Background technology Trimethylhydroquinone (TMHQ) is 2,3, and the abbreviation of 5-Trimethylhydroquinone has another name called 2,3, and the 5-Trimethyl Hydroquinone is the important intermediate of synthesising complex E (Ve), also can be used as the antioxidant of multiple material.Ve is that a kind of common drug is run foster healthcare products concurrently, has become maximum, the great VITAMIN kind of volume of production and marketing of purposes on the world market at present, and it and Vc, Va become three big pillar products of VITAMIN series together, and market outlook are wide.In VITAMIN market, the world, Ve is demand and the fastest kind of sale growth, and sales volume every year in the whole world, in whole Ve market, synthetic Ve accounted for 80% of the market share all with the speed increment of 3-5% for many years.
The synthetic Trimethylhydroquinone of industry mainly contains 1,2,4-trimethylbenzene method, Trimethylhydroquinone diethyl ester method and three kinds of technologies of three cresols methods, wherein:
1,2,4-trimethylbenzene method: 1,2, the 4-trimethylbenzene obtains 2,4 with concentrated acid sulfonation, and the 5-tri-methyl p-toluenesulfonate makes 2 through nitrated, 4,5-trimethylammonium-3,6-dinitrobenzene sulfonic acid, restore and obtain 2,3, behind the 5-trimethylammonium para-phenylene diamine dihydrochloride, generate 2,3 with the oxidation of sodium dichromate 99 sulphuric acid soln, 5-trimethylbenzoquinone (TMBQ), hydrogenating reduction obtains 2,3 then, the 5-Trimethylhydroquinone.1,2, the reaction scheme of 4-trimethylbenzene method is as follows:
This complex process, long flow path, product yield is low, uses a large amount of high strength acid and alkali, and environmental pollution is serious, and is superseded substantially.
Periodical literature " Speciality Petrochemicals progress " 2002,3 (4): 25-27 has reported hydrogen peroxide direct oxidation method Synthetic 2-3-5-Trimethylhydroquinone, it is with 1,2, the 4-trimethylbenzene is a raw material, and hydrogen peroxide-acetic acid-sulfuric acid is oxidation system, and trimethylbenzoquinone is synthesized in direct oxidation, restore the generation Trimethylhydroquinone, reaction scheme is as follows:
By petrochemical complex C
9Separate in the cut 1,2,4-trimethylbenzene source is abundant, low price for the synthetic Trimethylhydroquinone of raw material, has certain economic benefits with it, adopting hydrogen peroxide-acetic acid-sulfuric acid is oxidation system, trimethylbenzoquinone is synthesized in direct oxidation, restore the generation Trimethylhydroquinone and have characteristics such as operational path is short, equipment is simple, raw material sources are abundant, but products obtained therefrom quality and yield has much room for improvement.
Trimethylhydroquinone diethyl ester method: with reference to patent of invention ZL99100672.0 " preparation method of Trimethylhydroquinone diester and Trimethylhydroquinone ", patent of invention ZL97104282.9 " method for preparing Trimethylhydroquinone ": 4-oxygen isophorone is reset generation Trimethylhydroquinone diethyl ester, Trimethylhydroquinone second diester is in the presence of the phase blender, use diluted acid to carry out saponification, separate the Trimethylhydroquinone that forms then.The reaction scheme of Trimethylhydroquinone diethyl ester method is as follows:
This method is used a large amount of sulfuric acid in preparation Trimethylhydroquinone process, environmental pollution is big, and the three wastes are difficult; Gained Trimethylhydroquinone purity and content are lower, can't satisfy the requirement of subsequent preparation high-content vitamin V e.
Three cresols methods: China adopts the pseudocuminol method to produce Trimethylhydroquinone, with 2,3, the 6-pseudocuminol is a raw material, the chemical method Synthetic 2,3, the 5-Trimethylhydroquinone has that equipment is simple, investment is little, reaction process is easy to advantages such as control, is suitable for the production of small Trimethylhydroquinone.Chemical method generally is earlier with 2,3, the sulfonation of 6-pseudocuminol generates corresponding 4-sulfonic group-2,3, the 6-pseudocuminol, generate 2,3 through oxygenant (as Manganse Dioxide) oxidation then, the 5-trimethylbenzoquinone, after reductive agent (as vat powder) is reduced to 2,3, the 5-Trimethylhydroquinone, reaction equation is as follows:
But in actual production, 2,3, the solid 4-sulfonic group-2,3 that generates after the sulfonation of 6-pseudocuminol, 6-pseudocuminol tend to caking, with operating these blocky solid dissolvings cumbersome and time-consuming before the Manganse Dioxide oxidation.Document money east, He Houqun, Wang Kaiyi. direct oxidation method Synthetic 2-3-5-Trimethylhydroquinone [J] chemical reagent, 2002,24 (4): change sulfonation and oxidation into direct oxidation method among the 231-232, not only save this troublesome operation, also shortened technical process.Direct oxidation method synthesizes Trimethylhydroquinone, has operational path weak point, simple, the low cost and other advantages of equipment, does not especially have the preceding 4-sulfonic group-2,3 of oxidizing reaction, and the problems of dissolution of 6-pseudocuminol has excellent development utilization prospect.
