DE1593361B - Process for the preparation of aromatic hydroxy compounds - Google Patents

Description

3 4

The rate of at least 2 hours at 600 to 700 ° C for the cycloketone with the catalyst was 4 seconds

Treat air to maximize catalytic acti- ves. The analysis of the reaction product showed the following

vity and undesirable side reactions, low composition: 84.1 percent by weight of 4-Hy-

z. B. decomposition of the ketone molecule, to verroxybenzothiophene, 10.0 percent by weight 4,5,6,7-Te-

avoid. 5 trahydro-4-oxobenzothiophene and 5.9 weight percent

A unique feature of this process is the absence of by-products. The yield of 4-hydroxy

in that no hydrogen addition to the maintenance benzothiophene, based on the converted

processing of the catalytic activity is required. The raw material was 93.5%

accordingly, no hydrogen is used in the process. .

puts. Processes in which, for example, platinum io üeispiez

group metals are used as catalysts, a feed mixture containing 4,5,6,7-tetrahydro-4-oxo-

require the addition of hydrogen to the cataly- benzothiophene was contained in the vapor phase

maintain table activity. 475 to 500 ° C passed over a catalyst that

The method according to the invention is carried out in the 10% by weight MoO ₃ on activated aluminum vapor phase. Accordingly, it must contain 15 oxyd. The molar ratio of the components to the reaction temperature must be so high that the starting mixture in the feed mixture corresponds to 3 mol of water per mol of cycloketone evaporated. Generally, Tem-4,5,6,7-tetrahydro-4-oxobenzothiophene. The contact temperatures between 350 and 700 ° C, preferably at the time of the cycloketone with the catalyst was 425 to 600 ° C, used. , 4 seconds. The analysis of the reaction product

The process is preferably continuous with the following composition: 46.0 percent by weight

accomplished. In a typical process by 4-hydroxybenzothiophene, 49.8 weight percent 4.5,

The vaporized mixture of cyclo- 6,7-tetrahydro-4-oxobenzothiophene and 4.2 weight-

ketone and steam through a fixed bed (or one percent by-products. The yield of 4-hydroxy-

Fluidized bed) of the catalyst. The contact time of the benzothiophene, based on the converted

Cycloketone with the catalyst, which is reversed raw material, was 91.7%.

in relation to the temperature is between 0.5 and 8 seconds. .

den, preferably between 1 and 6 seconds. This ü e 1 s ρ 1 e 1 J

corresponds to room flow velocities (room- A feed mixture containing 4,5,6,7-tetrahydro-4-oxo-

parts of liquid input / space part / catalyst / hour) of benzothiophene was in the vapor phase at

2.8 to 0.2, preferably from 1.4 to 0.3 when using 30 625 ° C passed over a catalyst containing 95% Cr ₂ O ₃

the optimal usage ratio. * included. The molar ratio of the components in one

. -I _{1 set} mixture corresponded to 3 moles of water per mole of 4.5,

Example 1 6,7-tetrahydro-4-oxobenzothiophene. The contact time

A feed mixture, the 4,5,6,7-tetrahydro-4-oxo of the cycloketone with the catalyst was 2 seconds

benzothiophene was found in the vapor phase at 35 den. The analysis of the reaction product showed the following

525 ° C passed over a catalyst of 20 parts by weight composition: 82.0%

weight percent Fe ₂ O ₃ on activated aluminum oxide 4-hydroxybenzothiophene, 3.4% 4,5,6,7-tetrahydro-

contained. The molar ratio of the components in 4-oxobenzothiophene and 14.6% by-products. the

The mixture used corresponded to 3 moles of water per mole of 4.5, the yield of 4-hydroxybenzothiophene, based on

ö ^ -Tetrahydro- ^ oxobenzothiophene. The contact time of 40 converted starting product was 85%

Claims (3)

