Processes for the preparation of n-butyraldehyde, n-butanol and

Details Processes for the preparation of n-butyraldehyde, n-butanol and Processes for the preparation of n-butyraldehyde, n-butanol and

1999-09-15

2000-12-26

Padmanabhan, Sreeni

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

568449, 568450, 568489, 568491, 568904, C07C 4702

Patent

active

061662658

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a process for the preparation of n-butyraldehyde and/or n-butanol.
n-Butyraldehyde and n-butanol are major products of the chemical industry and are widely used. n-Butyraldehyde, for example, is produced worldwide in amounts of more than 4 million metric tons/year and is used, inter alia, as a starting material for the preparation of plasticizer alcohols. n-Butanol is used in large amounts as solvent, for example for coatings.
Today, n-butyraldehyde is produced on a large industrial scale virtually exclusively by hydroformylation of propene, using various processes which essentially employ cobalt or rhodium hydroformylation catalysts (Kirk-Othmer: Encyclopedia of Chemical Technology, 4th edition, Volum 4, pages 741-746, John Wiley & Sons, New York 1992).
n-Butanol is one of the most important secondary products of n-butyraldehyde in terms of quantity and is obtained therefrom by hydrogenation. Other processes for the preparation of n-butanol, such as the hydrogenation of crotonaldehyde, which in turn is produced by aldol condensation of acetaldehyde, are now only of historical interest or, like the microbiological production of n-butanol by the fermentation of molasses, are only of regional importance (Kirk-Othmer: Encyclopedia of Chemical Technology, 4th edition, Volume 4, pages 694-696, John Wiley & Sons, New York 1992). These processes, in particular the hydroformylation of propene, require high capital costs, for example for the erection of high-pressure plants for the cobalt-catalyzed hydroformylation or for the purchase of the expensive rhodium catalyst, the installations for handling it in the hydroformylation and for working up spent rhodium-containing catalyst solutions. Furthermore, the preparation of n-butyraldehyde by the hydroformylation process requires synthesis gas plants which deliver the synthesis gas required for the hydroformylation. A further disadvantage of the hydroformylation process is the large amount of the byproduct isobutyraldehyde which is inevitably produced and is of little commercial value because it can be further used only in limited amounts.
1,3-Butadiene is a base chemical which is produced in large amounts in steam crackers and is isolated from the C.sub.4 cut of the steam cracker by extraction, for example by means of N-methylpyrrolidone. 1,3-Butadiene is available in large amounts and is a very economical raw material. The preparation of butanol and/or of butyraldehyde starting from the raw material 1,3-butadiene does however entail a number of difficulties. This is due both to the tendency of the 1,3-butadiene to undergo dimerization and polymerization reactions and to the formation of mixtures of 1,2- and 1,4- adducts in the addition reactions. The cause of this chemical behavior is the presence of two conjugated double bonds in the 1,3-butadiene molecule (Kirk-Othmer: Encyclopedia of Chemical Technology, 4th edition, Volume 4, pages 676-683, John Wiley & Sons, New York 1992).
U.S. Pat. No. 2,922,822 and DE-A 2 550 902 disclose that alcohols in the liquid phase react with 1,3-butadiene in the presence of acidic ion exchangers to give the corresponding unsaturated ethers. In U.S. Pat. No. 2,922,822, this reaction is carried out in the presence of a large excess of methanol, which leads to increased formation of the undesirable dimethyl ether. In the process of DE-A 2 550 902, vinylcyclohexene is formed as the main product in this reaction. According to EP-A 25240, the addition reaction of alcohols with 1,3-butadiene is advantageously carried out in the presence of a polar, aprotic solvent, which then has to be distilled off again. According to GB-A 943160, the addition reaction of alcohols is carried out using Bronsted acids in the presence of copper salts.
Futhermore, transition metal complexes having phosphine ligands were used as catalysts for the addition reaction of alcohols with 1,3-butadiene. Chauvin et al. (Bull. Chim. Soc. France (1974), 652) investigated the addition reaction of alcohols with 1,3-butadiene using trialkyl- a

REFERENCES:
patent: 2922822 (1960-01-01), Beach et al.
patent: 4310709 (1982-01-01), Rebafka et al.
patent: 5705707 (1998-01-01), Kanand et al.
Chang, Journal of Organometallic Chemistry, 492, pp. 31-34, 1995.

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