Iso-butyraldehyde

An example of such recycling in a parallel reaction system is in the Oxo process for the production of C4 alcohols. Propylene and synthesis gas (a mixture of carbon monoxide and hydrogen) are first reacted to n- and iso-butyraldehydes using a cobalt-based catalyst. Two parallel reactions occur7 ... 

This substrate was prepared by aldol condensation of tetralone with iso-butyraldehyde in the presence of aqueous sodium hydroxide[9]. 

The allenylindium intermediates are prepared by treatment of the aziridines with Pd(PPh3)4 in THF-HMPA containing 1 equivalent of water. In the presence of iso-butyraldehyde the expected adducts were formed with excellent diastereoselectivity (Tables 9.56 and 9.57). Interestingly, the reaction did not proceed in the absence of water. It is suggested that water is needed to protonate the sulfonamide anion of the initially formed allenyl palladium species (Eq. 9.150). 

It used to be that the iso-butyraldehyde had to be split out before the dimerization reaction, but catalyst improvements have permitted cogeneration of both C4 alcohols and 2-EH. 

The catalytic activity of a lanthanum (R)-BINOL complex tethered either on silica (62a) or MCM-41 (62b) was evaluated for the enantioselective nitroaldol reaction of cyclohexanecarboxaldehyde (Se), hexanal (Sf), iso-butyraldehyde (Sg) and hydro-cinnamaldehyde (Sh) with nitromethane inTHF (Scheme 12.22) [166]. The silica-anchored lanthanum catalyst 62a gave 55-76% e.e. and yields up to 87%, while the PMS-immobilized catalyst 62b revealed slightly higher e.e.s (57-84%) for the same aldehydes. The homogeneous counterparts showed similar catalytic performance, albeit within a shorter reaction time. The increased enantioselectivity observed for the MCM-41 hybrid catalyst 62b was explained by transformations inside the channels, which is also reflected by lower yields due to hindered diffusion. The recyclability of the immobilized catalysts 62b was checked with hydrocin-namaldehyde (Ph). It was found that the reused catalyst gave nearly the same enantioselectivities after the fourth catalytic run, although the time period for achieving similar conversion increased from initially 30 to 42 h. 

The hydroformylation reaction, also known as the oxo reaction, is used extensively in commercial processes for the preparation of aldehydes by the reaction of one mole of an olefin with one mole each of hydrogen and carbon monoxide. The most extensive use of the reaction is in the preparation of normal- and iso-butyraldehyde from propylene. The ratio of the amount of the normal aldehyde product to the amount of the iso aldehyde product typically is referred to as the normal to iso (N I) or the normal to branched (N B) ratio. In the case of propylene, the normal- and iso-butyraldehydes obtained from propylene are in turn converted into many commercially-valuable chemical products such as n-butanol, 2-ethyl-hexanol, trimethylol propane, polyvinylbutyral, n-butyric acid, iso-butanol, neo-pentyl glycol,... 

Methyl Isobutyl Carbinol Methyl Amyl Alcohol Methyl Isobutyl Ketone Methyl Amyl Alcohol Iso-Butyraldehyde Isobutyric Acid Iso-Butyraldehyde Isobutyronitrile... 

Isomorphous replacement in isotactic polyaldehydes was shown by A. Tanake, Y. Hozumi, K. Hatada, S. Endo, and R. Fujishige (42). These authors studied the binary polymer systems formed by acetaldehyde, propionaldehyde, n-butyraldehyde, iso-butyraldehyde and w-heptanal. All the copolymers are crystalline over the whole range of compositions. In the case of binary copolymers of acetaldehyde, propionaldehyde and K-butyraldehyde the unit cells have the same tetragonal space group UJa, with the same chain axis (4.8 A), while the dimensions of the a axis change continuously as a function of the copolymer composition. In the case of copolymers of isobutyraldehyde with other aldehydes, the continuous variation of the lattice constants a and c were observed. 

A kinetic study of the hydroformylation has been carried out306 and the mechanism proposed by Wilkinson (Scheme 16) was extended to express both the associative and dissociative modes of alkene coordination298 and the formation of n- and iso-butyraldehydes. High-pressure IR spectroscopy using CO and either H2 or D2 has confirmed the formation of [RhH(CO)2(PPh3)2] in these reactions.307... 

