Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1996-05-03
1997-09-02
Ivy, C. Warren
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568852, 568388, C07C 4702
Patent
active
056634528
DESCRIPTION:
BRIEF SUMMARY
This application is the U.S. National Phase application of PCT/FI94/00387 filed Sep. 2, 1994, published as WO95/07254 on 16 Mar. 1995.
The object of the invention is a new, technically simple but efficient process for the preparation of 2-ethyl-1,3-hexane diol from n-butyraldehyde by aldol condensation in the presence of an alkali metal hydroxide or an alkali earth metal hydroxide. The efficiency of the invention is based on the use of correctly selected catalyst combinations in the reaction.
2-ethyl-1,3-hexane diol is a compound known per se, which is a slightly oil-like, colorless liquid. 2-Ethyl-1,3-hexane diol is used in the main in insecticides, but it can also be used in the preparation of polyesters and in the paint industry as one component in the preparation of pulverous paints.
The preparation of 2-ethyl-1,3-hexane diol from n-butyraldehyde by aldol condensation in the presence of a catalytic amount of an alkali metal hydroxide or an alkali earth metal hydroxide and by subsequent hydrogenation (reduction) is known per se in organic chemistry. The hydrogenation of the intermediate can be carried out either by using reducing agents, e.g. sodium borohydride, or by catalytic hydrogenation.
JP patent publication 2 040 333 describes a process for the preparation of 2-ethyl-1,3-hexane diol by an aldol condensation reaction from n-butyraldehyde in a homogenous system in the presence of an alkali metal hydroxide and by reducing the formed 2-ethyl-3-hydroxyhexanal. n-Butyraldehyde and potassium hydroxide were allowed to react in butanol at 40.degree. C., whereafter the intermediate formed with a yield of 50.4%, 2-ethyl-3-hydroxyhexanal, was hydrogenated by using Raney nickel at a temperature of 100.degree. C. and a pressure of 50 atm for 1 h.
JP patent publication 1 299 240 discloses a process for the preparation of 2-ethyl-1,3-propane diol from n-butyraldehyde by aldol condensation by using alkali metal alkoxides as the catalyst. The reaction was performed in the presence of sodium methoxy in a butanol solution at 40.degree. C. 2-Ethyl-3-hydroxyhexanal formed with a yield of 52.6%, and it was hydrogenated with Raney nickel at a temperature of 100.degree. C. and a pressure of 50 atm.
The process according to the present invention is thus intended for the preparation of 2-ethyl-1,3-hexane diol by a technically simple but efficient process as the result of which a good yield of the end product is obtained. This objective presupposes that the course of the reaction can be controlled significantly better in the aldol condensation step, so that the amount of the hazardous byproduct, 2-ethyl-2-hexanal, formed even in the process according to the JP patent publication described above, can be decreased and thus the yield of the end product can be increased.
It has now been observed, surprisingly, that this objective is attained by correct selection of the catalyst combination used in the aldol condensation step of n-butyraldehyde. Thus the process according to the invention uses, in addition to an alkali metal hydroxide or alkali earth metal hydroxide catalyst, a neutral phase-transfer catalyst for promoting the reaction, whereby the course of the reaction can be rendered more controllable, i.e. the amount of the hazardous byproduct can be considerably decreased and thus the yield of the end product can be increased. The process according to the invention is thus characterized in what is stated in the characterizing clause of Claim 1. Such a combination of alkali metal hydroxide or alkali earth metal hydroxide catalysts and neutral phase-transfer catalysts is a novel and surprising technical solution for the preparation of 2-ethyl-1,3-hexane diol from n-butyraldehyde.
In the process according to the present invention, the preparation of 2-ethyl-1,3-hexane diol takes place in two steps, which are 1) an aldol condensation step and 2) hydrogenation. In step 1), a 2-ethyl-3-hydroxy-hexanal intermediate in accordance with Formula (II) is formed by aldol condensation from n-butyraldehyde (Formula I), and thereafter in s
REFERENCES:
patent: 4215076 (1980-07-01), Stueben et al.
Patent Abstracts of Japan, vol. 14, No. 86, C-690, JP-A-1-299240, Dec. 4, 1990.
Abstract of JP 2-040333, Dialog Inf. Services, Feb. 9, 1990.
Ankner Kjell
Heinola Kalevi
Kulmala Kari
Lahtinen Leila
Rintala Lea
Ivy C. Warren
Neste Oy
Padmanabhan Sreeni
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