Butanol, from propene

The synthesis of aldehydes from alkenes known as hydroformylation using CO and hydrogen and a homogeneous catalyst is a very important industrial process [204]. Today, over seven million tons of oxoproducts are formed each year using this procedure, with the majority of butanal and butanol from propene. To further increase the efficiency of this process it can be combined with other transformations in a domino fashion. Eilbracht and coworkers [205] used a Mukaiyama aldol reaction as a second step, as shown for the substrate 6/2-63 which, after 3 days led to 6/2-65 in 91% yield via the primarily formed adduct 6/2-64 (Scheme 6/2.13). However, employing a reaction time of 20 h gave 6/2-64 as the main product. 

The only industrial application, the synthesis of butanol from propene (Reppe synthesis), was not very successful (297). This reaction is catalyzed by iron carbonyls in the presence of tertiary ammonium salts the trinu-clear cluster anion [HFe3(CO) ] detected in the reaction mixture has been discussed as the active species (298). Spectroscopic studies under CO pressure, however, showed the trinuclear anion [HFe3(CO) ]- to be converted into the mononuclear species [HFe(CO)4] (299), and this anion is now assumed to be the catalyst in the Reppe reaction (290). 

The reaction of alkenes (and alkynes) with synthesis gas (CO + H2) to produce aldehydes, catalyzed by a number of transition metal complexes, is most often referred to as a hydroformylation reaction or the oxo process. The discovery was made using a cobalt catalyst, and although rhodium-based catalysts have received increased attention because of their increased selectivity under mild reaction conditions, cobalt is still the most used catalyst on an industrial basis. The most industrially important hydrocarbonylation reaction is the synthesis of n-butanal from propene (equation 3). Some of the butanal is hydrogenated to butanol, but most is converted to 2-ethylhexanol via aldol and hydrogenation sequences. 

Qg-acid from propene tetramer tert. Butanol 15-25 6% Qi-Dicarboxylic acids 30% Pivalic acid 43% Cjg-acid... 

Hydroformylation is an important industrial process carried out using rhodium phosphine or cobalt carbonyl catalysts. The major industrial process using the rhodium catalyst is hydroformylation of propene with synthesis gas (potentially obtainable from a renewable resource, see Chapter 6). The product, butyraldehyde, is formed as a mixture of n- and iso- isomers the n-isomer is the most desired product, being used for conversion to butanol via hydrogenation) and 2-ethylhexanol via aldol condensation and hydrogenation). Butanol is a valuable solvent in many surface coating formulations whilst 2-ethylhexanol is widely used in the production of phthalate plasticizers. 

Zr(allyl)3Br gives mainly, but not exclusively, a center of type (XV). This follows from the observation that reaction of Zr(allyl)3Br with silica gives two molecules of propene per metal atom and no halogen is liberated. Addition of excesses of n-butanol to the SiCb/Zrfallyl Br reaction product however gives one molecule of propene per metal atom and one molecule of HBr per metal atom is liberated with excess benzoic acid solution. The structure of (XVI) was determined in a similar manner. Chromium allyls give transition metal centers with structure (XVII). 

In connection with the methoxy participation, the gas-phase pyrolytic elimination of 4-chloro-1 -butanol was investigated177. The products are tetrahydrofuran, propene, formaldehyde and HCl. It is implied that the OH group provides anchimeric assistance from the fact that, besides formation of the normal unstable dehydrochlorinated intermediate 3-buten-l-ol, a ring-closed product, tetrahydrofuran, was also obtained. The higher rate of chlorobutanol pyrolysis with respect to chlorethanol and ethyl chloride (Table 27) confirmed the participation of the OH group through a five-membered ring in the transition state. 

Functionalization of hydrocarbons from petroleum sources is mainly concerned with the introduction of oxygen into the hydrocarbon molecule. In general, two ways are open to achieve oxygen functionalization oxidation and carbonylation. Oxidation is commonly encountered in the synthesis of aromatic acids, acrolein, maleic anhydride, ethene oxide, propene oxide, and acetaldehyde. Hydroformylation (CO/H2) (older literature and the technical literature refer to the oxo reaction) is employed for the large-scale preparation of butanol, 2-ethylhexanol, and detergent alcohols. The main use of 2-ethylhexanol is in phthalate esters which are softeners in PVC. The catalysts applied are based on cobalt and rhodium. (For a general review see ref. 3.)... 

Propene hydroformylation can lead to products with a linearity ranging from 60 to 95%, depending on the phosphine concentration. At very high phosphine concentration the rate is low, but the linearity achieves its maximum value. Low ligand concentrations, with concomitant low linearities, will give turnover frequencies in the order of 10,000 mol mol-1 h 1 at 10 bar and 90°C. In the presence of carbon monoxide this rhodium catalyst has no activity for hydrogenation and the selectivity, based on starting material, is virtually 100%. The butanal produced contains no alcohol and can be converted both to butanol and to other products, as desired. 

Additional experiments with controlled coke formation were performed in order to study the effect of coke nature and location on the MTO reaction. Internal coke was obtained using propene while external coke was obtained using i-butene produced from i-butanol. i-Butanol was introduced by switching to a carrier gas saturated in theimostated bottles containing the liquid. After the desired coke content w is reached by using propene or i-butene/i-butanol, methanol or DME was introduced at the standard MTO conditions. The pore volume of fresh and coked catalysts was determined gravimetrically by TPD of catalyst samples saturated with water at room temperature. 

Figure 2. Coke formation with time on stream MTO o MTO after 0.63 wt% coke from i-butanol propene A DTO at WHSV=417 h + DTO at WHSV=600 h. ...

CHF CFa, from hexafiuoropropene and propene at 250 °C, the formation of addacts between ethyl a>fluoroacrylate and chlorotrifluoro- or tetrailuoro-ethylene, preparation of various 1,1,2-trifluorocyclobutanes as anaesthetics, and the formation of adducts (78 X = Y = F or Cl X = F, Y = O) from diethyl itaconate at 180 °C, where diethyl dtraconate failed to react. 2-Alkoxy-3-phenylcyclobut-2-enoiies are formed when the adducts of styrene and CF tCFCl or CFgiCFj are treated with potassium hydroxide in ethanol or potassium t-butoxide in t-butanol, respectively. The adducts of / -nitro- and p-methoxy-phenylacetylene and chlorotrifluoro-ethylene may be hydrolysed by concentrated sulphuric acid to arylcyclo-butenediones. Tetrafluoroethylene adds photochemically to 3p-acetoxy-pregna-5,16-dien-20-one by [2 + 2] addition to the C—C bond of the enone grouping and by [2 + 4] addition to this function. ... 

Butanols exist as four isomers w-butanol, isobutanol (2-methyl-l-propanol), 2-butanol, and ferf-butanol (2-methyl-2-propanol). Both n- and isobutanols are obtained by propene hydroformylation followed by aldehyde hydrogenation [route (b) in Topic 5.3.1 and Section 6.14]. 2-Butanol and tert-butanol are industrially produced from hydratization of 1-butene and isobutene, respectively [(route (c) in Topic 5.3.1]. 

Major methods for isobutene production are from a C4 stream of a steam cracker, from a catalytic cracker butene-butane stream, through dehydration of tert-butanol (which is obtained from a propene oxide process) and through isomerisation of n-butane to isobutene and subsequent dehydrogenation to isobutene (Obenaus et al. 2000 van Leeuwen et al. 2012 Romanow-Garcia et al. 2007). 

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