DD206988A1 - PROCESS FOR O-SUBSTITUTION OF PHENOLES - Google Patents

Abstract

The invention relates to a process for the preparation of o-substituted phenols by catalytic reaction of phenols having at least one free o-position with alcohols and / or their ethers. The aim of the invention is to provide an improved economical process which yields very high yields of o-substituted phenols. According to the invention a new catalyst with high selectivity for o-substituted phenols is used. The o-substitution of phenols is carried out according to the invention in the presence of a catalyst containing iron oxide, chromium oxide, one or more oxides of the elements titanium, zirconium, silicon, germanium, tin, lead, and one or more oxides of the alkali or alkaline earth metals , lanthanum and manganese.

Description

Berlin, the 26.1 * 1982

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Process for the preparation of o-substituted phenols Applicability of the invention

The invention relates to a process for the reaction of phenol, mono- and dialkylphenols having at least one free o-position with alcohols or ethers thereof. The compounds prepared according to the invention are valuable intermediates, for example for the production of vitamin E.

Characteristic of the known technical solutions

The preparation of o-substituted phenols, z * S * of 2 _# 6 ~ 0-dimethylphenol or 2,3, .6-trimethylphenol ,. is of great industrial interest because the former phenol derivative is required for numerous applications, in particular the production of polyoxyethylene oxide, and the latter is, for example, a precursor for the production of vitamin E. Although synthetic methods are known from the patent literature, there has hitherto been no method by which o-substitution products of high selectivity can generally be obtained from phenols having free o-positions, with driving times sufficiently long for the technical operation.

According to DE-OS 21 27 083 can indeed implement phenol with ca, 99% ± ger selectivity to 2,6-dimethylphenol. However, assuming o-cresol, the selectivity is only 95 % *

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In DE-OS 19 48 607 a process is described in which o-cresol is converted in about 84% selectivity in 2,5-dimethylphenol. Conversely, obtained according to DE-OS 24 28 with o-cresol as the starting material, a selectivity of 98 %, with phenol, however, only one of 96.5 %. which drops to 92 % over the course of 150 hours. According to DE-OS 25 47 309 formed by methylation of p-cresol, the 2,4,6-trimethylphenol in 95% yield, from m-cresol, the 2,3,6-trimethylphenol in 94% yield, while DE -OS 23 29 812 from m-cresol, the 2,3,6-trimethylphenol is formed in 32% yield.

Object of the invention

The aim of the invention is to provide an improved process for the preparation of o-substituted phenols by catalytic reaction of phenols having at least one free o-position with alcohols and / or ethers, with which the o-substituted phenols can be prepared in good yield.

Explanation of the essence of the invention

The invention has for its object to find a new catalyst with high selectivity for the formation of o-substituted phenols.

According to the present invention, it has now been found that one can substitute phenols having at least one free o-position by catalytic reaction with alcohols and / or their ethers in the o-positions, by reacting phenol and / or mono- and / or dialkylphenols with methanol and or

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Dimethyl ether in a molar ratio of 1: 0 * 1 - 10 at 270 to 390 C in the gas phase with a residence time of 0.05 to 10 see. in the presence of a catalyst consisting of oxides of iron, of chromium, of silicon and of at least one oxide of an alkaline-earth metal, of lanthanum and of manganese, or in the presence of a catalyst

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Oxides of iron, chromium, one or more oxides of germanium, titanium, zirconium, tin and lead, and consists of at least one oxide of a Alkalimetaiis, alkaline earth metal, lanthanum and manganese, reacts, wherein the molar ratios of the components at 100: 0.1-10: 0.1-10: 0.01-10.

For the alkylation of phenol, mono- or dialkylphenols with alcohols and / or their ethers, the starting materials or mixtures thereof are vaporized in the usual manner and introduced in the ratio indicated in a reactor in which the catalyst z. B. The reaction can be carried out by the novel process with advantage also in the waterbed. In addition, steam can be run in with the feedstocks in such an amount that the molar ratio of phenol and / or alkyl and / or dialkylphenol to steam is about 1: 1 * 5. The reactor is in the range of 270 -, preferably 390 G ⁰ at a temperature of 300 - 380 ⁰ G operated. The reaction is generally carried out at ITormaldruck, but can also be done with advantage under increased pressure. So it has z. B. shown that when using p-substituted phenols even when using pressures up to ca * 30 bar equally good results are obtained.

The catalyst used is, for example, a mixture of iron oxide, chromium oxide, silicon oxide and alkaline earth metal oxide in which iron oxide is present in excess. The catalyst can also z. Example, consist of a mixture of iron oxide, chromium oxide, one or more oxides of germanium, titanium, sirconium, tin and'Bleis and at least one oxide of the first or second main group of the periodic system. The oxides of germanium, titanium, zirconium, barium, calcium, strontium and manganese are preferred.

