JPS6078939A - Production of methyl methacrylate - Google Patents

Abstract

PURPOSE:To produce the titled compound in high yield, by hydrating acetone cyanhydrin produced from cyanic acid and acetone, reacting the hydration product with carbon monoxide and methanol, and dehydrating formamide produced as a by-product and recycling in the form of cyanic acid to the raw material system. CONSTITUTION:Cyanic acid is made to react with acetone in the reactor 40, and the resultant acetone cyanhydrin (ACH) is hydrated in the hydration reactor 5 to produce alpha-hydroxyisobutyramide, which is extracted from the bottom of the column 7 for the separation of low-boiling component. The obtained amide is made to react with carbon monoxide and methanol in the irrigated column reactor 12, and the produced methyl alpha-hydroxyisobutyrate and formamide are separated from each other with the separation column 24. The methyl alpha-hydroxyisobutyrate obtained from the column top is dehydrated in the dehydration reaction column 26, and the obtained methyl methacrylate is taken out of the system from the line 29. The formamide obtained from the column bottom is dehydrated in the dehydration column 32, and the produced cyanic acid is recycled through the line 35 to the ACH-synthesizing system.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a process for producing methyl methacrylate via acetone cyanohydrin.

Methyl methacrylate (MMA) is produced by reacting acetone cyanohydrin (ACH), obtained by reacting blind acid with 77 tons, with methanol in the presence of concentrated sulfuric acid. However, this method produces a large amount of waste g1. Acid and U'
With the by-product of N2-based vomiting ammonium, the raw material [112
is ultimately recovered in the form of 1.1, (d.
This is a drawback of the MMA manufacturing method using the ACH method. "Unexploded tsu" is a method for producing ACH method MM A that eliminates the above drawbacks and recovers 〒j' acid in its -1:5- form and does not involve the production of ammonium sulfate.
'r' is reacted with 7 setone (υ), acetone cyanohydrin is hydrated to produce α-human poxyisobutylene amide, which is reacted with -oxidized μJ and methanol. α-Hydroxyisobutyric mononuclear methyl and formamide are produced, α-hydroxyisobutyric mononuclear methyl and formamide are separated!'FN, and α-hydroxy and r-sobutyrolytic acid α-methyl is dehydrated and [methacrylic acid As methyl,
Formamide is dehydrated to form hydrocyanic acid, which is then mixed with hyacetone (41) and recycled.

A caused by the reaction between hydrocyanic acid and acetone at misfire +11J
(: H17) Production can be carried out by generally known means. That is, using a small silkworm alkali and amines as a catalyst, hydrocyanic acid and acetone are mixed in a liquid phase under normal pressure, and the mixture is stirred and reacted while being cooled. The reaction proceeds steadily and ACH is obtained in high yield.

The subsequent water utilization reaction of ACH proceeds in the presence of a strong acid such as sulfuric acid, but in order to economically separate the acid, a metal catalyst and an alkali catalyst are used to react with water and a solvent.
Let this reaction occur.

As the metal catalyst, copper, copper oxide, nickel, manganese oxide, etc. can generally be used, and manganese oxide is particularly preferred.

In addition, the coexistence of a solvent is also effective in this respect, and hydrophilic solvents such as acetone and methanol are suitable, with acetone being particularly preferred. The reaction may be carried out in a gas phase or a liquid phase, preferably in a liquid phase. The reaction type may be either a batch type or a flow type, but one option is to use a flow reactor having a fixed catalyst bed. The reaction pressure may be normal pressure or increased pressure, and the reaction temperature is 20°C to 200°C.
It can be carried out within the range of.

It is also possible to obtain α-hydroxyisobutyric acid amide by using microbial fish bodies or by harvesting using enzymes.

The α-hydroxyinbutyric acid amide thus obtained is reacted with methanol and carbon oxide to form methyl α-hydroxydiisobutyrate.

As the monoxide used in this process, gases that often contain it can be used, but the higher the purity, the faster the reaction and the better the efficiency. As methanol, ordinary industrial methanol is sufficient. One reaction condition is that the pressure is 1O-50Okl//cm'2, preferably 60-. 400kg/crn2, good friend 50~400
℃, preferably 100 to 600℃. temperature is 50'
If lower than C, anti-Jj: ,, speed is slow, reactor)
At temperatures above Hauυ°C, side reactions such as decomposition and polymerization of carboxylic acid amides, carboxylic acid esters, and formamide occur. The molar ratio of α-hydroxyinbutyric acid amide and methanol is 1:1 to 1860, preferably 1;5-1+2
It is 0.