Fig. 21. pH-Dependence of the limiting currents of some saturated aldehydes on pH. (1), (2) acetaldehyde, 3-phenylpropionaldehyde (3) iso-butyraldehyde (4) 2-ethylbutyraldehyde (5) phenylacetaldehyde (6) 2-phenylpropionaldehyde (7) formaldehyde. Waves were recorded in borate and barbiturate buffers and in ithium hydroxide solutions. General base catalysis effect was small... 

At the beginning of the 1970s Ugi et al. [29] reported the use of (+)-a-ferrocenyle-thylamine 25a in the condensation with iso-butyraldehyde, benzoic acid and tcrt-butylisocyanide (Scheme 1.11). The Ugi adduct 26 could be obtained with different diastereomeric excesses, varying solvent, concentration and temperature in analogy [29] with the above described a-methylbenzylamine. Following this first study, different a-ferrocenylalkylamines have been employed [30, 31] and improvements in... 

Benzaldehyde (entry 3) and the hindered iso-butyraldehyde (entry 2) give the lowest yields. Sakurai and Hosomi next extended the addition of allylsilane 1 to enones 8 [7]. In the presence of TiCU, the 1,4-adduct 9 is obtained in good yields (Scheme 13.3). It is interesting to note that allylcuprates are less selective than allylsilanes and that / ,/ -disubstituted enones react efficiently, leading to ketones bearing a quaternary carbon center at the / position (entry 3). 

Surprisingly, the catalytic potential of proline (1) in asymmetric aldol reactions was not explored further until recently. List et al. reported pioneering studies in 2000 on intermolecular aldol reactions [14, 15]. For example, acetone can be added to a variety of aldehydes, affording the corresponding aldols in excellent yields and enantiomeric purity. The example of iso-butyraldehyde as acceptor is shown in Scheme 1.4. In this example, the product aldol 13 was obtained in 97% isolated yield and with 96% ee [14, 15]. The remarkable chemo- and enantioselectivity observed by List et al. triggered massive further research activity in proline-catalyzed aldol, Mannich, Michael, and related reactions. In the same year, MacMillan et al. reported that the phenylalanine-derived secondary amine 5 catalyzes the Diels-Alder reaction of a,/>-un saturated aldehydes with enantioselectivity up to 94% (Scheme 1.4) [16]. This initial report by MacMillan et al. was followed by numerous further applications of the catalyst 5 and related secondary amines. 

Hydration of the double bond of 288 gave 289, on which a Reformatski reaction was performed to yield harringtonine (107) together with epiharring-tonine (because of the two modes of hydration of the double bond in 288) (Scheme 59). The required ester (283) was prepared by first condensing iso-butyraldehyde with malonic acid to form 290, followed by isomerizing with... 

This effluent then goes to a condenser where aldehydes and by-products drop out this mixture is removed in a separator. The liquid stream from the separator contains appreciable amounts of dissolved gases, mainly propylene and propane. A product stripping column distills these out. The liquid stream from this stripper goes through two distillation columns in series that remove iso- and n-butyraldehyde as overhead products, respectively. A small stream that contains heavy by-products formed in the reactor leaves the bottom of the second column. This stream can be combined with the heavy ends stream from the n-butanol column and valuable aldehydes and alcohols recovered for recycle. The iso-butyraldehyde overhead product from the first aldehyde column may be hydrogenated and sold as a low cost solvent, cracked to synthesis gas and recycled to the oxo reactors, or burned as fuel. 

Strecker Aldehyde Formation. Formaldehyde, acetaldehyde and iso-butyraldehyde were formed by Strecker degradation of glycine, alanine and valine, respectively. Relative concentrations of aldehydes produced by microwave and conventional heating to comparable temperature is shown in Table I. Significantly higher concentrations were observed for microwave heated samples. 

The replacement of the pyrrolidine by morpholine, such as 5 versus 29 results in increased efficiency of the catalyst (Scheme 2.44) [31, 32]. Hindered aldehydes, such as 3,3-dimethylbutyraldehyde or iso-butyraldehyde are unreactive, however, under these conditions. 

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