Method for synthesizing p-tolualdehyde

Abstract

The invention relates to a method for synthesizing p-tolualdehyde. The problems of low conversion rate of toluene and low yield of p-tolualdehyde in the prior art are mainly solved in the invention. The method for synthesizing p-tolualdehyde is characterized in that toluene and CO undergo a carbonylation reaction under the catalysis of a catalyst to obtain the p-tolualdehyde, wherein the catalystcomprises an ionic liquid and a rare earth salt, and the ionic liquid is selected from ionic liquids having a structural formula shown in the description; and in the structural formula, R1 and R2 areindependently selected from C1-C4 alkyl groups, and X is at least one selected from PF6, SbF6, AlCl4, BF4, PF4, CF3COO, CF3SO3 and (CF3SO2)2N. The method well solves the technical problems, and can beused in the industrial production of p-tolualdehyde.

Description

technical field

[0001] The invention relates to a method for synthesizing p-tolualdehyde. Background technique

[0002] p-Tolualdehyde is one of the alkyl aromatic aldehydes, that is, 4-methylbenzaldehyde (p-Tolualdehyde, PTAL for short), is a colorless or light yellow transparent liquid with a gentle floral and almond aroma, which is harmful to the eyes It is irritating to the skin. P-tolualdehyde can be highly selectively oxidized to synthesize terephthalic acid, and it is also an important intermediate in organic synthesis, which is widely used in fine chemical and pharmaceutical fields.

[0003] The synthesis methods of p-tolualdehyde mainly include direct high temperature oxidation, indirect electrosynthesis and carbonylation.

[0004] The direct high-temperature oxidation method uses p-xylene as a raw material to prepare PTAL through photobromination, alkaline hydrolysis, and oxidation of hydrogen peroxide / hydrobromic acid mixture. Although the process is easy to ob...

Examples

Embodiment 1

[0042] Add 1-butyl-3-methylimidazolium hexafluoroantimonate (0.5mol, 187g) and Sc(CF 3 SO 3 ) 3 (0.5mol, 246g), the air in the kettle is first replaced with N 2 Replaced 3 times, and then replaced 3 times with CO gas; stirred at 500rpm for 1h; added 110g of toluene; replaced the air in the kettle with CO gas 3 times; Product mixture of methylbenzaldehyde.

[0043] For ease of comparison and illustration, the catalyst formula is listed in Table 1, and the conversion rate of toluene and the yield of p-tolualdehyde are listed in Table 2.

Embodiment 2

[0045] Add 1-butyl-3-methylimidazolium hexafluorophosphate (0.5mol, 142g) and Sc(CF 3 SO 3 ) 3 (0.5mol, 246g), the air in the kettle is first replaced with N 2 Replaced 3 times, then replaced 3 times with CO gas; stirred at 500rpm for 1h; added 110g of toluene; replaced the air in the kettle with CO gas; Product mixture of benzaldehyde.

[0046] For ease of comparison and illustration, the catalyst formula is listed in Table 1, and the conversion rate of toluene and the yield of p-tolualdehyde are listed in Table 2.

Embodiment 3

[0048] Add 1-butyl-3-methylimidazolium hexafluoroantimonate (0.5mol, 187g) and Ce(CF 3 SO 3 ) 3 (0.5mol, 299g); the air in the kettle is firstly used with N 2 Replaced 3 times, and then replaced 3 times with CO gas; stirred at 500rpm for 1h; added 110g of toluene; replaced the air in the kettle with CO gas 3 times; Product mixture of methylbenzaldehyde.

[0049] For ease of comparison and illustration, the catalyst formula is listed in Table 1, and the conversion rate of toluene and the yield of p-tolualdehyde are listed in Table 2.

technical field

[0001] The invention relates to a method for synthesizing p-tolualdehyde. Background technique

[0002] p-Tolualdehyde is one of the alkyl aromatic aldehydes, that is, 4-methylbenzaldehyde (p-Tolualdehyde, PTAL for short), is a colorless or light yellow transparent liquid with a gentle floral and almond aroma, which is harmful to the eyes It is irritating to the skin. P-tolualdehyde can be highly selectively oxidized to synthesize terephthalic acid, and it is also an important intermediate in organic synthesis, which is widely used in fine chemical and pharmaceutical fields.

[0003] The synthesis methods of p-tolualdehyde mainly include direct high temperature oxidation, indirect electrosynthesis and carbonylation.

[0004] The direct high-temperature oxidation method uses p-xylene as a raw material to prepare PTAL through photobromination, alkaline hydrolysis, and oxidation of hydrogen peroxide / hydrobromic acid mixture. Although the process is easy to ob...

Examples

Embodiment 1

[0042] Add 1-butyl-3-methylimidazolium hexafluoroantimonate (0.5mol, 187g) and Sc(CF 3 SO 3 ) 3 (0.5mol, 246g), the air in the kettle is first replaced with N 2 Replaced 3 times, and then replaced 3 times with CO gas; stirred at 500rpm for 1h; added 110g of toluene; replaced the air in the kettle with CO gas 3 times; Product mixture of methylbenzaldehyde.

[0043] For ease of comparison and illustration, the catalyst formula is listed in Table 1, and the conversion rate of toluene and the yield of p-tolualdehyde are listed in Table 2.

Embodiment 2

[0045] Add 1-butyl-3-methylimidazolium hexafluorophosphate (0.5mol, 142g) and Sc(CF 3 SO 3 ) 3 (0.5mol, 246g), the air in the kettle is first replaced with N 2 Replaced 3 times, then replaced 3 times with CO gas; stirred at 500rpm for 1h; added 110g of toluene; replaced the air in the kettle with CO gas; Product mixture of benzaldehyde.

[0046] For ease of comparison and illustration, the catalyst formula is listed in Table 1, and the conversion rate of toluene and the yield of p-tolualdehyde are listed in Table 2.

Embodiment 3

[0048] Add 1-butyl-3-methylimidazolium hexafluoroantimonate (0.5mol, 187g) and Ce(CF 3 SO 3 ) 3 (0.5mol, 299g); the air in the kettle is firstly used with N 2 Replaced 3 times, and then replaced 3 times with CO gas; stirred at 500rpm for 1h; added 110g of toluene; replaced the air in the kettle with CO gas 3 times; Product mixture of methylbenzaldehyde.

[0049] For ease of comparison and illustration, the catalyst formula is listed in Table 1, and the conversion rate of toluene and the yield of p-tolualdehyde are listed in Table 2.

Images