GB2114971A

GB2114971A - Production of glycol aldehyde

Info

Publication number: GB2114971A
Application number: GB08204341A
Authority: GB
Inventors: Dr Alec Mee
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1982-02-15
Filing date: 1982-02-15
Publication date: 1983-09-01

Abstract

Glycol aldehyde is produced from formaldehyde by reaction with CO and H2. The catalyst comprises rhodium, a phosphine a fully substituted amide solvent and an activity promoting amount of a strong acid.

Description

SPECIFICATION Production of glycol aldehyde This invention relates to the production of glycol aldehyde.

It is known from European Patent Specification No. 0,002,908 (Monsanto) and US Patent Specification No. 4,200,765 (National Distillers and Chemical Corp.) that formaldehyde may be reacted with carbon monoxide and hydrogen in the presence of a catalyst comprising rhodium and a phosphine in the presence of an amide solvent to produce glycol aldehyde.

We have found that the activity of catalysts in this process is increased when appropriate amounts of strong acids are present.

According to the invention formaldehyde or a polymerised precursor thereof for example paraformaldehyde is reacted with carbon monoxide and hydrogen to produce glycol aldehyde in the presence of a catalyst which comprises rhodium and a phosphine and a fully substituted amide solvent and characterised in that an activity promoting amount of a strong acid is present.

The fully substituted amide is suitably a derivative of a carboxylic acid having at most 6 carbon atoms and the substituents on the nitrogen atoms are suitably alkyl or aryl groups having at most 8 carbon atoms and which preferably together have at most 6 carbon atoms.

Suitably they are ethyl or methyl groups. Very suitable fully substituted amide solvents are dimenthyl formamide, dimethyl acetamide and Nmethyl pyrrolidone.

The catalysts may be introduced as rhodium or a compound thereof together with a phosphine or may be introduced as a preformed complex, for example it may be introduced as a carbonyl, hydrocarbonyl, halide salt, carboxylic acid salt, oxide or the free metal. The phosphine is preferably a tri substituted phosphine, the substituent groups being preferably alkyl, aryl or mixed alkyl, aryl groups having suitably a total of 3 to 40 and preferably 10 to 20 carbon atoms per molecule. If desired diphosphines may be used in which both phosphine groups are tertiary groups.

It is preferred that the ratio of phosphorus atoms to rhodium atoms in the catalyst should be in the range 1 to 10 and preferably 2 to 5. It is believed that during the course of the reaction the catalyst is in the form of a rhodium hydrocarbonyl phosphine complex.

Suitably strong acids include sulphonic acids, for example aromatic sulphonic acids having preferably 6 to 20 carbon atoms, for example paratoluene sulphonic acid or napthalene sulphonic acid, or aliphatic sulphonic acids having 1 to 20 carbon atoms for example methane sulphonic acid; suitably the sulphonic acids have at most 12 carbon atoms per molecule; a-halo carboxylic acids preferably having at most four carbon atoms for example a,a-dichloro propionic acid, mono, di or tri, fluro, chloro, bromo or iodo acetic acid, nitrilo acetic acids, nitro acetic acids, hydroiodic acid or hydrobromic acid.

The concentrations of acid necessary to promote the activity of the catalyst vary according to the nature of the acid and the optimum concentrations should be empirically determined.

In general however from 1 to 100 and preferably 5 to 50 molecules of a sulphonic acid should be supplied per atom of rhodium, from 1 to 50 and preferably from 5 to 30 molecules of hydrobromic acid should be supplied per atom of rhodium, from 1 to 150 and preferably from 5 to 70 molecules of hydroiodic acid should be supplied per atom of rhodium and from 5 to 80 and preferably 10 to 60 molecules of substituted carboxylic acids referred to above should be supplied per atom of rhodium. If hydrochloric acid is used comparatively low concentrations should be employed but the gains in activity with this acid are also comparatively modest.

The concentration of the catalyst is suitably in the range 1 x10-5 to 5x10-2 gram atoms of rhodium per litre.

If desired an auxiliary solvent may be included.

Suitably this is an ether solvent for example dioxan, tetragiyme or dioctyl ether.

The process is suitably carried out at a temperature in the range 60 to 2000C and preferably 100 to 1 400C.

The molar ratio of carbon monoxide to hydrogen is suitably in the range 5:1 to 1:5 and is preferably approximately 1:1.

The process is suitably carried out at a pressure of 50 to 1,000 bars and preferably 1 50 to 350 bars.

Glycol aldehyde initially produced can if desired by hydrogenated to produce ethylene glycol. This may be carried out in situ if the hydrogen partial pressure is increased relative to the carbon monoxide pressure after initial production of glycol aldehyde and if some water is included. Suitably the partial pressure of hydrogen in the hydrogenation is 250-500 bars, the partial pressure of CO is suitably at most 50 bars and the water content is in the range 2% to 10% by weight.

