Alcohols, via hydroformylation

The synthesis of tetrahydrofuran derivatives from unsaturated alcohols via hydroformylation intermediates was developed many years ago. Moderate yields are obtained from but-2-en-l,4-diol (Scheme 54)94 but hydroformylation is not the major pathway when coniferyl alcohol is subjected to the oxo process (Scheme 55).9S A more complicated reaction is involved... 

F. G. Helfferich, Detergent-range alcohols via hydroformylation V. Kinetics, Technical Report 203-65, Shell Development Co., 1965. 

Scheme 5.33 Two principal approaches for the production of alcohols via hydroformylation.

Another method for catalyst recycling was introduced by Davies and Hanson [38]. The heterogenization of the rhodium catalyst in an aqueous phase on a silica carrier enabled simple catalyst separation via filtration. Oleyl alcohol was hydroformylated in a thin aqueous phase on the catalyst surface at 50 bar and 100°C. Under these conditions, the yield was 97%, while the catalyst could be recycled several times without any loss of activity. 

Similarly, preparation of a,a-difluorohomoallylic alcohols has been achieved by zinc-mediated addition of CH2=CHCF2Br to carbonyl compounds.29 The reaction is successful with dialkyl ketones as well as aliphatic and aromatic aldehydes (Equation 4.12). The allylation products are particularly useful since the alkene may be oxidized to an aldehyde,32 epoxide,33 or converted to a 8-lactone34 via hydroformylation. 

The desired a-alkenes in the C10-C20 range are used as feedstock in the production of detergent alcohols and in the synthesis of lubricants, the C6-Q0 alkenes are used as plasticizer alcohols in phthalates for PVC, and as comonomers in low-density polyethylene, and a variety of other products. The internal by-products are mainly used for the production of alcohols via a cobalt-catalyzed hydroformylation. 

The SCCO2/IL flow process developed for hydroformylation is applicable to other homogeneous catalysis reactions, including enzymatic reactions. For instance, two groups independently reported the kinetic resolution of racemic secondary alcohols via transesterification by Upase in an scC02/[bmim][NTf2] system (Scheme 82). The reaction is advantageous with respect to the conventional process because of the ease of the product/enzyme and product/solvent separations. 

Structure (ATO) gives a product distribution that is dominated by adipic acid. This is thought to result because the narrower channels inhibit the release of cyclohexanol and cyclohexanone and the reaction proceeds further to the more mobile linear products, such as adipic acid. Selectivity is also observed in the aerial oxidation of linear alkanes. If the reaction is performed over large-pore solids, w-alkanes are oxidised preferentially at carbon atoms at C2 and C3 positions in the chain, in accordance with the C-H bond strengths at these positions. If a small-pore structure such as CoAPO-18 is used, however, the product selectivity favours Cl oxyfunctionalised products. The synthesis of terminally oxidised alkanes would be of use for many applications, because linear terminal alcohols could be prepared from alkane feedstocks, rather than from a-olefins (via hydroformylation). 

An additional petrochemical route is practiced by Sasol Italy SpA (see Figure 13.3). This process starts with the dehydrogenation of paraffins to produce olefines, which are then reacted with carbon monoxide (via hydroformylation) to produce Oxo alcohols containing 40-50% mostly methyl-branching. 

In a patent by Mitsubishi, it is available via hydroformylation of limonene and subsequent acid-catalyzed intramolecular cyclization of the aldehyde [1]. The alcohol can also be produced in one step by Pt/Sn-catalyzed hydroformylation, suggested by a protocol of Gusevskaya and coworkers (Scheme 5.123) [2, 3]. Platinum and tin are essential for the cychzation in the last step. Alternatively, the tandem reaction has been investigated in detail with rhodium complexes based on PPhg, P[0(o-fBu)Ph]3, or PPTS (pyridinium / -toluenesulfonate)... 

Hydroxy aldehydes can be prepared via hydroformylation of corresponding unsaturated alcohols. In particular, tertiary hydroxy olefins have seen broad application as substrates. For example, IFF claimed the reaction of 2-methyldodec-ll-en-2-ol with syngas at 700 psi ( 48 bar) and 120-140 C (Scheme 6.40) [132]. Under these conditions, preferentially the terminal aldehyde was formed. 

Ma.nufa.cture. Most butanediol is manufactured in Reppe plants via hydrogenation of butynediol. Recendy an alternative route involving acetoxyiation of butadiene has come on stream and, more recendy, a route based upon hydroformylation of allyl alcohol. Woddwide butanediol capacity has climbed steadily for many years. In 1990 it was estimated to be 428,000 metric tons (141), as compared to a Htde more than 70,000 metric tons in 1975... 

Eatty alcohols, prepared from fatty acids or via petrochemical processes, aldol or hydroformylation reactions, or the Ziegler process, react with ammonia or a primary or secondary amine in the presence of a catalyst to form amines (10—12). 

The octylphenol condensate is used as an additive to lubricating oils and surface-active agents. Other uses of dimer are amination to octylamine and octyldiphenylamine, used in mbber processing hydroformylation to nonyl alcohol for phthalate production and carboxylation via Koch synthesis to yield acids in formulating paint driers (see Drying). 

Propanediol is a colorless liquid that boils at 210-211°C. It is soluble in water, alcohol, and ether. It is an intermediate for polyester production. It could be produced via the hydroformylation of ethylene oxide which yields 3-hydroxypropionaldehyde. Flydrogenation of the product produces 1,3-propanediol. 

With the excephon of methanol and ethanol, most alcohols are produced from olefins, either through hydration [10] or via a hydroformylation-hydrogenation sequence (Scheme 4-1) [11]. 

Saturated ketones and aldehydes have been reduced to alcohols using Co2(CO)8-phosphine (P) mixtures at high H2 pressures, probably via the coordinatively unsaturated species HCo(CO)2P (187). A reassessment of experimental data on hydrogenation of aromatics (A) catalyzed by Co2(CO)8 under hydroformylation conditions has led to the suggestion that free radicals rather than organocobalt complexes are involved (188), e.g.,... 

In a similar fashion, allylboronates can be used as allylation reagents under hydroformylation conditions. Thus condensed 1,5-oxazadecalin systems are achieved via tandem hydroformylation/allylboration/hydroformylation sequences starting from an N-allyl-y-amidoallylboronate (Scheme 23) [77,78]. The aldehyde obtained from a regioselective hydroformylation undergoes diastereoselective intramolecular allylboration to give an intermediate al-lylic alcohol derivative. The reaction does not stop at this stage, since this... 

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