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The starting materials are used in such an amount that _sets a residence time of O ₁ oil to 10 see, preferably 1 to 3.5 sec _#i _.

Excess alcohol or ether is removed by distillation from the product mixture after leaving the reactor. Then it is separated from the water phase. Unreacted starting materials are distilled off and recycled to the reactor,

The selectivity with which substitution takes place in the free o ~ positions is generally 93 to 99 % Even after a period of time of 2,000 hours, no significant decrease in the selectivity of the catalyst can be determined * A significant advantage of the method lies in the fact in that the consumption of methanol is considerably lower than in the known processes.

Working Example

For a more detailed description of the method, the following examples serve:

example 1

A mixture of o-cresol and phenol was introduced with methanol and water in a molar ratio of 1 (o-cresol and phenol) to 4 (methanol) to 2.5 (water) vapor in a heated to ca, 360 ⁰ C fixed bed reactor, the one of iron oxide, silicon oxide ,. Chromium oxide and calcium oxide dm mole ratio 100; 2: 1: 0.2 existing catalyst

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held. The starting materials were introduced at atmospheric pressure in such an amount that the residence time 3 see. scam.

The product exiting the reactor was cooled countercurrently with feed. Excess methanol was distilled off from the resulting condensate *

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From the bottom of the aqueous phase was separated. Of the 99 % of 2.6-Xylenoi existing organic phase, the small amount of o-cresol and phenol was distilled off and recycled to the reactor · The remaining in the bottom 2.6-xylenol, which still contained 0.5 % 2.4 * 6-trimethylphenol, was finely distilled in a further column. The overall yield of 2,6-xylenol, based on o-cresol and phenol was 99 % * The overhead 2.6-Zylenol had a purity of 99.9 % · After 2000 hrs, the catalyst still showed a selectivity of 98.2 % ·

Example 2

Phenol, dimethyl ether and water were reacted in a molar ratio of 1: 2, 5: 2.5 in the vapor state as described in Example 1.

After workup, 2.6-Zylenol was obtained with a selectivity of 99%,

Example 3

Phenol, methanol and water were used in a molar ratio of 1: 0.5: 2.5 in vapor form as described in Example 1, caused to react, but the reaction temperature was 340 G ⁰ and the lake at Yerweilzeit. 5

Obtained with respect to reacted phenol, o-cresol with a selectivity of 96 % and 2.6-xylenol with a selectivity of 3.6 % . Even after 2100 hours, the activity and selectivity of the catalyst were negligible, lowered.

Example 4

There were o-cresol, methanol and water in the ratio 1: 2.5: 2.5, as specified in Example 1, reacted. The catalyst contained iron oxide, titanium, chromium oxide and calcium oxide in a molar ratio of 100: 4.5: 2: 0.5.

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After workup, 2 _f 6-xylenol was obtained with a selectivity of 99.1 % ,

Example 5

There were m-cresol * methanol and water in a molar ratio 1: 5: 2.5, as described in Example 1, implemented. The catalyst contained iron oxide, silica, chromium oxide and barium oxide in a molar ratio of 100: 2: 1 Γ 0.2.

After workup, 2,3,5-trimethylphenol was obtained with a selectivity of 99.5 % .

Example 6

P-cresol, methanol and water in a molar ratio of 1: 5: 1 were used and reacted at a pressure of 20 bar in the gas phase over the catalyst described in Example 1.

After work-up, 2,4,6-trimethylphenol was obtained with a selectivity of 99 % .

Example 7

p-cresol was reacted with methanol and water in a ratio of 1: 0.5: 0.5 according to Example 1.

There was obtained 2,4-xylenol with a selectivity of 96 % and 2,4,6-trimethylphenol with a selectivity of 3 % ,

Example 8

There were o-cresol, methanol and water in the ratio 1: 2 _r 5: 2.5, as indicated in Example 1, implemented.

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The catalyst contained iron oxide, germanium oxide, chromium oxide and barium oxide in a ratio of 100: 2: 10: 1. After work-up, 2,5-xylenol was obtained with a selectivity of 99.2 % . »

Example 9

The o-cresol, methanol and water were reacted in the ratio 1: 2.5: 2.5 _# as indicated in Example 1, The catalyst contained iron oxide, tin oxide, chromium oxide and calcium oxide in a molar ratio of 100: 2: 1: 1 "

After work-up, 2,5-xylenol was obtained with a selectivity of 98.9 % . Even after 2,000 hours, the activity and selectivity of the catalyst had not changed,

Example 10

M-cresol, methanol and water were reacted in the molar ratio 1: 5: 2.5 as described in Example 1. The catalyst contained iron oxide, germanium oxide, chromium oxide and barium oxide in a molar ratio of 100: 2: 1: 1. »

After workup, 2 _r 3,6-Trirnethylphenol was obtained with a selectivity of 99.2 % .