Example 1 A solution of paraformaldehyde (1 molar expressed as formaldehyde) RhCl(CO) [P(CeH5)3]2 (5x 10-4 molar) in dimethyl formamide (50 mls) was placed in a glass liner in a rocking autoclave and exposed to a pressure of 250 bars of carbon monoxide and hydrogen in a molar ratio of 1:1 whilst the temperature was raised to 1 200 C. The pressure was maintained to within 5% by further addition of carbon monoxide and hydrogen in equimolar amounts. After 3 hours the autoclave was cooled and depressurized and the liquid content was analysed by gas iiquid chromatography. The concentration of glycol aldehyde was 65 millimoles per litre and the concentration of methanol was 5 millimoles per litre.The selectivity to glycol aldehyde was 92.9%.

Example 2 Example 1 was repeated except that 1 5 moles of paratoluene sulphonic acid were added per gram atom of rhodium. The concentration of glycol aldehyde in the product was 667 millimoles per litre, the concentration of methanol was 6 millimoles per litre and the concentration of methylformate was 63 millimoles per litre. The selectivity to glycol aldehyde was 90.6%.

Example 3 Example 1 was repeated except that 25 moles of HI were added per gram atom of rhodium. The concentration of glycol aldehyde in the product was 420 millimoles per litre, the concentration of methanol was 1 millimole per litre and the concentration of methylformate was 58 millimoles per litre. The selectivity to glycol aldehyde was 87.7%.

Example 4 Example 1 was repeated with the addition of 5 moles of HBr per gram atom of rhodium. The product contained 387 millimoles of glycol aldehyde per litre, a trace of methanol and 20 millimoles of methylformate per litre. The selectivity to glycol aldehyde was 95.1%.

Example 5 Example 1 was repeated with the addition of 5 molar equivalents of HCI per gram atom of rhodium. The product contained 91 millimoles of glycol aldehyde per litre, no methanol and 38 millimoles of methylformamide per litre. The selectivity to glycol aldehyde was 88.3%.

Example 6 Example 1 was repeated except that 20 moles each of Hi and HBr per gram atom of rhodium were added. The concentration of glycol aldehyde in the product was 1 94 millimoles per litre, of methanol was 72 millimoles per litre and of methylformate was 42 millimoles per litre. The selectivity to glycol aldehyde was 79.8%.

Example 7 Example 1 was repeated except that 25 molar equivalents of trifluroacetic acid per gram atom of rhodium were added. The product contained 268 millimoles of glycol aldehyde per litre, 1 5 millimoles of methanol per litre and 104 millimoles of methylformate per litre. The selectivity of glycol aldehyde was 69.3%.

Example 8 Example 1 was repeated except that instead of RhCI(CO) [P(C6Hs)3]2 the catalyst was PhH(CO) [P(C6H > )3]3 (5x 10-4 molar). Only traces of glycol aldehyde, methanol and methylformate were produced.

Example 9 Example 8 was repeated except that 5 moles of paratoluene sulphonic acid were included per gram atom of rhodium. 217 millimoles of glycol aldehyde per litre, 2 millimoles of methanol per litre and 20 millimoles of methylformate were present in the product. The selectivity to glycol aldehyde was 90.8%.

Glycol aldehyde is hydroxy ethanal.

Claims (Filed on 12.1.83) 1. A process in which formaldehyde or a polymerised precursor thereof is reacted with carbon monoxide and hydrogen to produce glycol aldehyde in the presence of a catalyst which comprises rhodium and a phosphine and a fully substituted amide solvent characterised in that an activity promoting amount of a strong acid is present.

2. A process as claimed in Claim 1 in which the fully substituted amide has at most 6 carbon atoms.

3. A process as claimed in Claim 1 or 2 in which the phosphine is a tri substituted phosphine in which the substituent groups are alkyl, aryl or mixed alkyl aryl groups having a total of 10 to 20 carbon atoms per molecule.

4. A process as claimed in any preceding claim in which the ratio of phosphorus atoms to rhodium atoms in the catalyst is in the range 2 to 5.

5. A process as claimed in any preceding claim in which the strong acid is an aromatic sulphonic acid having 6 to 20 carbon atoms.

6. A process as claimed in Claim 5 in which 5 to 50 molecules of the sulphonic acid are present per atom of rhodium.

7. A process as claimed in any of Claims 1 to 4 in which the strong acid is hydroiodic or hydrobromic acid.

8. A process as claimed in Claim 7 in which 5 to 30 molecules of hydrobromic acid or 5 to 70 molecules of hydroiodic acid are present per atom of rhodium.

9. A process as claimed in any preceding claim in which 1 x10-5 to 5 xl 0-2 gram atoms of rhodium are present per litre.

10. A process as claimed in any preceding claim whenever carried out at a temperature in the range 100 to 1 400C.

11. A process as claimed in any preceding claim in which the molecular ratio of carbon monoxide to hydrogen is in the range 5:1 to 1:5.

12. A process as claimed in any preceding claim which is carried out at a pressure in the range 1 50 to 350 bars.

13. A process for the production of glycol aldehyde whenever carried out substantially as described in any of Examples 2 to 9.

14. Glycol aldehyde whenever produced by a process as claimed in any preceding claim.

1 5. Ethylene glycol whenever produced by the hydrogenation of glycol aldehyde as claimed in

Claims

Claim 14.