CN1165809A

CN1165809A - Tech. for prodn. of dimethyl oxalate

Info

Publication number: CN1165809A
Application number: CN 97109131
Authority: CN
Inventors: 梅永泉
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-06-04
Filing date: 1997-06-04
Publication date: 1997-11-26
Anticipated expiration: 2017-06-04
Also published as: CN1061031C

Abstract

A process for preparing dimethyl oxalate features use of oxalic acid and methanol as raw materials, benzene or its homologs as extratant and sulfuric acid as catalyst, and includes esterification, demixing, distillation, crystallization, filtering and washing. Its advantages are high quality of product used to prepare sulfamethoxazole as it washed by methanol, high output rate (95%) as methanol, benzene and sulfuric acid all are circulated in closed loops, low cost and no pollution except alcohol-containing waste water.

Description

The dimethyl oxalate production technique

The present invention relates to a kind of production process of chemical product, relate in particular to a kind of dimethyl oxalate production technique.

As everyone knows, sulfamethoxazole is a kind of novel sulfa drug, has characteristics such as determined curative effect, antibiotic wide spectrum, toxic side effect be little, becomes large medicine of clinical use.At present, each producer of domestic production sulfamethoxazole all is that starting raw material is produced with the oxalic acid diethyl ester, but because the oxalic acid diethyl ester cost of material is higher, makes the cost of sulfamethoxazole improve, and is unfavorable for market competition.If produce sulfamethoxazole and substitute oxalic acid diethyl ester, its cost is greatly reduced with dimethyl oxalate.But the domestic producer that does not also have the suitability for industrialized production dimethyl oxalate up to the present.

The dimethyl oxalate production technique that purpose of the present invention is invented out at above-mentioned existing issue just, this processing method is simple, and is easy to implement, yield height, gained dimethyl oxalate superior product quality.

The objective of the invention is to realize by following measure:

This dimethyl oxalate production technique is to be raw material with oxalic acid and methyl alcohol, with benzene or substituted benzene is extraction agent, with sulfuric acid is catalyzer, through esterification, static layering, the methyl alcohol washing lotion of upper strata reaction solution adding methyl alcohol or last consignment of retention is kept away the row distillation to be concentrated, the benzene alcohol azeotropic liquid that distills out is waited until the next batch reaction and is used, concentrated solution is cooled to crystallization, filter, crystalline mother solution is ready for use on the next batch esterification, and the filter cake that filters out is the xln methanol wash, the methyl alcohol washing lotion is waited until next batch distillation usefulness, is dimethyl oxalate of the present invention after the xln drying after the washing; Isolated lower floor reaction solution adds oxalic acid and the benzene or the substituted benzene temperature raising distillation of next batch after the esterification, carry out benzene for water, discharge contains pure waste water, and crystalline mother solution and benzene alcohol distillate that remaining liq adds last consignment of carry out the next round esterification, move in circles.

In the present invention, the required temperature of esterification is 65 ℃～75 ℃, and the time is 1～6 hour; The injected volume first of required above-mentioned raw materials is: per 0.5 mole oxalic acid adds methyl alcohol 20～100ml, benzene or toluene 20～100ml, the vitriol oil 10～50ml.

One of process characteristic of the present invention is with the crystallization of methanol wash dimethyl oxalate, can satisfy the processing requirement that sulfamethoxazole is produced with the quality that guarantees dimethyl oxalate; Two of characteristics are that the methyl alcohol washing lotion with above-mentioned gained joins in the benzene extraction liquid of esterification and carries out component distillation, the condensing crystal dimethyl oxalate; Three of characteristics are to add next batch oxalic acid and benzene or toluene or substituted benzene in lower floor's layering liquid after esterification to carry out benzene and operate for water, remove water and oxalic acid crystal water that esterification produces, add benzene alcohol azeotropic liquid and the crystalline mother solution that the last consignment of reaction distillation goes out then and carry out the next batch esterification.

The invention has the advantages that: because the dimethyl oxalate methanol wash that crystallization goes out, quality better, can satisfy the processing requirement that sulfamethoxazole is produced, and methyl alcohol, oxalic acid, benzene, and sulfuric acid all carry out closed cycle, therefore yield height can reduce the cost of dimethyl oxalate, and this technological process is except containing pure waste water, discharge compliance with environmental protection requirements without any other three wastes.

