order to carry out the third or final step of the present invention, m
-Tolyl isocyanate and an organic base are added to the solution of methyl m-hydroxyphenylcarbamate in the alkanoic acid ester obtained in step K'. Other compounds may optionally be present, as explained below. The amount of m-)lylisocyanate added is advantageously
The amount is such that its molar ratio to the m-amine phenol used in the process ranges from 1 to 1.5, preferably from 1.02 to 1.2.

Typically, the reaction is carried out at 20-120°C (under pressure if necessary), preferably at 40-80°C.

Suitable organic bases are tertiary amines such as trialkylamines, including triethylamine. The base noodles used should be between 01% and 10%, but this is the proportion you should use.
-) Calculated as the number of moles relative to lylisocyanate.

After the end of the reaction, the formed phenmedifam is advantageously separated simply by cooling the mixture, which results in crystallization of high purity phenmedipham.

The mother liquor from the crystallization, containing in addition to the alkanoic acid ester solvent 7-enemedipham and excess m-)lylinocyanate and further organic 1jA groups, is reused in other operations,
A third step of the method of the invention can be carried out.

In this case, the liquor liquor of 3aI is mixed: that is, the mother ridge that has been sown is mixed with the solution of methyl m-hydroxyphenylcarbamate obtained in the second step of Ayu, and the solution of m-)lylisocyanate. be. The third step of the process according to the invention, in which no special addition of organic base is necessary in this case, is then carried out as already described. It may be necessary to distill a portion of the #I medium to crystallize the phenmedium 7am.

The yield of each reaction step in the present invention is approximately quantitative. One advantage of the process of the present invention is that the high purity of methyl m-hydroxyphenylcarbamate produced as an intermediate (according to the present invention) results in the production of highly pure 7-enemedifam.

The following examples illustrate how the invention can be practiced, but the invention is not limited thereto.

Methyl acetate (13.95 g) was introduced into a 72-meter round-bottomed vessel equipped with a stirrer under an inert atmosphere, and the methyl acetate was cooled to −20° C. Addition of 0 phosgene to liquid phosgene, which liquefies in a round bottom flask, continues until 14.01 g of it has been added (7).

m- in methyl acetate (120m) heated to 50υ
1 inophenol (1 t, eg) was then slowly added over 7 minutes, and the reaction medium IIL1& was kept at 6-8°C using a cooling pad.

The temperature was increased to 26° C. and the mixture was stirred at this temperature for 45 minutes, so that the reaction medium became clear and colorless.

Excess phosgene was removed by steaming under reduced pressure at 30°C.

Methanol (22-) was added to the mixture of carbamyl chloride in methyl acetate to give a total boiling point of N tc.
'T It was heated for about 1.5 hours (warm wrinkles: about 60℃
).

C*k (D bullet brother sex action (Hu and C mountain OH and CH
, C00C)-; CHsOH and Cl1
11 COOCHs and O azeotrope; and CHICOOC
HI) was removed by #distillation and the 1ikiF distillation was stopped when the reaction mixture reached 80°C.

Triethylamine (c+, tll
yg) and 01-) lylinocyanate (16.8 g) were added, methyl acetate (100 m) was added which resulted in the formation of a large amount of precipitate, and the mixture was boiled for 1 hour. I!j11) of about ℃.

The reaction medium thus became homogeneous. Cool it to room temperature, precipitate the 7-enmediphaam, add the mixture to F, concentrate the F solution, and evaporate the concentrate. By recovering the total S of 7-enmedifuam, 29 mg of the product was obtained, i.e., the yield was 8961.

Claims (1)

[Claims] (υ m-7-denophenol is reacted with phosgene in an alkyl alkanoate as wI medium at low temperature to form m-hydroxyphenylcarbamic acid chloride, and then 7, characterized in that the reaction solution is reacted with methanol, and then this solution is reacted with m-tolyl isocyanate in the presence of an organic base.
Method for producing Enmedi 7 Am (2) The method according to claim 1, wherein the alkanoate ester is an acetate ester or a propionate ester. (3) Reaction between phosgene and m-aminophenol 111
T car! The reaction temperature between methanol and the reaction medium is between 30 and 100°C, and / is m-) lylisocyanate and hydroxyphenyl. Claims <011, paragraphs 1 to 9, are the method described in paragraph 8, wherein the reaction temperature with methyl carpainate is 20 to 110°C. (4) The reaction temperature of phosgene and phenol is 10 to 110 Patent claim 0, wherein the reaction temperature of /l or m-tolyl isocyanate and methyl 1-hydrocIIIP diphenylcarbamate is 40 to 80°C.
mlli method according to paragraph 3 (Xu: the molar ratio of aminophenol used is between 1 and 2 for phosgene, and/or m is between 1 and 10 for methanol, and/or m) 1~ per ril incyanate
1.5, the method according to any one of claims 1 to 4. (6) The molar ratio to wI-aminophenol is from 1.05 to 1.4 for phosgene and from 1.02 to 1 for pl and/or m-tolylisocyanate at I3-8 for /l or methanol. .2 [The method according to claim E5. (7) Claims 1 to 6, wherein the organic base is a trialkylamine, preferably triethylamine.
The method described in any of the paragraphs. (6) Separate the 7 emmedium 7 am by cooling and circulate the remaining solution in a medium, provided that this medium
- The method according to any one of claims #I1 to 7] J+, which is a medium for the reaction of tolylinocyanate and methyl m-hydroxyphenylcarbaonic acid.