阅读说明：本技术 一种对甲基苯甲酸的合成方法 (A kind of synthetic method of p-methylbenzoic acid ) 是由 吴水保 于 2018-05-25 设计创作，主要内容包括：本发明公开了一种对甲基苯甲酸的合成方法,包括以下步骤：(1)取对二甲基苯置于反应釜中,加入溶剂,控制反应釜的温度为100-110℃,反应压力为0.85-0.9MPa,控制反应釜中氧气的体积分数为8-12%,再加入1,4-二氯-2,3-二氯蒽醌与N-羧基邻苯二甲酰亚胺金属催化剂,反应4-5h后停止；(2)将上述反应液降温至室温,再加入N,N-二甲基甲酰胺稀释溶解,降温至-10--15℃,结晶后的白色或浅黄色结晶粉末即为目标产物；本发明采用的催化剂的催化效果明显优于工业用金属催化剂,为对二甲苯选择性氧化合成对甲基苯甲酸的工业化生产提供了一条更为经济和环保的新途径。(The invention discloses a kind of synthetic methods of p-methylbenzoic acid, the following steps are included: (1) takes and is placed in reaction kettle to dimethyl benzene, solvent is added, the temperature for controlling reaction kettle is 100-110 DEG C, reaction pressure 0.85-0.9MPa, and the volume fraction for controlling oxygen in reaction kettle is 8-12%, add 1, chloro- 2, the 3- dichloroanthraquinone of 4- bis- and N- carboxyl phthalimide metallic catalyst stop after reacting 4-5h；(2) above-mentioned reaction solution is cooled to room temperature, adds n,N-Dimethylformamide dilution dissolution, is cooled to -10--15 DEG C, the white or Light yellow crystals powder after crystallization are target product；The catalytic effect for the catalyst that the present invention uses is substantially better than industrial gold metal catalyst, provides a new way more economical and environmentally friendly for the industrialized production of Selectivity for paraxylene oxidative synthesis p-methylbenzoic acid.)

1. a kind of synthetic method of p-methylbenzoic acid, it is characterised in that the following steps are included:

(1) it takes 20mL to be placed in reaction kettle dimethyl benzene, solvent is added, the temperature for controlling reaction kettle is 100-110 DEG C, reaction Pressure is 0.85-0.9MPa, and the volume fraction for controlling oxygen in reaction kettle is 8-12%, adds chloro- 2,3-, bis- chrloroanthracene of Isosorbide-5-Nitrae-two Quinone and N- carboxyl phthalimide metallic catalyst stop after reacting 4-5h, chloro- 2, the 3- dichloroanthraquinone of the Isosorbide-5-Nitrae-two with The additional amount of N- carboxyl phthalimide is respectively the 3-3.5% and 1-1.5% of paraxylene volume；

(2) above-mentioned reaction solution is cooled to room temperature, adds n,N-Dimethylformamide dilution dissolution, the N, N- dimethyl methyl The additional amount of amide is 8-10 times of paraxylene volume, is cooled to -10--15 DEG C, white or Light yellow crystals powder after crystallization End is target product.

2. a kind of synthetic method of p-methylbenzoic acid according to claim 1, it is characterised in that: in the step (1) Solvent be acetonitrile.

3. a kind of synthetic method of p-methylbenzoic acid according to claim 2, it is characterised in that: in the step (1) The additional amount of acetonitrile is 3-5 times of paraxylene volume.

Technical field

The present invention relates to technical field of organic synthesis, the synthetic method of specifically a kind of p-tolyl aldehyde.

Background technique

P-methylbenzoic acid is widely used as the intermediate of medicine, photosensitive material, pesticide, organic pigment.Preparation method Mainly have paraxylene or p-Methylisopropylbenzene nitric acid oxidation method, paraxylene air oxidation process, toluene carboxylated-oxidizing process, Electrosynthesis etc..In numerous synthetic routes, the paraxylene air oxidation process environmental-friendly and cheap advantage of raw material outstanding, It is allowed to most application prospect.Often using the metal ions such as cobalt as catalyst in the method for paraxylene air oxidation at present, Severe reaction conditions, or the means such as light-initiated, microwave are needed, conversion ratio and product selectivity are lower, bring one to production The problem of series.Non-metallic catalyst has comparable reactivity and higher selectivity compared with metallic catalyst, good Good environmental benefit and application prospect is just more and more to attract attention.

Therefore, for problems existing for above-mentioned synthetic method, the synthetic method for researching and developing a kind of p-methylbenzoic acid is The very urgent requirement of the industry.

Summary of the invention

The purpose of the present invention is to many deficiencies existing for the synthetic method of above-mentioned p-methylbenzoic acid, provide one kind Comprehensive cost of material is low, safety coefficient is high, the three wastes are easily processed, step is few, the synthetic method of the p-methylbenzoic acid of high income.

The present invention provides a kind of synthetic methods of p-methylbenzoic acid, comprising the following steps:

(1) it takes 20mL to be placed in reaction kettle dimethyl benzene, solvent is added, the temperature for controlling reaction kettle is 100-110 DEG C, reaction Pressure is 0.85-0.9MPa, and the volume fraction for controlling oxygen in reaction kettle is 8-12%, adds chloro- 2,3-, bis- chrloroanthracene of Isosorbide-5-Nitrae-two Quinone and N- carboxyl phthalimide metallic catalyst stop after reacting 4-5h, chloro- 2, the 3- dichloroanthraquinone of the Isosorbide-5-Nitrae-two with The additional amount of N- carboxyl phthalimide is respectively the 3-3.5% and 1-1.5% of paraxylene volume；

(2) above-mentioned reaction solution is cooled to room temperature, adds n,N-Dimethylformamide dilution dissolution, the N, N- dimethyl methyl The additional amount of amide is 8-10 times of paraxylene volume, is cooled to -10--15 DEG C, white or Light yellow crystals powder after crystallization End is target product.

Preferably, the solvent in heretofore described step (1) is acetonitrile.

Further, the additional amount of acetonitrile is 3-5 times of paraxylene volume in heretofore described step (1).

The present invention by be added the chloro- 2,3- dichloroanthraquinone of 1,4- bis- and N- carboxyl phthalimide metallic catalyst come It controls a substituent group in paraxylene and oxidation reaction generation p-methylbenzoic acid, the high conversion rate of paraxylene, to first occurs The selectivity of yl benzoic acid product is high.The chloro- 2,3- dichloroanthraquinone of 1,4- bis- and N- carboxyl phthalimide metallic catalyst Catalytic effect be substantially better than industrial gold metal catalyst, be Selectivity for paraxylene oxidative synthesis p-methylbenzoic acid industry Metaplasia production provides a new way more economical and environmentally friendly.

Specific embodiment