The present invention does below in conjunction with embodiment and describes in further detail:

Embodiment 1

In reaction flask, add oxalic acid 63 grams (0.5 mole), methyl alcohol 50ml, benzene 50ml, the vitriol oil (90%) 10ml, backflow was carried out esterification 2 hours, standing demix, upper strata benzene liquid is poured matrass into, and the methyl alcohol washing lotion that adds last consignment of is (if produce first, then add methanol solution) concentrate, distillation, distillate is that benzene alcohol azeotropic liquid is waited until the next batch esterification, is cooled to 10 ℃ of crystallizations, filters, crystalline mother solution is ready for use on the next batch esterification, filter cake methanol wash, washing lotion are ready for use on the next batch distillation, and the gained dimethyl oxalate is product of the present invention in dry back packing.After the esterification, lower floor's mother liquor of layering gained adds next batch oxalic acid 63 grams, benzene 50ml, temperature raising distillation, carrying out benzene operates for water, after benzene is finished for water benzene steamed the crystalline mother solution and the benzene alcohol azeotropic liquid that add last consignment of again and carries out esterification, so cyclical operation, dimethyl oxalate to the oxalic acid yield more than 95%, in the whole production technology, methyl alcohol, oxalic acid, benzene, and sulfuric acid all carry out closed cycle, except containing pure waste water, discharge without any other three wastes.

Embodiment 2

In reaction flask, add oxalic acid 630 grams (0.5 mole), methyl alcohol 500ml, benzene 500ml, the vitriol oil (90%) 100ml, backflow was carried out esterification 3 hours, standing demix, upper strata benzene liquid is poured matrass into, and the methyl alcohol washing lotion that adds last consignment of is (if produce first, then add methanol solution) concentrate, distillation, distillate is that benzene alcohol azeotropic liquid is waited until the next batch esterification, is cooled to 10 ℃ of crystallizations, filters, crystalline mother solution is ready for use on the next batch esterification, filter cake methanol wash, washing lotion are ready for use on the next batch distillation, and packing is product of the present invention after the gained dimethyl oxalate drying.After the esterification, lower floor's mother liquor of layering gained adds next batch oxalic acid 630 grams, benzene 500ml, temperature raising distillation, carrying out benzene operates for water, after benzene is finished for water benzene steamed the crystalline mother solution and the benzene alcohol azeotropic liquid that add last consignment of again and carries out esterification, so cyclical operation, dimethyl oxalate to the oxalic acid yield more than 95%, in the whole production technology, methyl alcohol, oxalic acid, benzene, and sulfuric acid all carry out closed cycle, except containing pure waste water, discharge without any other three wastes.

Claims

1, a kind of dimethyl oxalate production technique, it is characterized in that: it is to be raw material with oxalic acid and methyl alcohol, with benzene or substituted benzene is extraction agent, with sulfuric acid is catalyzer, through esterification, static layering, the methyl alcohol washing lotion that the upper strata reaction solution is added methyl alcohol or last consignment of retention is distilled concentrated, azeotrope benzene alcohol distillate is told and is waited until next batch reaction usefulness, concentrated solution is cooled to crystallization, after filtration, crystalline mother solution is ready for use on the next batch esterification, the filter cake that filters out is the xln methanol wash, and the methyl alcohol washing lotion is waited until next batch distillation usefulness, is dimethyl oxalate of the present invention after the xln drying after the washing; Isolated lower floor reaction solution adds oxalic acid and benzene or substituted benzene temperature raising distillation after the esterification, carries out benzene for water, discharges to contain pure waste water, and crystalline mother solution and benzene alcohol distillate that remaining liq adds last consignment of carry out the next round esterification, move in circles.

2, dimethyl oxalate production technique according to claim 1 is characterized in that: the required excessive degree of esterification is 65 ℃～75 ℃, and the time is 1～6 hour.

3, dimethyl oxalate production technique according to claim 1 is characterized in that: the injected volume first of above-mentioned raw materials is: per 0.5 mole oxalic acid adds methyl alcohol 20～100ml, benzene or toluene 20～100ml, the vitriol oil 10～50ml.