JPS61277648A - Production of deuterated acrylic acid or deuterated methacrylic acid - Google Patents

Abstract

PURPOSE:To obtain deuterated (meth)acrylic acid, rationally, in high selectivity nd yield, by exchanging the hydrogen of (meth)acrylic acid with deuterium in the presence of a catalyst consisting of a compound containing Rh, etc. CONSTITUTION:The objective compound can be produced by carrying out the deuterium exchange reaction of acrylic acid or methacrylic acid with a deuterium source such as heavy water or a mixture of heavy water and deuterium gas, if necessary in a solvent such as dimethylacetamide, using Rh or a compound containing Rh and a platinum-group metal as a catalyst supported optionally on a carrier such as activated carbon, in the presence of a polymerization inhibitor such as hydroquinone, preferably at 60-200 deg.C for 20min-100hr. The Rh-containing compound is e.g. Rh metal, sodium hexachlororhodate, rhodium chloride, etc., and the compound containing platinum-group element is e.g. metallic Pt, Ir or Pd, or the nitrate, chloride, complex compound, etc., of the above element such as potassium tetrachloroplatinate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing deuterated acrylic acid or deuterated methacrylic acid.

[Conventional technology]

Conventionally, methods for producing deuterated methacrylic acid include:
A method for producing deuterated methyl methacrylate via deuterated acetone cyanohydrin was published in the Journal Off.
It was proposed in Polymer Science Vol. 62, p. 95 (1962). In addition, a method of hydrolyzing deuterated methacrylamide, which is an intermediate product of this process, involves producing deuterated acetone cyanohydrin from deuterated acetone and hydrocyanic acid, and then treating this with sulfuric acid to produce methacrylamide sulfate. A method for producing deuterated methyl methacrylate by hydrolyzing it with heavy water is also known. However, the conventional method uses deuterated raw materials such as deuterated acetone and heavy water and requires many reaction steps, so it cannot be said to be economically sufficient, and an improved method with fewer steps is desired. was.

[Failure to solve the problem]

As a result of intensive research into a rational production method for deuterated methacrylic acid, the present inventors discovered a new production method for exchanging hydrogen in methacrylic acid with deuterium, and completed the present invention.

The present invention relates to the production of deuterated acrylic acid or deuterated methacrylic acid, which is characterized in that hydrogen in acrylic acid or methacrylic acid is exchanged with deuterium using rhodium or a compound containing rhodium and a platinum group element as a catalyst. It's a method.

As a deuterium source for deuterium exchange of hydrogen in acrylic acid or methacrylic acid, heavy water or a mixture of heavy water and deuterium gas can be used. It is necessary that at least a stoichiometric amount of deuterium exists in the reaction system relative to acrylic acid or methacrylic acid.

Compounds containing rhodium used as catalysts include:
Examples include rhodium itself, hexachloro, sodium diate, chlorotris (triphenylphosphine)/rhodium, and rhodium chloride.

Compounds containing platinum group elements include platinum, iridium, palladium itself, and their nitrates, chlorides, and complex compounds, such as hexachloroiridic acid,
Preferred are tetrakis(triphenylphosphine)palladium, potassium bromideplatinate, palladium nitrate, potassium hexahydroxoplatinate, potassium tetrachloroplatinate, and the like.

These compounds can also be used by being supported on a suitable carrier such as alumina, silica, silica-alumina, diatomaceous earth, or activated carbon, if necessary.

The reaction may be carried out in either gas phase or liquid phase, and can also be carried out under pressure. In order to suppress the polymerization reaction, a suitable polymerization inhibitor such as phenothiazine, hydroquinone, etc. can be added as necessary. Moreover, polymerization can also be suppressed by allowing a small amount of oxygen to coexist in the reaction solution.

In carrying out the present invention, acrylic acid or methacrylic acid is reacted with a deuterium source, such as heavy water, to exchange hydrogen from the acrylic acid or methacrylic acid with deuterium.

This reaction is carried out, if necessary, in the presence of a solvent stable at the reaction temperature, such as dimethylbucetamide, dimethylformamide, or the like. This reaction is carried out at room temperature to 300°C, but from the viewpoint of reaction rate, side reactions and inhibition of polymerization,
Preferably, the temperature is 00°C. The reaction time is usually 20 minutes to 100 hours.

Parts in the following examples mean parts by weight. Analysis was performed using a gas chromatograph and a mass spectrometer. Deuteration rate and conversion rate are defined as follows.

Reacted acrylic acid or methane Example 1 8.6 parts of methacrylic acid, 40 parts of heavy water, 2 parts of a catalyst with 1% each of palladium and rhodium supported on activated carbon powder, and a small amount of hydroquinone as a polymerization inhibitor were placed in a small autoclave and stirred. The mixture was reacted at a reaction temperature of 110° C. for 16 hours. After cooling, the reaction product was analyzed, and it was found that deuterated methacrylic acid with a conversion rate of 85% and a deuteration rate of 34% was obtained.

Example 2 The reaction was carried out in the same manner as in Example 1 except that 0.2 part of sodium hexachlororhodate was used as a catalyst, the reaction temperature was 100° C., and the reaction time was 24 hours. As a result, deuterated methacrylic acid with a conversion rate of 79% and a deuteration rate of 19% was obtained.

Example 3 7.2 parts of acrylic acid, 40 parts of heavy water, chlorotris ()
0.46 part of rhodium (I7 phenylphosphine) and a trace amount of hydroquinone as a polymerization inhibitor were placed in a small autoclave, and reacted with stirring at a reaction temperature of 90° C. for 24 hours. As a result, deuterated acrylic acid with a conversion rate of 58% and a deuteration rate of 13% was obtained.

Example 4 1.7 parts of methacrylic acid, 8.0 parts of heavy water, 0 rhodium chloride
．． 52 parts and a small amount of hydroquino as a polymerization inhibitor were placed in a small autoclave, and the reaction temperature was raised to 110°C while stirring.
The mixture was reacted for 1 hour. As a result, deuterated methacrylic acid with a conversion rate of 100% and a deuteration rate of 70% was obtained.

Example 5 In addition to the raw materials of Example 4, 5.2% dimethylacetamide was added.
1 part was added thereto, and the reaction was carried out in the same manner as in Example 4 for 16 hours.

As a result, deuterated methacrylic acid with a conversion rate of 100% and a deuteration rate of 84% was obtained.

Example 6 4.3 parts of methacrylic acid, 40 parts of heavy water, 0.1 part of sodium hexachlororhodate, 0.1 part of potassium tetrachloroplatinate, and a trace amount of hydroquinone as a polymerization inhibitor were placed in a small autoclave and reacted with stirring. temperature 100
The reaction was carried out at ℃ for 24 hours. As a result, deuterated methacrylic acid with a conversion rate of 100% and a deuteration rate of 65% was obtained.

Claims (1)

[Claims] A method for producing deuterated acrylic acid or deuterated methacrylic acid, which comprises exchanging hydrogen in acrylic acid or methacrylic acid with deuterium using rhodium or a compound containing rhodium and a platinum group element as a catalyst.