DE972256C - Process for the preparation of saturated heterocyclic compounds - Google Patents

Description

Issued on the basis of the first catenary law of July 8, 1949

(WiGBl. P. 175)

FEDERAL REPUBLIC OF GERMANY

ISSUED JUNE 18, 1959

GERMAN PATENT OFFICE

PATENT LETTERING

CLASS 12q GROUP 24 INTERNAT. CLASS CO7d

p 537 Wh / I2q B

David Gwyn Jones, Norton-on-Tees (Great Britain)

has been named as the inventor

Imperial Chemical Industries Limited, London

Process for the preparation of saturated heterocyclic compounds

Patented in the territory of the Federal Republic of Germany from. November 20, 1948 Patent application published June 28, 1951

Patent granted on June 4, 1959 The priority of the UK application dated April 17, 1946 has been claimed

The present invention is a process for the preparation of saturated heterocyclic Compounds that contain a ring-bonded oxygen atom.

According to the present process, saturated heterocyclic compounds of the general formula

c:

H V H

produced by hydrogenating compounds of the general formula

HC =: CH

in the presence of hydrogenation catalysts consisting of a metal or metals of Group VIII of the Periodic Table, where A and B are alkoxy groups with no more than 5 carbon atoms mean.

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The reaction products, a large part of which are new compounds, are intermediates. Pressures above 50 at are not to be used.

The compounds of British patent 595 041, for example, can be used as starting materials be used.

It is known that in the hydrogenation of substituted furans in the liquid phase in an or Absence of solvents by means of hydrogen in the presence of metals of group VIII of the periodic table or of Raney catalysts a selective hydrogenation takes place, which only the C = C double bonds of the furan core saturates, however, substituents, which exclusively borrowed from carbon, hydrogen and oxygen persist, not attack. However, these known procedures did not produce dihydrofurans used as starting materials, rather those that have two double bonds in the ring. Under Based on these reactions carried out with furans could not be foreseen in which way the dihydrofurans, which have a completely different ring bond, show themselves in the catalytic Hydrogenation would behave. So it is surprising that using the subject of the invention forming combination of the reaction conditions using simpler Starting materials valuable products can be obtained.

The process is in the liquid phase and at

Atmospheric pressure or higher pressures up to 50 at. The hydrogenation is carried out at a temperature range from 20 to 130 ^° C. Above 130 ^° C., ring cleavage occurs easily, especially when pressures above atmospheric pressure are used. However, it is more expedient to work at atmospheric pressure, particularly in the interests of a simplified procedure and the equipment.

Suitable catalysts are: platinum, which is either in finely divided form z. B. on silica gel deposited or used as a platinum sponge, nickel, e.g. B. in the form of Raney nickel or deposited on kieselguhr, and cobalt, e.g. B. as Raney cobalt or on diatomaceous earth dejected. Raney nickel here is to be understood as a powdery catalyst, which is obtainable by treating nickel alloys with aqueous acids or alkalis, all of which Dissolve alloy components of the nickel alloy. The ones deposited on substrates Catalysts can e.g. B. 5 to 70 percent by weight of catalytically active metal. All of these catalysts are useful for batch operation. However, the procedure can also be carried out continuously; in this case it is advisable to use a porous catalyst, like a nickel-aluminum or cobalt-aluminum catalyst, to use.

A porous catalyst therefore consists of particles, e.g. B. granules, an alloy containing an or several catalytically active metals together with one or more alloy components contains, which compared to the catalytically active metals, higher solubility in acids or Have alkalis and have been completely or partially dissolved out of the outer layers of the particles are. The interior of the particles forms a solid core made of unchanged alloy; the effective ones outer layers, on the other hand, have a skeletal structure. The particles or pieces can be in different Way to be produced, e.g. B. by crushing the cooled alloy, and can be different be large, but should expediently have a size of 3 to 6 mm. Examples of suitable porous Nickel catalysts are described and manufactured in British Patent 570,843 by dissolving 5 to 30% aluminum from nickel-aluminum alloys, which is 40 to 60 percent by weight Contain nickel and 60 to 40 percent by weight aluminum, by means of aqueous sodium hydroxide solution. Examples of useful porous cobalt catalysts are described in British Patent 611987 and are obtained by extraction of cobalt-aluminum alloys in which the weight ratio of cobalt to aluminum is 15:85 to 55:45 is made with aqueous sodium hydroxide solution.