1 2 Presence of water vapor at a molar ratio of claims: of water vapor to ketone between 1: 1 and 50: 1, the process according to the invention is characterized by 1. A process for the production of aromatic characterized in that one heterocyclic ketones which contain a hydroxy compound of at least partially hydrogenated hydroaromatic ring with 6 carbonated c} 'clic ketones by catalytic lenstoffatomen and a keto oxygen atom on a vapor phase dehydrogenation at elevated temperatures of these carbon atoms , with a molar ratio in the presence of water vapor with a ratio of H ₂ O: ketone between 1: 1 and 10: 1 in an molar ratio of water vapor to ketone zvvi- essence of a metal oxide of group VIb or see 1: 1 and 50: 1, characterized by the fact that the iron subgroup of Group VIII of the Periodic drawing is that heterocyclic ketones, see the system, are dehydrogenated as catalysts. The process according to the invention, a fused-on hydroaromatic ring, is distinguished by a high output with 6 carbon atoms and a keto oxygen atom and good selectivity. One of these carbon atoms is preferably contained, in which the molar ratio of water vapor to heterocyclic molar ratio of H ₂ O: ketone is between 1: 115 and 3: 1. and 10: 1 in the presence of a metal oxide belonging to the group according to the process according to the invention VIb or the iron subgroup of the hydrogenating ketone group is a heterocyclic compound VIII of the Periodic Table as a catalyst dehydrated with at least one condensed hydroaromatic. see ring with 6 carbon atoms, with few 2. The method according to claim 1, characterized in that «20 least one of these carbon atoms is a keto acid, that a molar ratio of hydrogen atoms is bonded and at least two of these steam to heterocyclic! Ketone of 3: 1 carbon atoms are saturated with hydrogen, turns. So the ketone has a condensed ring structure 3. The method according to claim 1 or 2, characterized with a heterocyclic ring to which the hydro marked that one is fused on as a heterocyclic ketone 25 aromatic six-membered ring. The ge-4,5,6,7-tetrahydro-4-oxobenzothiophene, 2,3,4,5,6, saturated heterocyclic ketone can be substituted with lower 7-hexahydro-4-oxobenzothiophene or 4,5,6,7-Te-alkyl radicals (C _{1 -C 3} ), nitrile groups or ester tetrahydro-6-methyl-4-oxobenzothiophene are used. groups (- COOR), in which R is a lower alkyl radical with 1 to 3 carbon atoms, be substituted. Examples 30 such heterocyclic ketones are 5,6,7,8-tetra- hydro-5-oxoquinoline, 4,5,6,7-tetrahydro-4-oxobenzofuran, 4,5,6,7-tetrahydro-4-oxobenzothiophene, 2,3,4, The invention relates to a process for the production of 5,6,7-hexahydro-4-oxobenzothiophene and 4,5,6,7-Tevon aromatic hydroxy compounds, such as 4-hy- trahydro-6-methyl-4-oxobenzothiophene.
droxybenzothiophene, after an improved dehydration 35 As already mentioned, the invention contains dration in the vapor phase. Starting mixture of the process the hydrogenated cyclo- The compound 4-hydroxybenzothiophene is a ketone and water as water vapor. An inert inorganic Starting compound for the synthesis of thinning gas, such as nitrogen or flue gas, can N-substituted benzothienyl carbamates, which are used in addition to water vapor. It have excellent pesticidal properties. This Aus 40 has been shown, however, that optimal yields and transition connection has so far been achieved through implementation of optimal catalytic activity then 4-keto-4,5,6,7-tetrahydrobenzothiophene and sulfur when using water vapor as the only carrier gas according to Fieser and K e η η e 11 y (J. Am. Chem. Soc, 57, will. Pp. 1611 to 1616 [1935]). The best The molar ratio of water as steam to hy- Yields, which are mentioned by the authors, 45 third cycloketone is between 10 and 1: 1. With supplements at 46%. The application of other dehydration additional use of a diluting gas to process, z. B. catalytic dehydrogenation, water vapor is found to have a ratio of 2 moles due to the nature of the material to be dehydrogenated - inert gas (nitrogen) to 1 mole of water vapor to 1 mole sword. Care must be taken to ensure that one of the hydrogenated cycloketones is suitable
substantial conversion to benzothiophene is avoided. As catalysts for the steam according to the invention, what would be a total loss for the process dar-phase dehydrogenation process would be oxides of Mestellen. metals of groups VIb and VIII (subgroup iron) From US Pat. No. 2,628,985 there is a ver of the Periodic System on pages 56 and 57 by Lange's drive for the production of phenols from Cyclo-Handbook of Chemistry, 10th edition (1961), out of hexanone by catalytic vapor phase dehydration. given by Handbook Publishers, Inc., Sandusky, used at elevated temperature in the presence of 'Ohio. The iron subgroup consists of known water vapor, with a molar ratio of Fe, Co and Ni. Accordingly, water vapor to ketone between 1: 1 and 50: 1 are used as catalysts - Cr ₂ O ₃ , MoO ₃ , WO ₃ , Fe ₂ O ₃ , Ni ₂ O ₃ , Co ₂ O ₃ and UO ₃ are added. The dehydrogenation catalyst is used at. Excellent results are obtained with this process from iron oxide, chromium oxide and ⁶⁰ when these catalytic oxides are used alone, ie without an alkali compound. The phenol yield depends on the carrier or diluent used. The kata between 80 and 86 ° / ₀ ; in the production of lytic oxides, however, inert carriers such as 3,5-xylenol can be used only 50%, based on the alundum, pumice stone or aluminum oxide, or on the reacted starting material. active carriers, such as activated aluminum oxide, Based on this known production aroma- ⁶ 5 be brought. When using supported catalysts of table hydroxy compounds at least partially, these preferably contain at least 10% of the hydrogenated cyclic ketones by catalytic catalytic oxide. It was found to be expedient to carry out the vapor phase hydrogenation at elevated temperature in the above-mentioned catalysts before it