2,3, the 5-trimethylbenzoquinone is 1,2, the common intermediate of 4-trimethylbenzene method and three cresols methods is with 2,3, the 5-trimethylbenzoquinone is that the method for the synthetic TMHQ of raw material mainly contains chemical reduction method and catalytic hydrogenating reduction method, and the catalytic hydrogenating reduction method has characteristics such as quality product height, cost are low, level of automation height, is the production method that at present external major company generally adopts.TMHQ produce and storage process in easy variable color, this is that TMHQ manufacturer wants to solve always and fails a major issue of fine solution.Generally believe, this is that trimethylbenzoquinone forms the quinhydrone(s) mixture with TMHQ again because TMHQ is a trimethylbenzoquinone by partial oxidation in air, and quinhydrone(s) is black when solid state, this mixture may be a molecular complex, makes TMHQ painted just because of the existence of this material.
US3723541 " MANUFACTURE OF TRIMETHYLHYDROQUINONE " discloses a kind of 2,3, the 5-trimethylbenzoquinone under catalyst action is that solvent carries out the method that catalytic hydrogenating reduction obtains Trimethylhydroquinone with the Fatty Alcohol(C12-C14 and C12-C18), but alcoholic solvent such as methyl alcohol and ethanol easily makes product TMHQ painted, influences the quality of product.
US3839468 " PROCESS FOR PRODUCING 2,3,6-TRIMETHYLHYD-ROQUINONE " discloses a kind of 2,3, and the 5-trimethylbenzoquinone under the palladium catalyst effect is that solvent carries out the method that catalytic hydrogenating reduction obtains Trimethylhydroquinone with the aliphatic ketone.
Leach catalyzer after catalytic hydrogenation is complete, add and directly to separate out crystallization after deionized water dilutes, but also have the part Trimethylhydroquinone to be detained in the solvent, so not only reduced yield but also increased the solvent recuperation difficulty.If solvent recuperation is complete, can influence the quality of product simultaneously.
Summary of the invention is in order to overcome above-mentioned the deficiencies in the prior art, the invention provides a kind ofly 2,3, and the 5-trimethylbenzoquinone is that reaction solvent carries out the method that catalytic hydrogenating reduction obtains Trimethylhydroquinone with the ethyl acetate under catalyzer 5% palladium/carbon effect.
Technical scheme of the present invention is: a kind of preparation method of high-content Trimethylhydroquinone, and described preparation method may further comprise the steps:
1) with 2,3 of 1 weight part, the ethyl acetate of 5-trimethylbenzoquinone, 2-10 weight part, the 5% palladium/carbon of 0.005-0.02 weight part are added in the hydrogenation still, feed hydrogen exchange 2-4 time;
2) start the hydrogenation still, begin to stir and heating, when temperature reaches 75-85 ℃, feed hydrogen, control reaction pressure 0.2-1.0Mpa carries out the hydro-reduction reaction;
3) reaction is basic when reaction pressure does not descend finishes, and continues insulation reaction 0.5-2h;
4) reaction finishes, and reaction solution is in 35-55 ℃ of following heat filtering;
5) ethyl acetate is reclaimed in filtrate air distillation;
When 6) reacting liquid temperature reaches 70-80 ℃, add the water of 2-10 weight part;
7) continue air distillation again to reacting liquid temperature to 90-100 ℃, to be with clean ethyl acetate;
8) be cooled to 80-90 ℃, add the vat powder of 0.01-0.06 weight part, insulated and stirred 0.5-1h;
9) be cooled to 25-35 ℃, insulated and stirred 0.5-1h;
10) filter, wash filter cake with water;
11) wet-milling to moisture≤1.0%, gets the product Trimethylhydroquinone in 45-55 ℃ of following vacuum-drying.
