WO2003016263A1 - A process for the preparation of methacrylamide (maa) from acetoncyanohydrin - Google Patents

A process for the preparation of methacrylamide (maa) from acetoncyanohydrin Download PDF

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WO2003016263A1
WO2003016263A1 PCT/EP2002/008376 EP0208376W WO03016263A1 WO 2003016263 A1 WO2003016263 A1 WO 2003016263A1 EP 0208376 W EP0208376 W EP 0208376W WO 03016263 A1 WO03016263 A1 WO 03016263A1
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acid
ach
stage
alkyl
maa
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PCT/EP2002/008376
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French (fr)
Inventor
Dario Giudici
Massimo Luperi
Viviana Sciarillo
Sergio Giuliacci
Luca Sacchi
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Atofina
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C231/00—Preparation of carboxylic acid amides
    • C07C231/06—Preparation of carboxylic acid amides from nitriles by transformation of cyano groups into carboxamide groups

Definitions

  • the present invention relates to a process for the preparation of alkyl methacrylates wherein the alkyl comprises from 1 to 5 carbon atoms, linear or branched when possible, comprising the preparation of methacrylamide (MAA) by: (a) reaction of acetoncyanohydnn (ACH) with concentrated sulphuric acid and (b) subsequent transformation at high temperature of the obtained intermediates ' ⁇ -hydroxyisobutyramide ( -IIBA) and - hydroxyisobutyramide sulphate ( -IIBAS) to methacrylamide (MAA) , characate ⁇ zed m that the reaction between sulphuric acid and acetoncyanohydnn is carried out in the presence of alkyl- or aryl-sulphonic acids and in that it is carried out in more successive steps each comprising a stage of type (a) and a stage of type (b) , wherein in each step following the first one, in the stage of type (a
  • the reaction between ACH and concentrated sulphuric acid is usually carried out by using a molar excess of sulphuric acid from 1.3 to 1.6 with respect to the ACH so as to have a sufficiently fluid reaction mass to allow the reaction progress. If a lower amount of sulphuric acid is used, the viscosity of the obtained reaction mixture results too high and it does not allow the reaction progress.
  • the problem of the present invention is to prepare MAA by reaction between concentrated sulphuric acid and ACH with subsequent transformation of the obtained intermediates, using amounts of sulphuric acid lower than those of the known processes for each unity of MAA produced.
  • reaction steps each comprising stages of type (a) and of type (b) , wherein m stage (a) of the first step an alkyl- or aryl-sulphonic acid is added and wherein in each stage of type (a) of the successive reaction steps fresh ACH s reacted with the reaction mixture coming from the stage of type (b) of the previous step.
  • the process of the invention besides the use of alkyl- or aryl-sulphonic acids includes more reaction steps, each comprising the stages of type (a) and of type (b) , wherein the reaction mixture obtained from the previous stage of type (b) is fed to stage (a1 ) of the subsequent step wherein it is reacted with a further amount of fresh acetoncyanohydnn and subsequently transformed into (b1 ) , by letting follow in sequence further stages (a2), (b2), (a3), (b3), etc..
  • the number of said successive stages (a n ) , (b n ) i.e. (a1 ) , (b1 ) , etc., depends on the fact that after said sequence of stages the proviso that at least one MAA mole for every 0.3-1 moles of used on the whole sulphuric acid, is satisfied.
  • An object of the present invention is therefore a process for the preparation of alkyl methacrylates wherein the alkyl comprises from 1 to 5 carbon atoms, linear or branched when possible, including the prepartion of methacrylamide (MAA) comprising the following steps: I) which includes the stages: (a) gradual addition of acetoncyanohyd ⁇ ne (ACH) to a mixture of sulphuric acid and of an alkyl- or aryl-sulphonic acid, maintained under stirring at a reaction temperature in the range 50°C-100°C, preferably 60°-90°C, wherein the H 2 S0 4 /ACH molar ratios are in the range 1:1-2:1, and wherein the alkyl- or aryl-sulphonic acid is selected from those which result liquid at said reaction temperature; (b) heating of the reaction mixture obtained in step (a) at temperatures of 120°-160°C, preferably 130°-150°C obtaining MAA m admixture with sulphuric acid and al
  • step II heating of the reaction mixture obtained m (a1 ) by operating under the same reaction conditions described m (b) , optionally after step II) at least a step
