Method for preparing 3,4-dimethoxytoluene by using monobromomethane-containing waste gas as raw material

Abstract

The invention provides a method for preparing 3,4-dimethoxytoluene by using monobromomethane-containing waste gas as a raw material, which comprises the following steps of: alkalifying 4-methyl guaiacol by using aqueous solution of inorganic base; and heating solution of the alkalified 4-methyl guaiacol until the temperature is between 60 and 150 DEG C, introducing the monobromomethane-containing waste gas, and after a reaction is finished, cooling reaction solution and separating directly to obtain the 3,4-dimethoxytoluene. A small amount of catalyst is added into the reaction solution, so that the reaction speed and the selectivity of a target product can be improved. The method provided by the invention can be used for recycling monobromomethane-containing industrial waste gas with high 3,4-dimethoxytoluene selectivity and yield. In addition, the method is simple and low in cost and has an excellent application prospect.

Description

Technical field

[0001] The invention relates to the fields of fine chemical industry and organic synthesis, and more specifically relates to a method for preparing 3,4-dimethoxytoluene by using waste gas containing bromomethane as a raw material.

Background technique

[0002] 3,4-Dimethoxytoluene (3,4-Dimethoxytoluene), also known as 1,2-dimethoxy-4-methylbenzene, is an important intermediate in the synthesis of perfumes and pharmaceuticals, and has a large market demand. At present, the synthesis of 3,4-dimethoxytoluene mainly has the following approaches: (1) It is obtained by decomposing complex compounds containing 3,4-dimethoxytoluene structure, wherein 3,4-dimethoxytoluene is used as a by-product product produced. Such synthesis method, the yield of 3,4-dimethoxytoluene is very low, and the product is complex, difficult to separate, and cannot efficiently produce 3,4-dimethoxytoluene. (2) The hydrogen on the 3,4-dimethoxytoluene methyl group is replaced by a halo...

Examples

Embodiment 1

[0015] Weigh 8.28g (0.06mol) of 4-methylguaiacol into a 100ml two-necked flask, add 30ml of 2M KOH solution, slowly heat up to 100°C under stirring, and introduce The industrial waste gas in the reaction until the reaction is complete, the isolated yield of 3,4-dimethoxytoluene is 96.3%.

Embodiment 2

[0017] Weigh 8.28g (0.06mol) 4-methylguaiacol in a 100ml two-necked flask, add 30ml 2M NaOH solution and 0.137g catalyst (CH 3 ) 4 In NBr, the temperature was slowly raised to 120° C. under stirring, and the industrial waste gas from the synthesis process of methyl catechol was introduced until the reaction was complete. The isolated yield of 3,4-dimethoxytoluene was 99.2%.

Embodiment 3

[0019] Weigh 8.28g (0.06mol) 4-methylguaiacol in a 100ml two-necked flask, add 30ml 2M NaOH solution and 0.30g (C 4 h 9 ) 4 In NBr, the temperature was slowly raised to 80° C. under stirring, and the industrial waste gas from the synthesis process of methyl catechol was introduced until the reaction was complete. The isolated yield of 3,4-dimethoxytoluene was 99.1%.

Technical field

[0001] The invention relates to the fields of fine chemical industry and organic synthesis, and more specifically relates to a method for preparing 3,4-dimethoxytoluene by using waste gas containing bromomethane as a raw material.

Background technique

[0002] 3,4-Dimethoxytoluene (3,4-Dimethoxytoluene), also known as 1,2-dimethoxy-4-methylbenzene, is an important intermediate in the synthesis of perfumes and pharmaceuticals, and has a large market demand. At present, the synthesis of 3,4-dimethoxytoluene mainly has the following approaches: (1) It is obtained by decomposing complex compounds containing 3,4-dimethoxytoluene structure, wherein 3,4-dimethoxytoluene is used as a by-product product produced. Such synthesis method, the yield of 3,4-dimethoxytoluene is very low, and the product is complex, difficult to separate, and cannot efficiently produce 3,4-dimethoxytoluene. (2) The hydrogen on the 3,4-dimethoxytoluene methyl group is replaced by a halo...

Examples

Embodiment 1

[0015] Weigh 8.28g (0.06mol) of 4-methylguaiacol into a 100ml two-necked flask, add 30ml of 2M KOH solution, slowly heat up to 100°C under stirring, and introduce The industrial waste gas in the reaction until the reaction is complete, the isolated yield of 3,4-dimethoxytoluene is 96.3%.

Embodiment 2

[0017] Weigh 8.28g (0.06mol) 4-methylguaiacol in a 100ml two-necked flask, add 30ml 2M NaOH solution and 0.137g catalyst (CH 3 ) 4 In NBr, the temperature was slowly raised to 120° C. under stirring, and the industrial waste gas from the synthesis process of methyl catechol was introduced until the reaction was complete. The isolated yield of 3,4-dimethoxytoluene was 99.2%.

Embodiment 3

[0019] Weigh 8.28g (0.06mol) 4-methylguaiacol in a 100ml two-necked flask, add 30ml 2M NaOH solution and 0.30g (C 4 h 9 ) 4 In NBr, the temperature was slowly raised to 80° C. under stirring, and the industrial waste gas from the synthesis process of methyl catechol was introduced until the reaction was complete. The isolated yield of 3,4-dimethoxytoluene was 99.1%.