The invention has the beneficial effects as follows:
1) adopting ethyl acetate is the catalytic hydrogenating reduction reaction solvent, has avoided solvent to the influence that the Trimethylhydroquinone color causes, and has improved the quality of product; Consistent with the solvent that subsequent reactions adopted of preparation vitamin V e product, reduced the solvent species of whole vitamin V e product chain, more help suitability for industrialized production;
2) the method separating catalyst and the product of employing heat filtering have solved the shortcoming that Trimethylhydroquinone is easily separated out in ethyl acetate;
3) adopt air distillation to reclaim ethyl acetate, improved the rate of recovery of ethyl acetate;
4) adopt and to add before and after the water the different distillation temperature of control and distill by stages to reclaim and leach catalyzer after ethyl acetate has avoided catalytic hydrogenation fully, separate out behind the thin up directly that crystallization causes in addition the part Trimethylhydroquinone to be detained not only having reduced yield but also increased the solvent recuperation difficulty in the solvent and if solvent recuperation influences the shortcoming of quality product fully;
5) product Trimethylhydroquinone color and luster is good, content is high, good stability, be easy to store.
Preparation method of the present invention has simplified schedule of operation, has shortened the cycle, has reduced the solvent recuperation loss, has improved yield and quality product.
Embodiment the present invention is further elaborated by following examples:
Embodiment 1
In the hydrogenation still, add trimethylbenzoquinone 50g, ethyl acetate 100g, 5% palladium/carbon 0.25g feeds hydrogen exchange 2 times; Open and stir and heating, when temperature reaches 75 ℃, feed hydrogen control reaction pressure 0.2Mpa and carry out the hydro-reduction reaction; Reaction is basic when pressure does not descend finishes, and continues insulation reaction 0.5h; Reaction finishes, and reaction solution is in 35 ℃ of following heat filterings; Ethyl acetate is reclaimed in the filtrate air distillation, adds entry 150g when temperature reaches 70 ℃; Continue again air distillation to reacting liquid temperature to 90 ℃ to be with clean ethyl acetate; Be cooled to 80 ℃, powder 0.5g takes a policy; 80 ℃ of insulation 0.5h; Be cooled to 25 ℃, insulated and stirred 0.5h; Filter, water 100mL is washing leaching cake at twice; Wet-milling to moisture≤1.0%, obtains Trimethylhydroquinone 48g in 45 ℃ of following vacuum-dryings, and content is 98.9%.
Embodiment 2
In the hydrogenation still, add trimethylbenzoquinone 50g, ethyl acetate 500g, 5% palladium/carbon 1.0g feeds hydrogen exchange 4 times; Open and stir and heating, when temperature reaches 85 ℃, feed hydrogen control reaction pressure 1.0Mpa and carry out the hydro-reduction reaction; Reaction is basic when pressure does not descend finishes, and continues insulation reaction 1h; Reaction finishes, and reaction solution is in 55 ℃ of following heat filterings, and ethyl acetate is reclaimed in the filtrate air distillation, adds entry 500g when reacting liquid temperature reaches 80 ℃; Continue again air distillation to reacting liquid temperature to 100 ℃ to be with clean ethyl acetate; Be cooled to 90 ℃, powder 3g takes a policy; 90 ℃ of insulation 1h; Be cooled to 35 ℃, insulated and stirred 1h; Filter, water 100mL is washing leaching cake at twice; Wet-milling to moisture≤1.0%, obtains Trimethylhydroquinone 48.5g in 55 ℃ of following vacuum-dryings, and content is 99.2%.
Embodiment 3
In the hydrogenation still, add trimethylbenzoquinone 50g, ethyl acetate 300g, 5% palladium/carbon 0.62g feeds hydrogen exchange 3 times; Open and stir and heating, when temperature reaches 80 ℃, feed hydrogen control reaction pressure 0.6Mpa and carry out the hydro-reduction reaction; Reaction is basic when pressure does not descend finishes, and continues insulation reaction 0.5h; Reaction finishes, and reaction solution is in 45 ℃ of following heat filterings, and ethyl acetate is reclaimed in the filtrate air distillation, adds entry 300g when reacting liquid temperature reaches 75 ℃; Continue again air distillation to reacting liquid temperature to 95 ℃ to be with clean ethyl acetate; Be cooled to 85 ℃, powder 1.8g takes a policy; 85 ℃ of insulation 1h; Be cooled to 30 ℃, insulated and stirred 1h; Filter, water 100mL is washing leaching cake at twice; Wet-milling to moisture≤1.0%, obtains Trimethylhydroquinone 49.5g in 50 ℃ of following vacuum-dryings, and content is 99.4%.