CS214049B1 - Method of the production of o-cresol,2,6-xylenol and 2,3,6-trimethylphenol - Google Patents

Abstract

The invention relates to improvements in the production process 2,6-xylenol alkyl aphenol methanol; in the presence of alumina as a catalyst in which it is secondary the products obtain 2,3,6-trimethylphenol and o-cresol. From the initial mixture of phenol, o-cresol and anieol, preheated to 180 to 230 ° C non-volatile pitch liquid to liquid phase and the gaseous mixture is introduced into the alkylation reaction at 280 to 350 ° C and at atmospheric or elevated pressure up to 0.3 MPa ee addition of methanol to a total of up to 20 wt% of the reaction mixture the mixtures are separated by anisoles, phenol and 40 to 80% o-cresol contained returning to the reaction, and from the ee product isolate o-cresol, 2,6-xylenol and 2,3,6-trimethylphenol. The compounds are valuable intermediates for the production of polyphenylene oxide a vitamin E synthesis

Description

( ⁵⁴ ) A method for producing o-cresol, 2,6-xylenol and 2,3,6-trimethylphenol

The present invention relates to an improvement of the process for the preparation of 2,6-xylenol by alkylation of phenol methanol in the presence of alumina as a catalyst in which 2,3,6-trimethylphenol and o-cresol are obtained as by-products. From the starting mixture of phenol, o-cresol and anieol, preheated to 180-230 ° C, the non-volatile pitches are separated when the feedstock is transferred from the liquid to the feather phase and the gas mixture is subjected to an alkylation reaction at 280-350 ° C; at atmospheric pressure or increased to 0.3 MPa ee methanol addition up to 20 wt% total of anisols, phenol and 40-80 wt% of the o-cresol contained in the reaction mixture are recovered from the ee product isolates o-cresol, 2,6-xylenol and 2,3,6-trimethylphenol. The compounds are valuable intermediates for the production of polyphenylene oxide and the synthesis of vitamin E,

214 049 Int. C. 'C 07 C 39/07

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The invention relates to an improvement of the process for the preparation of 2,6-xyienol by phenol alkylalkyl with methanol, wherein 2,3,6-triethylphenol and o-cresol are obtained as by-products.

2,6-styrene is used to prepare valuable polymer, polyphenylene oxide and antioxidants)

2.3.6-trimethylphonol to oxidaol and hydrogenao provides 2,3,5-triastylhydroquinone, which is a fanolloc component of vitamin I synthesis.

The phenolic alkylation of methanol is a catalytic prooss. The active alumina as a catalyst for the phenol matyiaoe has been known for a long time and has been recognized in the production of o-cresol, e.g., according to Se. No. 8,132,352 · Aluminum oxide is active at a relatively low temperature, does not decompose methanol, and its selectivity for the alkylaoi to the ortho-position is limited, which is evident in the synthesis focus on

2.6- xylenol. In addition to o-cresol and 2,6-xylenol 1, other isomers of creeols and xylenols are already formed in the first stage of the alkylae, which in addition further alkylates and thus reduces the yield of the desired products. The simultaneous reaction of heat and the consequent temperature rise in the reactor has been the cause of the deterioration of the alkylane selectivity. The production of the phenols previously stored hot in multi-vessel containers contain non-volatile substances which cause clogging of preheating devices. its faster deaektivaoi.

There are known procedures that partially trick some of these difficulties · According to SOB 5 ·

555,608, it is recommended to carry out alkylaoi by fluid technique, DOS No. 2,612,075 recommends to carry out alkylaoi in the liquid phase. However, the implementation of these processes is the refining of complex equipment and special reactors.

An increase in the proportion of 2,6-aylsol and 2,3,6-triethylenenol while maintaining adequate selectivity and long catalyst life can be achieved by the method of producing o-cresol, 2,6-xylenol and 2,3,6-trimethylphenol by methyl phenol, o- cresol. cresol and salts thereof with methanol in the gas phase and in the presence of fixed alumina as a catalyst according to the invention, characterized in that it consists of a preheated mixture of phenol and o-crseol having a content of 50 to 90% ha. phenol, 10 to 50 µl ha · o-cresol and up to 5 µl ha · solsol, when the raw material is transferred from the liquid to the vapor phase at 180 to 220 ° C, separates the non-volatile pitches and the gaseous mixture at a temperature of 280 to 350 [deg.] C. and at a pressure of ataosfarlocam or increased to 0.3 KFa, the addition of methanol to a total amount of 20 [mu] ha, before separating from the reaction mixture aniaols, phenol and 40 to 80 [mu] ha The residual reaction product is worked up by known methods into o-cresol, 2,6-xylsol and 2,3,6-triastylsol.