  • the final obtained reaction mixture optionally after separation of the alkyl- or aryl-sulphonic acid, can be subjected to hydrolysis or esterification with water or C-,-C 5 aliphatic alcohols to obtain alkyl methacrylates, in particular methyl methacrylate (MMA) .
  • MMA methyl methacrylate
  • the sulphuric acid used in (a) has a concentration in the range 98%- 102% and is additived with small amounts, for example 200-400 ppm, of a MAA polymerization inhibitor, such for example phenothiazme (PTZ) .
  • a MAA polymerization inhibitor such for example phenothiazme (PTZ) .
  • the alkyl- or aryl-sulphonic acid is used in (a) m admixture with the sulphuric acid m a weight ratio in the range 10:1-1:1, preferably 4:1-3:1.
  • alkyl- or aryl-sulphonic acids usable m the present invention methansulphonic acid, trifluoromethansulphonic acid (triflic acid), dodecylbenzen-sulphonic acid can for examaple be mentioned, preferably methansulphonic acid (AMS) is used.
  • AMS methansulphonic acid
  • stage I The reaction mixture obtained in stage I is cooled to 70°C and a new aliquot of 12.2 g of ACH is added thereto in 13.2 minutes. The mixture is let react at 70°C for 10 minutes, then it is heated at 140°C for 10 minutes.
  • a sample is taken and, analyzed by HPLC, it results to contain 20.32% by weight of methacrylamide (MAA) and 0.48% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 94.02%.
  • MAA methacrylamide
  • AMA methacrylic acid
  • reaction mixture obtained m stage I is cooled to 100°C and a new aliquot of 12.2 g of ACH is added thereto m 13.2 minutes.
  • the mixture is let react at 100°C for 10 minutes, then it is heated at 140°C for 30 minutes.
  • MAA methacrylamide
  • AMA methacrylic acid
  • stage I The reaction mixture obtained in stage I is cooled to 70°C and a new aliquot of 18.4 g of ACH is added thereto. The mixture is let react at 70°C for 10 minutes, then it is heated at 140°C for 30 minutes.
  • a sample is taken and, analyzed by HPLC, it results to contain 20.31% by weight of methacrylamide (MAA) and 0.63% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 94.43%.
  • MAA methacrylamide
  • AMA methacrylic acid
  • stage III The reaction mixture obtained m stage I is cooled to 70°C and a new aliquot of 12.2 g of ACH is added thereto m 13.2 minutes. The mixture is let react at 70°C for 10 minutes, then it is heated at 140°C for 10 minutes. Stage III
  • stage II The reaction mixture obtained in stage II is cooled again to 70°C and a new aliquot of 12.2 g of ACH is added thereto m 13.2 minutes. The mixture is let react at 70 °C for 10 minutes, then it is heated at 140°C for 30 minutes.
  • a sample is taken and, analyzed by HPLC, it results to contain 23.84% by weight of methacrylamide (MAA) and 0.55% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 88.87%.
  • MAA methacrylamide
  • AMA methacrylic acid
  • stage III The reaction mixture obtained in stage I is cooled to 70°C and a new aliquot of 18.4 g of ACH is added thereto. The mixture is let react at 70°C for 10 minutes, then it s heated at 140°C for 10 minutes . Stage III
  • stage II The reaction mixture obtained in stage II is cooled again to 70 °C and a new aliquot of 18.4 g of ACH is added thereto. The mixture is let react at 70°C for 10 minutes, then it is heated at 140°C for 30 minutes.
  • MAA methacrylamide
  • AMA methacrylic acid
  • reaction mixture obtained m stage I is cooled to 100°C and a new aliquot of 18.4 g of ACH is added thereto. The mixture is let react at 100°C for 10 minutes, then it is heated at 140°C for 10 minutes.
  • a sample is taken and, analyzed by HPLC, it results to contain 34.39% by weight of methacrylamide (MAA) and 0.63% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 63.51%.
  • MAA methacrylamide
  • AMA methacrylic acid
  • reaction mixture obtained m stage I is cooled to 70°C and a new aliquot of 18 ⁇ 4 g of ACH is added thereto. The mixture is let react at 70°C for 10 minutes, then it is heated at 140°C for 10 minutes .
  • stage I The reaction mixture obtained in stage I is cooled to 70°C and a new aliquot of 18.4 g of ACH is added thereto. The mixture is let react at 70°C for 10 minutes, then it is heated at 140°C for 30 minutes.
  • a sample is taken and, analyzed by HPLC, it results to contain 10.67% by weight of methacrylamide (MAA) and 0.19% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 48.99%.
  • MAA methacrylamide
  • AMA methacrylic acid
  • reaction mixture obtained m stage I is cooled to 70°C and a new aliquot of 18.4 g of ACH is added thereto. The mixture is let react at 70°C for 10 minutes, then it is heated at 82°C for 30 minutes.