If 2,5-dimethoxy-2,5-dihydrofuran is used as the starting material, good results are obtained if the catalyst is used at 30 ^° C. and atmospheric pressure when using platinum or Raney nickel. It is necessary to maintain a _pH value of 7 or more when working in the liquid phase, as when working in an acidic medium a tendency to hydrolysis occurs and the working up of the reaction products is difficult.

It is often advisable to carry out the process in the presence of an organic solvent, such as saturated monohydric aliphatic alcohols, ethers or aliphatic esters, e.g. B. ether, Dioxane, tetrahydrofuran and tetrahydropyran.

The stoichiometric amount of hydrogen can be used, but it is more expedient to work with it an excess of hydrogen, e.g. B. a molar ratio to the starting material such as 5: 1 to 7: 1. In the case of continuous operation, the throughput rate of the substituted 2,5-dihydrofuran should be up to 1 1 per liter of catalyst volume and per hour or more.

The invention is illustrated by the following examples

explained. _. . ,

example 1

The mixture is stirred a mixture of 25 cc of 2,5-dimethoxy-2,5 "dihydrofuran, 100 cc of methanol, 1 g sodium carbonate and 1 g of Raney nickel under a hydrogen atmosphere at about 20 ⁰ C. After the recording of the stoichiometric amount of hydrogen is the The reaction product is separated off from the catalyst and distilled under atmospheric pressure

r holds 2,5-dimethoxytetrahydrofuran in one yield of 85%.

Example 2

Dissolve 150 g of 2,5-dimethoxy-2,5-dihydrofuran in 200 cc of methanol and hydrogenated at 30 ⁰ C and

up to 50 atm pressure in the presence of 20 g nickel-diatomite catalyst, which contains 37 weight percent nickel. 2,5-dimethoxytetrahydrofuran is obtained in a yield of 85%.

Claims (4)

Patent claims: i. Process for the preparation of saturated heterocyclic compounds of the general formula H ₂ C CH ₂ Ai I B characterized in that one compounds of the general formula HC = CH A '; B. C. in which A and B are alkoxy groups, in the presence of hydrogenation catalysts which consist of a metal from Group VIII of the Periodic Table, and preferably in the presence of an inert solvent, in the liquid phase at a pressure of not more than 50 atm and a temperature of 20 hydrogenated to 130 ⁰ C with a Pn value of at least 7. 2. The method according to claim 1, characterized in that that when working in batches in the liquid phase as a finely divided catalyst Platinum, platinum on diatomite, platinum sponge, finely divided nickel, nickel on diatomite, finely divided Cobalt or cobalt on diatomite is used. 3. The method according to claim 1, characterized in that that when working continuously in the liquid phase, the catalyst is made of porous Nickel or cobalt. Considered publications: German Patent No. 746307; British Patent No. 428,940; Newer methods of preparative organic chemistry, Verlag Chemie (1944), Vol. I, p. 112; Bulletin de la Societe Cbimique de France, (5). 4, pp. 846, 848, 1630; 1938 (5), 5, p. 1053 and 1054 to 1062; Comptes Rendus, 208 (1939), pp. 359, 360; Journal of the American Chemical Society, Vol. 54 (1932), pp. 1651 to 1657, 4680, 4681 and 4688, 4116, 4117; Handbook of Catalysis, Vol. VII / II, p. 301 and 303. © 909 535/14 6.59