As phenolic feedstock, ee will use a mixture of phenol and o-cresol containing 50-90 µl ha · phenol, 10-50 µl wt · o-cresol and anisole admixture up to 5 µt ha · In general, a temperature of 280 to 350 ° C, preferably 290 to 310 ° C is sufficient. The nonvolatile proportions of the feedstock are separated and discharged from the phenol stream before it is converted to a solid or very viscous, mole-like substance. For example, an additional cyclone adjustment at a suitable location in the tubular preheating furnace is suitable for this purpose. The non-volatile components ee remove the almo reactor in the form of a dilute solution in phenols and lead, for example, to the spraying of de-distillation columns.

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However, 1 other apparatus can be used to separate the nonvolatile phenolic euro substances as it enters the vapor phase. The second alkylaee feedstock, netenol, aa is fed to the reactor in steps of 2 [mu] l and 10 wt. Alkylae aa is carried out in a reactor and a fixed catalyst, the main component of which is alumina, at a temperature of 280 µL at 340 ° C and at atmospheric or moderately pressure increases to 0.3 MPa. The reactor is deck and the heat of reaction is removed gradually. The methanol flow is controlled by metering methanol and the inlet temperature. Water is separated from the reaction product. Furthermore, ether ethers, phenol and part of o-cresol. phenol, o-cresol and ethers are returned to the reactor inlet, oat-o-cresol and the portions boiling at higher temperature proceed to final separation. By separating the boiling fractions, ee achieves methanol savings because it does not reach another alkylaoi to Jejioh. O-cresol, 2,6-xylenol and rectification of the 2,6-xylenol residue also yield a 2,3,6-trimethylphenol concentrate from a reaction product with known procedures, for example, de-distillation under reduced pressure. The achieved purities of o-cresol and 2,6-xylenol are higher than those of the alkylable and phenol.

Example 1

A mixture containing 0.1 wt. water, 0.5 wt. % of eneols, 81 wt. % of phenol, 17.8 wt.% o-cresol and 0.6 wt. α + β-cresols and 2,6-xylenol. This mixture was preheated successively to 290-300 ° C. At a temperature of 185 to 200 ° C, 1 to 5 wt. liquid to the amount of heated snow. The cyclone withdrawal contained non-volatile proportions of phenols in an amount of 0.1 to 3% by weight. Methanol in liquid form was gradually added to the preheated phenol stream. Methanol was evaporated in the phenol stream before entering the catalyst. Prior to the first catalyst placement, 5. 3 to 5 wt. and before the third internship further methanol up to a total of 14 wt.

The temperature in the catalyst layers was maintained at 290 to 340 ° C. After cooling, the reaction water was separated, and the dewatered product was separated by distillation under reduced pressure into a distillate returning to the alkylaee and a distillation residue. The distillation residue contained o-cresol 60% by weight, 2,6-xylenol 28% by weight, 2,3,6-trimethylenenol 3% by weight. and up to 100 wt. were other methylphenols and pitch. Distillation of the residue gave 98% o-cresol, 98% 2,6-xylenol with an o-cresol content of up to 0.5% by weight. and 2,3,6-trimethylphenol concentrate. Example 2

Embodiment as in Example 1. A mixture containing 0.5 wt. anisols, 61 wt. % phenol, 38 wt. % o-creeol and 0.5 wt. nH-β-cresol and 2,6-xylenol together. The total amount of methanol added was 13% by weight. The composition of the alkylate after distilling off water, phenol and a portion of o-cresol was o-cresol 39% by weight, 2,6-xylenol 44.5% by weight, 2,3,6-trialethyphenol 5% by weight, up to 100% by weight . other methylphenols and pitch.

Claims (1)

tlisili TTiiiKtv A process for the preparation of o-cresol, 2,6-xylenol and 2,3,6-trimethylphenol by methylation of the mixture with a content of 50 to 90% by weight. % phenol, 10 to 50 wt. % o-creole and up to 5 wt. of anisole with methanol in the gas phase, and in the presence of fixed alumina and subsequent treatment of the product, characterized in that the phenol, o-cresol and anisols preheated to 180 DEG-230 DEG C. are separated by a nonvolatile transition from the liquid to the vapor phase. unlucky shares and 214 049, a gaseous mixture, devoid of non-volatile constituents, is reacted in an alkylation reaction at a temperature of 280 to 350 ° C and at atmospheric pressure or increased to 0.3 KPa with the addition of methanol to a total amount of 20% by weight; after separation of the anieols, phenol and 40 to 80 liters of o-creeol contained, which ae returned to the reaction, isolates o-creeol, 2,6-xylenol and 2,3,6-trimethylphenol;