Abstract

A process for the preparation of methacrylamide (MAA) wherein 0.3 to 1 mole of H2SO4 are used for mole of MAA produced, comprising step I) which includes stage (a) of reaction of the acetoncyanohydrin (ACH) with a mixture of sulphuric acid and of an alkyl- or aryl-sulphonic acid, at temperatures of 50°-100 °C, with sulphuric acid/ACH molar ratios in the range 1:1-2:1, and stage (b) of heating of the reaction mixture of stage (a) at temperatures of 120°-160 °C, and step II) including stage (a1) of reaction of fresh ACH and the mixture coming from stage (b) under the same conditions of stage (a), and stage (b1) of heating of the reaction mixture obtained in stage (a1) under the same conditions of stage (b).

Description

A PROCESS FOR THE PREPARATION OF METHACRYLAMIDE (MAA)
FROM ACETONCYANOHYDRIN
-k -k -k - -k
The present invention relates to a process for the preparation of alkyl methacrylates wherein the alkyl comprises from 1 to 5 carbon atoms, linear or branched when possible, comprising the preparation of methacrylamide (MAA) by: (a) reaction of acetoncyanohydnn (ACH) with concentrated sulphuric acid and (b) subsequent transformation at high temperature of the obtained intermediates' α-hydroxyisobutyramide ( -IIBA) and - hydroxyisobutyramide sulphate ( -IIBAS) to methacrylamide (MAA) , characateπzed m that the reaction between sulphuric acid and acetoncyanohydnn is carried out in the presence of alkyl- or aryl-sulphonic acids and in that it is carried out in more successive steps each comprising a stage of type (a) and a stage of type (b) , wherein in each step following the first one, in the stage of type (a) the reaction mixture coming from the previous stage of type (b) is used instead of the sulphuric acid.
With the process of the present invention it is possible to obtain high yields from 85% to 95%, in MAA usisng from 0.3 to 1 mole of sulphuric acid for mole of produced MAA.
The reaction between ACH and concentrated sulphuric acid is usually carried out by using a molar excess of sulphuric acid from 1.3 to 1.6 with respect to the ACH so as to have a sufficiently fluid reaction mass to allow the reaction progress. If a lower amount of sulphuric acid is used, the viscosity of the obtained reaction mixture results too high and it does not allow the reaction progress.
In the MAA production plants starting from ACH the disposal of large amounts of sulphuric acid which is necessary to use has a great importance. Such disposal implies indeed considerable additional costs for its transformation and/or recovery.
In EP 226,724 the reaction between ACH and sulphuric acid using molar ratios in the range 1.1:1-1.4:1 is described, carrying out the reaction in the presence of a C5-C7 hydrocarbon solvent, preferably hexane .
The need was therefore felt to decrease the amounts of sulphuric acid necessary to obtain a determined amount of MAA.
The problem of the present invention is to prepare MAA by reaction between concentrated sulphuric acid and ACH with subsequent transformation of the obtained intermediates, using amounts of sulphuric acid lower than those of the known processes for each unity of MAA produced.
It has been unexpectedly and surprisingly found that said object is reached by using more reaction steps each comprising stages of type (a) and of type (b) , wherein m stage (a) of the first step an alkyl- or aryl-sulphonic acid is added and wherein in each stage of type (a) of the successive reaction steps fresh ACH s reacted with the reaction mixture coming from the stage of type (b) of the previous step.
In other words the process of the invention besides the use of alkyl- or aryl-sulphonic acids includes more reaction steps, each comprising the stages of type (a) and of type (b) , wherein the reaction mixture obtained from the previous stage of type (b) is fed to stage (a1 ) of the subsequent step wherein it is reacted with a further amount of fresh acetoncyanohydnn and subsequently transformed into (b1 ) , by letting follow in sequence further stages (a2), (b2), (a3), (b3), etc.. The number of said successive stages (an) , (bn) , i.e. (a1 ) , (b1 ) , etc., depends on the fact that after said sequence of stages the proviso that at least one MAA mole for every 0.3-1 moles of used on the whole sulphuric acid, is satisfied.