The catalyst used in this process is a 7-midine or tertiary amine, and the! In addition, by combining □amidine or tertiary amine with metal carbonyl, a more preferable effect can be obtained than when using 7midine or tertiary amine alone.

Specifically, the amidine includes 1,6-di7zabicyclo(5,4,0)-undecene (ADBU), 1,5-di7zabicyclo(4,3゜0)
-Nonene (DBN), and the tertiary amine is N
-Methylpyrrolidine, N-ethylpyrrolidine, 4.4'
-trimethylene, bis(N-methylpiperidine), N
-Methylpyrrolidine, N-ethylpyrrolidine, dibiveridinomethane, dibiperidinoethane, dipiperidinopouvane, N,N'-dimethylpiperazine, N,N'-diethylpiperazine, trimethylamine, triethylamine,
Tripropylamine Tributylamine, Tetramethylethylenediamine, Tetramethyltetramethylenediamine, Dimethylethylamine, Triethylenediamine, N
, N-dimethylcyclohexylamine, etc. are used.

In addition, metal carbonyls include chromium carbonyl Cr(Co)6, molybdenum carbonyl MO(C
O)6, tungsten carb = /shiW (Co)6
, manganese carbonyl MI12 (Go)□. , rhenium carbonyl Re2(CO) , iron carbo= /shiFe
CGO> 51.10 Fe2(CO) s, Fes (CO) Ruthenium carbonyl Ru s (co) 12, Osmium Caflebo W/S Os 3 (Co) 12, Cobalt carbonyl C02 (CO8, Rhodium carbonyl R114 (
CO) Iridium cafflebonyl Ir4 (Co)12
,” carbonyl N1(CO)tQd is used.

In addition, in place of metal carbonyl, corresponding metal oxides, hydroxides, sulfates, salts of metal, carbonates, which can form metal carbonyl under snow reaction conditions,
It is also possible to use formates, acetates, oxalates, naphthenates, acetylacetone salts, chelate compounds of poly(7-minocarboxylate), halides, and the like.

When using amidine or tertiary amine, the amount of catalyst used in this process is in the range of o, ooi to 1 mol per 1 mol of carboxylic acid amide, and adding more than necessary is economical ( !Since it is not a J measure and sufficient reaction ventilation cannot be obtained if the amount added is small, the preferred method is 0,00.
It is 3 to 0.5 moles.

In addition, the metal carbonyl used is carboxylic acid 7mid 1
The amount can be selected within the range of 0.0001 to 0.5 mol, preferably 0.001 to 0.2 mol. It is also effective to use a solvent during the reaction,
As a solvent, acetone, ethyl ether, methyl formate, dimethy/repho-7remamide, etc. are used in method 3 to kill.

Methyl α-human μ-xisobutyrate was dehydrated with formamide by vacuum distillation for N1 minutes, and then methyl methacrylate (MMA) was obtained.
). Although sulfuric acid can be used as a dehydrating agent, it is disadvantageous and undesirable because the amount of sulfuric acid is 11 liters. Also, acetic anhydride,
Dehydration is also possible with calcium oxide, etc., but industrially in the liquid phase water or MMA is distilled off and reacted in the presence of a catalyst, but in the gas phase the dehydration reaction is carried out by passing over a solid catalyst. It is reasonable to do so, and it is especially preferable to do so. When the gas phase is heated at a constant pressure, solids such as silica-alumina are generally used. Furthermore, the coexistence of steam or inert gas is also effective in suppressing the precipitation of carbon on the catalyst. For gas phase fixed bed reactions, a temperature of 20 [1 to 500°C] at normal pressure is appropriate.

The formamide separated from α-hydroxyisobutyromethyl by distillation is dehydrated to form r'-acid. This dehydration reaction is carried out by passing formamide over a solid catalyst at a high temperature of 200 to 800°C. Qi 1" anti↓L, and either fixed bed or fluidized bed format may be used.

Power insect media include alumina-based catalysts, iron-rich insect media,
Manganese-ζ1.4 catalyst 1 is on the way. The yield of anti-destruction is good, and the amount of acid and water is constant. Hydrocyanic acid is mixed with water, sent to the acetone cyanohydrin synthesis process, and recycled.

According to the present invention, raw hydrocyanic acid can be recovered and recycled through porumamide without producing ammonia as a by-product in the MM A Lv production process, so the industrial significance is great at 4J1.

Example The book 'fb' was conducted on the basis of the first issue.

