Formaldehyde hydroformylation

Fluorites inclusions, 869 Formaldehyde hydroformylation catalysts, rhodium complexes, 261 Forraamidinesulfinic acid technetium complexes, 974 Formate dehydrogenases bacteria... 

MMA and MAA can be produced from ethylene [74-85-1/ as a feedstock via propanol, propionic acid, or methyl propionate as intermediates. Propanal may be prepared by hydroformylation of ethylene over cobalt or rhodium catalysts. The propanal then reacts in the Hquid phase with formaldehyde in the... 

Other routes have been tried starting from formaldehyde or paraformaldehyde. One process reacts formaldehyde with carhon monoxide and H2 (hydroformylation) at approximately 4,000 psi and 110°C using a rhodium triphenyl phosphine catalyst with the intermediate formation of glycolaldehyde. Glycolaldehyde is then reduced to ethylene glycol ... 

Methyl-l-hexanol has also been prepared by the reaction of 2-hexylmagncsium halides with formaldehyde,3 the reduction of 2-mctliylliexanoic acid or its ester,4 5 and by hydroformylation of 1-hexene6"8 among others. 

Methanol is used in industry as a raw material for formaldehyde (40-50%), as a solvent, and for producing, for example, acetic acid by hydroformylation. The latter is used, for example, to make precursors for polymers. 

The hydroformylation of acrolein cyclic acetals has received considerable attention in the recent patent literature as a route to 1,4-butanediol (76-52). This diol is a comonomer for the production of polybutylene terephthalate, an engineering thermoplastic. The standard method for its manufacture has been from acetylene and formaldehyde, as shown in Eqs. (37) and (38) ... 

Hydroformylation of hetero olefins such as carbonyl compounds is not known to proceed with significant levels of efficiency, whereas the hydroformylation of olefins has been developed to a sophisticated stage. Generally, aldehydes resultant from the latter process exhibit a low propensity to undergo further hydroformylation, with the exception of some activated aldehydes. The rhodium-catalyzed hydroformylation of formaldehyde is the key step in the synthesis of ethyleneglycol from synthesis gas. Chan et al. found... 

Hydroformylation of formaldehyde to give glycolaldehyde is an attractive route from syn-gas toward ethylene glycol. The reaction is catalysed by rhodium arylphosphine complexes [39] but clearly phosphine decomposition is... 

The second synthesis is based on the conversion of undecanal into 2-methyleneundecanal by reaction with formaldehyde in the presence of catalytic amounts of amines [15]. Hydrogenation of 2-methyleneundecanal yields methylnonylacetaldehyde. A convenient process starts from 1-decene hydroformylation gives a mixture consisting mainly of undecanal and 2-methyldecanal. Reaction of the crude product with formaldehyde in the presence of dibutylamine yields a mixture containing over 50% 2-methyleneundecanal. After hydrogenation of the double bond, pure 2-methylundecanal is separated from by-products by fractional distillation [16]. 

The possible intermediacy of formaldehyde in CO hydrogenation has been addressed above with regard to the cobalt catalytic system. Fahey has observed a small amount of 1,3-dioxolane (the ethylene glycol acetal of formaldehyde) as a product of the rhodium system (43). Thus, there is evidence that formaldehyde or a complexed form of this molecule could be an intermediate in the CO reduction process by this system. Rhodium catalysts are indeed found to be useful for the hydroformylation of formaldehyde to glycolaldehyde (159-161) methanol is a by-product in these reactions. 

In addition to C—C bonds, [RhCl(CO)(PPh3)2] (71) has been shown to catalyze the hydroformylation of formaldehyde to give glycol aldehyde (equation 62).336 Small amounts of methanol were obtained as a by-product. The reaction requires N,JV-dialkylamides as solvents, otherwise methanol is the major product and no glycol aldehyde is formed. Coordinated amide solvent was thought... 

The hydroformylation of formaldehyde, a route to ethylene glycol via glycolalde-hyde, may involve the steps... 

Other routes to MMA start from ethylene, propylene or propyne and involve metal catalysis at some stage of multi-step transformations for example by the hydroformylation of ethylene to intermediate propionaldehyde, oxidation to propionic acid, followed by condensation with formaldehyde. The Pd-catalyzed carbonylation of propyne to MMA is a further method. However only the ethylene route has found some industrial application (see Chapter 4, Section 4.3.1). 

Ru3(CO)i2/Talkylbenzimidazoles showed high selectivity for ethylene glycol [13]. A mechanistic study of this reaction showed that RuH2(CO)3(l-methylbenzimid-azole) is formed, and this complex is considered to be the active species. 1-Methyl-benzimidazole enhances both the rate of the formation of formaldehyde from syngas and the rate of the hydroformylation of formaldehyde [14]. 

The same catalyst precursor, generated from [(EDTA)RuCI] which is also water soluble, was used for the hydroformylation of allylic alcohol under the same reaction conditions (//). At 50 bar and 130°C, in water as solvent, 4-hydroxybutanal was produced [Eq. (5)], together with about 2% of formaldehyde. However, the reaction proceeded further to give butane-1,4-diol by hydrogenation and y-butyrolactone as well as dihydrofuran by cyclization [Eq. (6)]. The same catalytic cycle as that proposed in Scheme 3 can be considered. A kinetic investigation revealed a first-order dependence on the ruthenium complex concentration and on the allyl alcohol... 

A third homogeneously catalyzed process, on the basis of formaldehyde condensation with propanal to give methacrolein and subsequent oxidation to methacrylic acid, was commercialized in 1990 by BASF. Application of this process is limited by the availability of cheap propanal, produced by large-scale ethylene hydroformylation (cf. Section 2.1.1). 

In addition to the olefin hydroformylation, the hydroformylation of formaldehyde has become particularly interesting since it provides access to ethylene glycol from syngas without involving ethylene. The hydroformylation of formaldehyde, normally employed as polymer (paraformaldehyde), yields glycolaldehyde... 

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