An object of the present invention is therefore a process for the preparation of alkyl methacrylates wherein the alkyl comprises from 1 to 5 carbon atoms, linear or branched when possible, including the prepartion of methacrylamide (MAA) comprising the following steps: I) which includes the stages: (a) gradual addition of acetoncyanohydπne (ACH) to a mixture of sulphuric acid and of an alkyl- or aryl-sulphonic acid, maintained under stirring at a reaction temperature in the range 50°C-100°C, preferably 60°-90°C, wherein the H2S04/ACH molar ratios are in the range 1:1-2:1, and wherein the alkyl- or aryl-sulphonic acid is selected from those which result liquid at said reaction temperature; (b) heating of the reaction mixture obtained in step (a) at temperatures of 120°-160°C, preferably 130°-150°C obtaining MAA m admixture with sulphuric acid and alkyl- or aryl-sulphonic acid.
II) which includes the- stages:
(a1 ) gradual addition of fresh ACH to the mixture coming from (b) by operating under the same reaction conditions described in (a) ;
(b1 ) heating of the reaction mixture obtained m (a1 ) by operating under the same reaction conditions described m (b) , optionally after step II) at least a step
III) follows comprising the stages:
(a2) gradual addition of ACH to the reaction mixture coming from (b1 ) by operating under the same reaction conditions described m (a) ; (b2) heating of the reaction mixture obtained m (a2) by operating under the same reaction conditions described m
(b) with the proviso that the MAA obtained at the end of said steps is in such amount that its molar ratio with respect to the sulphuric acid used in stage (a) is in the range 1:0.3- 1:1.
After the various steps of the process have been carried out, the final obtained reaction mixture, optionally after separation of the alkyl- or aryl-sulphonic acid, can be subjected to hydrolysis or esterification with water or C-,-C5 aliphatic alcohols to obtain alkyl methacrylates, in particular methyl methacrylate (MMA) .
The sulphuric acid used in (a) has a concentration in the range 98%- 102% and is additived with small amounts, for example 200-400 ppm, of a MAA polymerization inhibitor, such for example phenothiazme (PTZ) . The alkyl- or aryl-sulphonic acid is used in (a) m admixture with the sulphuric acid m a weight ratio in the range 10:1-1:1, preferably 4:1-3:1.
As alkyl- or aryl-sulphonic acids usable m the present invention, methansulphonic acid, trifluoromethansulphonic acid (triflic acid), dodecylbenzen-sulphonic acid can for examaple be mentioned, preferably methansulphonic acid (AMS) is used.
Some illustrative examples but not limitative of the present invention follow. EXAMPLES EXAMPLE 1 Stage I
29.5 g of sulphuric acid 100%, wherein 61 mg of phenothiazine (-450 ppm based on the H2S04/AMS mixture) have been dissolved, are added to 98.6 g of methansulphonic acid. To the so obtained mixture, maintained at 70°C with a thermostatic bath, 24.5 g of acetoncyanohydnn (99.34%) are added in 26.6 minutes so to reach the H2S04/ACH molar ratio 1.05:1. The mixture is let react for 10 minutes, then it is heated at 140°C for 10 minutes. Stage II
The reaction mixture obtained in stage I is cooled to 70°C and a new aliquot of 12.2 g of ACH is added thereto in 13.2 minutes. The mixture is let react at 70°C for 10 minutes, then it is heated at 140°C for 10 minutes.
A sample is taken and, analyzed by HPLC, it results to contain 20.32% by weight of methacrylamide (MAA) and 0.48% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 94.02%.
For each gram of produced MAA, 0.861 g of sulphuric acid have been used, with a total molar ratio sulphuric acid/ACH equal to 0.70:1. EXAMPLE 2 Stage I