A Cl-
1851J? /l+r and recovery line 2 or acetone s
ao, y, 'hr and water from line 6 540 g'/
Mix with br and pass through line 4 to the fixed bed manganese oxide catalyst II! is supplied to a hydration reactor 5 filled with

The reaction temperature was 60° C., and the pressure was applied so that the reaction solution amounted to 4 Ll. Water use reaction product extracted by line 6 197
0#/llr t is α-hydroxyinbutyric acid 7mide
47.6wt96, acetone 29.5Wt9t5
, water contained 18.3wt roux. This reaction product is supplied to the light boiling point v2 (column 7, and acetone and water are recovered from 351JI to form a raw material (1 system → neucle), and from the column bar, line 8 is passed through the crude α-human p-gycin 6c1 Acid amide is extracted. The bottom liquid is methanol 16U from line 9.
O#/br,#! 980 g/I+r of unreacted α-human p-xyisobutyric acid amide from 1110, 640 g/Itr of Cr (CO) as a catalyst, and 640 g/Itr of N-methylbimicin aoy/br (supplied to mixed T& type reactor 12 via Nimori 11). Pressure 2001X9/ rx2 G,
The mixture is brought into contact with nitrogen monoxide, which is carried out at a temperature of 180 °C. Contains α-droxyisoacetic acid megyl 25.9 WL';'jrs formamide 9.3 wL%, unreacted α-human xyin butyric acid amide 24,5 wL9t) lit U-methanol 52.9Wt9+5 are doing.

Reverse LL: The produced liquid passes through the line 14 and is passed through the film evaporator 15 to remove the potassium 1 medium and the high-boiling substances in the filtrate. A portion of this liquid syneresis is purged, but most of it is returned to the raw material system through line 10. On the other hand, the evaporated fraction is led to the methanol recovery column 17 via line 16, where unreacted methanol and by-product light boiling fractions are separated and recovered from the top of the column and returned to the raw material system via lines 18 and 19. . A mixture of formamide, methyl α-hydroxyisobutyrate and unreacted α-hydroxyisobutyric acid amide recovered from the bottom of the column is sent via line 20 to an α-hydroxyisobutyric acid separation column 211, where it is separated into α-hydroxyisobutyric acid amide. 9801/hr is extracted from line 22 and circulated to the raw material system. On the other hand, the top distillate is sent to the formamide separation column 24 via line 26,
Methyl α-hydroxyisoacetate is obtained from the top of the column, and formamide is obtained from the bottom of the column. Top distillate 1osoy/hrti
The .alpha.-human p-xyisobutyric dispersion methyl is sent to a dehydration reactor 26 through a line 25'1, and dehydration is carried out in the gas phase at 500 DEG C. on a bed of silica-alumina catalyst. The dehydration reaction product (consisting of methyl methacrylate and water) passes through line 27 and is separated from water in a decanter 28, and the upper layer is crude methyl methacrylate 85011/hr? : Obtained from line 29 and sent to the purification process. Water is extracted from the heel 30.

On the other hand, formamide obtained from the bottom of 24 560#/
It is led to a formamide dehydration reactor 32 through an hr-like line 31, and is subjected to a dehydration reaction in the gas phase at 550°C in the presence of an iron oxide-alumina catalyst. The reaction product is supplied to a hydrocyanic acid recovery column 341B via a line 66. HCN212g/h from the top of the tower
Water is recovered from the r-line 55 and extracted from the tower via line 36. Fresh (FJHCN 64 #/ll
r is replenished from line 67, followed by line 38, and supplied to acetone cyanohydrin synthesis reactor 40 together with 7cetone 5951//br from *A5 order and catalyst (Rikishichiisoda), and acetone cyanohydrin Lin (ACH)es1y
/hr, and this is the starting point from line 41 as Harakoma 1. Patent applicant: Kazuyoshi Nagamachi, representative of Mitsubishi Gas Chemical Co., Ltd.

Claims (1)

[Claims] Acetone cyanohydrin obtained by reacting with hydrocyanic acid for 7 setson is subjected to a hydration reaction to produce α-human p-xisobutyric acid amide, which is then reacted with -carbon oxide and methanol to produce α
- produce methyl hydroxyisobutyrate and formamide;
Methyl α-Hydroxyisobutyrate and Polmamide”l min N!, L, Methyl α-Hydroxyisobutyrate is dehydrated to give methyl methacrylate, and formamide is dehydrated to give hydrocyanic acid, which is reacted with 1% acetone and recycled. A method for producing methyl methacrylate characterized by using