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Example 11

There were p-cresol and methanol in a molar ratio 1: 5j as described in Example 1, but at 5 bar, reacted "The catalyst contained iron oxide, zirconium oxide, chromium oxide and barium oxide in a molar ratio 100: 2: 1: 1.

Bach work-up was obtained with 4.6% of trimethylphenol with a selectivity of 99.2 % .

Example 12

There were phenol, methanol and 7 / asser in the ratio 1: 0.5: 2.5, as indicated in Example 1, but at 330 ⁰ C, implemented. The catalyst contained iron oxide, germanium oxide, chromium oxide and calcium oxide »

The work-up revealed that phenol had reacted with a 95% selectivity to o-cresol and 4.5% selectivity to 2.6-Zylenol. By-products were below 0.5 % *.

Example 13

A mixture of o-cresol and phenol was reacted with methanol and water in a molar ratio of 1: 4: 2.6 in the form of a vapor, as described in Example 1. The overall yield of 2,6-xylenol, based on o-? Cresol and phenol was 99.1 % · the, obtained 2.6-xylenol had a purity of 99.9 % * Mach 2,000 hours, the catalyst still showed a selectivity of 98.2 % ·

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Example 14

O-cresol, methanol and water were reacted in the ratio 1: 2.5: 2.5 »as indicated in Example 1. The catalyst contained iron oxide, zirconium oxide, chromium oxide and lanthanum oxide in a molar ratio of 100: 3: 2: 0 , 5 *

After work-up, 2,6-xylenol was obtained with a selectivity of 98.2 % .

Example 15

Is o-cresol, methanol and water in the ratio 1: 2.5: 2.5, as stated in Example 1, reacted »The catalyst contained iron oxide, tin oxide, chromium oxide and manganese oxide in a molar ratio of 100: 2: 1: 1 After workup, 2,6-xylenol was obtained with a selectivity of 98.7 % . Even after 2,000 hours, the activity and selectivity of the catalyst did not change.

Example 16

Ss were m-cresol, methanol and water in the molar ratio 1: 5: 2.5, as described in Example 1, reacted. The catalyst contained iron oxide, germanium oxide, chromium oxide and lanthanum oxide in a molar ratio of 100: 2: 1: 1.

After workup, 2o3.6-trimethylphenol was obtained with a selectivity of 99 % .

Example 17

There were p-cresol and methanol in a molar ratio of 1: 5, as described in Example 1, but reacted at 5 bar. The catalyst contained iron oxide, zirconium

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oxide, chromium oxide and manganese oxide in a molar ratio of 100: 2: 1: 1.

Bach working up gave 2.4.6-trimethylphenol with a selectivity of 99 % ,

Example 18

Bs were phenol, methanol and water in the ratio 1: 0.5: 2.5, as indicated in Example 1, but at 330 ⁰ C, implemented · The catalyst contained iron oxide, germanium oxide, chromium oxide and manganese oxide.

The workup revealed that phenol had reacted with 95% selectivity to o-cresol and 4.5 / s selectivity to 2,6-cylenol. By-products were below 0.5 % ·

Claims (5)

26.1.1982 ή ± WP C 07 C / 233 366/5 233386 5 "** - ^59783/12 ErfindunqsaηSpruch 1 »Process for the preparation of o-substituted phenols by catalytic reaction of phenols having at least one free o-position with alcohols and / or their ethers, characterized in that phenol and / or mono- and / or dialkylphenols with methanol and / or Dimethyl ether in a molar ratio of 1: 0.1 to 10 at 270 to 390 ⁰ C of the gas phase with a residence time of 0.05 to 10 see. in the presence of a catalyst consisting of oxides of iron, chromium, silicon and of at least one oxide of an alkaline earth metal of lanthanum and manganese, or in the presence of a catalyst consisting of oxides of iron, of chromium, one or more Oxides of germanium, "titanium, zirconium, tin and lead, and consists of at least one oxide of an alkali metal and / or alkaline earth metal of lanthanum and manganese, is reacted, wherein the molar ratios of the components at 100: 0.1 10: 0, 1 - 10: 0.01 - 10, Z- » Process according to item 1, characterized in that ^r is o-cresol with methanol and / or dimethyl ether in a molar ratio 1: 0.5 - 5 used. 3. Process according to items 1 and 2, characterized in that m-cresol or m ~ / p-cresol mixtures are used. Characterized in that one uses sin mixture of o-cresol and phenol 4. The method according to points 1 and 2 in _t ' ν-) _O QQC Ο, R 26.1.1982 L · ά 3 Ö Ό Ό WP C 07 C / 233 365/5 59 783/12 5. The method according to the items 1 to 4, characterized in that one operates at 300 to 330 ⁰ C, 6 * Method according to the points 1 to 5, characterized in that one see at a residence time of 1 to 3.5 see. is working" 7. The method according to points 1 to 6, characterized in that the catalyst contains calcium oxide, barium oxide or Strontiuraoxid.