29.5 g of sulphuric acid 100%, wherein 64 mg of phenothiazine have been dissolved, are added to 98.6 g of methansulphonic acid. To the so obtained mixture, maintained at 100°C with a thermostatic bath, 24.5 g of acetoncyanohydnn (99.34%) are added in 26.6 minutes so to reach the H2SO„/ACH molar ratio 1.05:1. The mixture is let react for 10 minutes, then it is heated at 140°C for 10 minutes. Stage II
The reaction mixture obtained m stage I is cooled to 100°C and a new aliquot of 12.2 g of ACH is added thereto m 13.2 minutes. The mixture is let react at 100°C for 10 minutes, then it is heated at 140°C for 30 minutes.
A sample ιa taken and, analyzed by HPLC, it results to contain 19.51% by weight of methacrylamide (MAA) and 0.63% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 91.04%.
For each gram of produced MAA, 0.889 g of sulphuric acid have been used, with a total molar ratio sulphuric acid/ACH equal to 0.70:1. EXAMPLE 3 Stage I
29.5 g of sulphuric acid 100%, wherein 61 mg of phenothiazine have been dissolved, are added to 98.6 g of methansulphonic acid. To the so obtained mixture, maintained at 70°C with a thermostatic bath, 18.4 g of acetoncyanohydnn (99.34%) are added in 20 minutes so to reach the H2S04/ACH molar ratio 1.40:1. The mixture is let react for 10 minutes, then it is heated at 140°C for 10 minutes. Stage II
The reaction mixture obtained in stage I is cooled to 70°C and a new aliquot of 18.4 g of ACH is added thereto. The mixture is let react at 70°C for 10 minutes, then it is heated at 140°C for 30 minutes.
A sample is taken and, analyzed by HPLC, it results to contain 20.31% by weight of methacrylamide (MAA) and 0.63% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 94.43%.
For each gram of produced MAA, 0.854 g of sulphuric acid have been used, w th a total molar ratio sulphuric acid/ACH equal to 0.70:1. EXAMPLE 4 Stage I
29.5 g of sulphuric acid 100%, wherein 61 mg of phenothiazine have been dissolved, are added to 98.6 g of methansulphonic acid. To the so obtained mixture, maintained at 70°C with a thermostatic bath, 24.5 g of acetoncyanohydnn (99.34%) are added in 26.6 minutes so to reach the H2S04/ACH molar ratio 1.05:1. The mixture is let react for 10 minutes, then it is heated at 140°C for 10 minutes. Stage II
The reaction mixture obtained m stage I is cooled to 70°C and a new aliquot of 12.2 g of ACH is added thereto m 13.2 minutes. The mixture is let react at 70°C for 10 minutes, then it is heated at 140°C for 10 minutes. Stage III
The reaction mixture obtained in stage II is cooled again to 70°C and a new aliquot of 12.2 g of ACH is added thereto m 13.2 minutes. The mixture is let react at 70 °C for 10 minutes, then it is heated at 140°C for 30 minutes.
A sample is taken and, analyzed by HPLC, it results to contain 23.84% by weight of methacrylamide (MAA) and 0.55% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 88.87%.
For each gram of produced MAA, 0.683 g of sulphuric acid have been used, with a total molar ratio sulphuric acid/ACH equal to 0.527: 1. EXAMPLE 5 Stage I
29.5 g of sulphuric acid 100%, wherein 91 mg of phenothiazine have been dissolved, are added to 98.6 g of methansulphonic acid. To the so obtained mixture, maintained at 70 °C with a thermostatic bath, 18.4 g of acetoncyanohydnn (99.34%) are added in 20 minutes so to reach the H2S04/ACH molar ratio 1.40:1. The mixture is let react for 10 minutes, then it is heated at 140°C for 10 minutes. Stage II
The reaction mixture obtained in stage I is cooled to 70°C and a new aliquot of 18.4 g of ACH is added thereto. The mixture is let react at 70°C for 10 minutes, then it s heated at 140°C for 10 minutes . Stage III
The reaction mixture obtained in stage II is cooled again to 70 °C and a new aliquot of 18.4 g of ACH is added thereto. The mixture is let react at 70°C for 10 minutes, then it is heated at 140°C for 30 minutes.
A sample s taken and, analyzed by HPLC, it results to contain 26.21% by weight of methacrylamide (MAA) and 0.71% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 89.99%.
For each gram of produced MAA, 0.598 g of sulphuric acid have been used, with a total molar ratio sulphuric acid/ACH equal to 0.467 : 1. EXAMPLE 6 (comparative) Stage I
To 29.5 g of sulphuric acid 100%, wherein 61 mg of phenothiazine have been dissolved, maintained at 100°C with a thermostatic bath, 18.4 g of acetoncyanohydnn (99.34%) are added in 20 minutes so to reach the H2S04/ACH molar ratio 1.40:1. The mixture is let react for 10 minutes, then it is heated at 140°C for 10 minutes. Stage II
The reaction mixture obtained m stage I is cooled to 100°C and a new aliquot of 18.4 g of ACH is added thereto. The mixture is let react at 100°C for 10 minutes, then it is heated at 140°C for 10 minutes.
A sample is taken and, analyzed by HPLC, it results to contain 34.39% by weight of methacrylamide (MAA) and 0.63% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 63.51%.
For each gram of produced MAA, 1.271 g of sulphuric acid have been used, with a total molar ratio sulphuric acid/ACH equal to 0.70:1. EXAMPLE 7 (comparative) Stage I
To 128.1 g of methansulphonic acid, wherein 60 mg of phenothiazine have been dissolved, maintained at 70°C with a thermostatic bath, 18.4 g of acetoncyanohydnn (99.34%) are added in 20 minutes. The mixture is let react for 10 minutes, then it is heated at 140°C for 10 minutes. Stage II
The reaction mixture obtained m stage I is cooled to 70°C and a new aliquot of 18 ι 4 g of ACH is added thereto. The mixture is let react at 70°C for 10 minutes, then it is heated at 140°C for 10 minutes .
A sample is taken and, analyzed by HPLC, it results to contain 2.89% by weight of methacrylamide (MAA) and 0.6% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 13.31%. EXAMPLE 8 (comparative) Stage I
29.5 g of sulphuric acid 100%, wherein 61 mg of phenothiazine (-450 ppm based on the H2S04/TFA mixture) have been dissolved, are added to 98.6 g of tπfluoro acetic acid (TFA) . To the so obtained mixture, maintained at 70°C with a thermostatic bath, 18.4 g of acetoncyanohydnn (99.34%) are added in 20 minutes so to reach the H2S04/ACH molar ratio 1.40:1. The mixture is let react for 10 minutes, then it is heated at 140°C for 10 minutes. Stage II
The reaction mixture obtained in stage I is cooled to 70°C and a new aliquot of 18.4 g of ACH is added thereto. The mixture is let react at 70°C for 10 minutes, then it is heated at 140°C for 30 minutes.
A sample is taken and, analyzed by HPLC, it results to contain 10.67% by weight of methacrylamide (MAA) and 0.19% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 48.99%.
For each gram of produced MAA, 1.647 g of sulphuric acid have been used, with a total molar ratio sulphuric acid/ACH equal to 0.70:1. EXAMPLE 9 (comparative) Stage I
29.5 g of sulphuric acid 100%, wherein 61 mg of phenothiazine (-450 ppm based on the H2S04/hexane mixture) have been dissolved, are added to 98.6 g of hexane. To the so obtained mixture, maintained at 70°C with a thermostatic bath, 18.4 g of acetoncyanohydnn (99.34%) are added in 20 minutes so to reach the H2S04/ACH molar ratio 1.40:1; a brown precipitate is formed which adheres to the reaction vessel walls. The mixture is let react for 10 minutes, then it is heated at 70°-75°C (b.p. hexane = 69°-70°C) for 10 minutes. Stage II
The reaction mixture obtained m stage I is cooled to 70°C and a new aliquot of 18.4 g of ACH is added thereto. The mixture is let react at 70°C for 10 minutes, then it is heated at 82°C for 30 minutes.
Two phases are formed which are collected (by dissolving the precipitate in water) and separately analyzed by HPLC; on the whole the final sample results to contain 3.53% by weight of methacrylamide (MAA) and 0.15% by weight of methacrylic acid (AMA) , with a total yield with respect to the fed acetoncyanohydnn equal to 16.60%.
For each gram of produced MAA, 4.861 g of sulphuric acid have been used, with a total molar ratio sulphuric acid/ACH equal to 0.70:1.

Claims

CLAIMS A process for the preparation of alkyl methacrylates wherein the alkyl comprises from 1 to 5 carbon atoms, linear or branched when possible, including the preparation of methacrylamide (MA) comprising the following reaction steps: I) which includes the stages: (a) gradual addition of acetoncyanohydnn (ACH) to a mixture of sulphuric ac d and of an alkyl- or aryl-sulphonic acid, maintained under stirring at a reaction temperature in the range 50 °C- 100°C, preferably 60°C-90°C, wherein the H S04/ACH molar ratios are in the range 1:1-2:1, and wherein the alkyl- or aryl-sulphonic acid is selected from those which result liquid at said reaction temperature; (b) heating of the reaction mixture obtained in step (a) at temperatures of 120°-160°C, preferably 130°-150°C obtaining MAA in admixture with H2S04 and alkyl- or aryl-sulphonic acid; II) which includes the stages: (a1 ) gradual addition of fresh ACH to the mixture coming from (b) by operating under the same reaction conditions described n (a) ;
(b1 ) heating of the reaction mixture obtained in (a1 ) by operating under the same reaction conditions described in (b) , optionally to step II) at least a step III) follows comprising the stages:
(a2) gradual addition of fresh ACH to the reaction mixture coming from (b1 ) by operating under the same reaction conditions described in (a) ;
(b2) heating of the reaction mixture obtained in (a2) by operating under the same reaction conditions described in (b) , with the proviso that the MAA obtained at the end of said steps is in such amount that the molar ratio between MAA and the sulphuric acid used in (a) is in the range 1 :0.3-
1:1.
A process according to claim 1 , wherein the alkyl- or aryl-sulphonic acid is used in (a) in admixture with the sulphuric acid in a weight ratio in the range 10:1-1:1, preferably 4:1-3:1.
A process according to claims 1-2, wherein the alkyl- or aryl-sulphonic acid is selected from th group formed by methansulphonic acid, tπfluoromethansulphonic acid
(triflic acid) , dodecylbenzen-sulphonic acid, preferably methansulphonic acid (AMS) is used.
A process according to claims 1-3, wherein the alkyl in the alkylmethacrylates is -CH3.
PCT/EP2002/008376 2001-08-13 2002-07-26 A process for the preparation of methacrylamide (maa) from acetoncyanohydrin WO2003016263A1 (en)

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IT2001MI001784A ITMI20011784A1 (en) 2001-08-13 2001-08-13 METHACRYLAMIDE (MAA) PREPARATION PROCESS FROM ACETONCIANIDRINA
ITMI2001A001784 2001-08-13

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US7705160B2 (en) 2002-07-31 2010-04-27 E.I. Du Pont De Nemours And Company Method for preparing 3-halo-4,5-dihydro-1H-pyrazoles
WO2015055844A1 (en) * 2013-10-18 2015-04-23 Arkema France Hydrolysis vessel used in a process for amidification of acetone cyanohydrin
US11174215B2 (en) 2017-03-24 2021-11-16 Mitsubishi Chemical UK Limited Method of producing methyl methacrylate or methacrylic acid

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7705160B2 (en) 2002-07-31 2010-04-27 E.I. Du Pont De Nemours And Company Method for preparing 3-halo-4,5-dihydro-1H-pyrazoles
DE102006058250A1 (en) * 2006-12-08 2008-06-12 Evonik Röhm Gmbh Integrated process and apparatus for producing methacrylic acid esters from acetone and hydrocyanic acid
WO2015055844A1 (en) * 2013-10-18 2015-04-23 Arkema France Hydrolysis vessel used in a process for amidification of acetone cyanohydrin
FR3012143A1 (en) * 2013-10-18 2015-04-24 Arkema France
US10273199B2 (en) 2013-10-18 2019-04-30 Arkema France Hydrolysis vessel used in a process for amidification of acetone cyanohydrin
US11174215B2 (en) 2017-03-24 2021-11-16 Mitsubishi Chemical UK Limited Method of producing methyl methacrylate or methacrylic acid

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