System isobutyraldehyde

J. G. WOJTASINSKI. J. Chem. Eng. Data, 1963 (July), pp. 381-385. Measurement of total pressures for determining liquid-vapour equilibrium relations of the binary system isobutyraldehyde-n-butyraldehyde. 

An example of such recychng 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 ra- and isobutyraldehydes using a cobalt-based catalyst. Two parallel reactions occur ... 

Domling et al. made react (3-amino butyric thioacid, 89, the isobutyraldehyde 64, and 86 into the product 90, which simultaneously contains a 13-lactam group and a thiazole system. 

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. 

The existence of the enamine intermediate of proline-catalyzed reaction with acetone as a donor was detected by mass analysis [54], but not by aH NMR. The formation of the presumed enamine intermediate generated from pyrrolidine-acetic acid and isobutyraldehyde was confirmed by 1H NMR [29a]. In this study, the enamine formation in the presence of pyrrolidine-acetic acid was observed within 5 min, but the enamine was shown to form only very slowly in the absence of acid. In these pyrrolidine derivative-acid combination catalysts, the acid component was shown to be important both for faster enamine formation and for the stereocontrol in the C-C bond-forming step. These catalyst systems are essentially split-proline systems that allow for the contributions of the pyrrolidine and carboxylate functionalities of proline to be probed independently. 

The best result using aldehyde/oxygen was reported recently by Qi et al. [53] using novel Ru(HL)(L)C12 (HL is N-2 chlorophenyl-2-pyridine-carboxamide) complexes and isobutyraldehyde/oxygen for the epoxidation of cycbc alkenes. The turnover frequencies (TOFs) in this system were as high as 350 h 1 for cyclohexene, with a selectivity towards the epoxide of 87% (see Eq. 12). 

In terms of practicality, molecular oxygen is a very attractive terminal oxidant. In this arena, a novel 7V-2 -chlorophenyl-2-pyridinecarboxamide ruthenium complex 29 has been reported to catalyze the efficient epoxidation of cyclic alkenes in the presence of 1 atm of oxygen and isobutyraldehyde, which is believed to coordinate to the catalyst and prevent the formation of unwanted allylic oxidation products. Using this system, cyclooctene 30 is converted to the corresponding epoxide in excellent yield in 9 h at ambient temperature. Interestingly, the reaction is shut down by the addition of 2,6-di-/er/-butyl-4-methylphenol, so that a i ical mechanistic pathway has been postulated <03CC1058>. 

The use of alkali metal oxide catalysts for aldol condensation reactions has been examined for the production of 2-ethylhexenal from butanal [34]. When coupled to a hydrogenation catalyst the system can produce the plasticizer alcohol 2-ethyl-hexanol directly. When isobutyraldehyde was used as the feed to a silica-supported sodium oxide catalyst, no products were formed but a significant amount of carbon was deposited on the catalyst and in the reactor (Scheme 21.2). 

One of the most efficient enzymatic systems that generates triplet state acetone is the horse radish peroxidase(HRP)-catalyzed oxygenation of isobutyraldehyde (Eq. 79). Related enzymatic processes include the autoxidation of linear carbox-aldehydes, malonaldehyde, a-formylphenylacetic acid, indole-3-acetal-dehyde, indole-3-pyruvic acid, ° and indole-3-acetaldehyde. Consequently, there is no question about the existence of enzymatically generated electronic excitation in the cell however, what do these excited states do in the biological system ... 

In systems where the hydroxyl is on a secondary or tertiary carbon, neighboring hydroxyl participation can occur. For example, the acid hydrolysis of I-chloro-2-methyl-propan-2-ol gives isobutyraldehyde as well as isobutylene glycol (i8). 

H-Mordenite catalyzes the smooth conversion of simple aldehydes and alcohols to form acetals at 30° in the liquid phase. From the examples in Table XXVII, it is apparent that in these heterogeneous catalytic systems, acetal formation is dependent on the structures of both the aldehyde and the alcohol involved. Thus, for a given aldehyde, yields of acetal decreased in the order primary > secondary > tertiary that is, branching at the a-carbon of the alcohol reduced the equilibrium conversion to acetal. In the isobutyraldehyde reactions, an extremely sharp drop in conversion was observed upon changing from isopropanol to fert-butanol as reactant. This observation suggests that, in addition to the increased steric interactions between organic reactants encountered in the tert alcohol system, molecular sieving-type interactions within the narrow mordenite pore system are operative. 

When dimethyl l-(trimethylsilyl)benzylphosphonate is treated with benzaldehyde in the presence of a fluoride ion source (CsF, KF, or TBAF), stilbene and dimethyl benzylphosphonate, a protodesilylation product, are produced. The best yield of stilbene (85%) is obtained on heating in THF for 1 day with freshly dried CsF. Use of MeCN gives a similar result, whereas in toluene the reaction becomes very slow. KF is less effective even in the presence of 18-crown-6 ether. TBAF is efficient at room temperature however, the yield seems to be modest because of difficulty in drying "0 or the existence of acidic hydrogen, easily transmetallated by the resulting carbanion. When CsF or KF is used, only ( )-stilbene is obtained, whereas TBAF afforded a mixture of (Eland (Z)-stilbene in a 90/10 ratio. The formation of dimethyl benzylphosphonate seems to result from protonation by water that still remained in the system, and the yield of the olefin becomes water dependent. In the case of the reaction with isobutyraldehyde, the corresponding olefin is obtained in low yield (35%) as an mixture (70/30). By contrast, cinnamaldehyde gives... 

The system was very sensitive to the transition metal ion added to the platinum. When it was nickel, hydrocin-namaldehyde was obtained in 97% selectivity.75 The intermediates in these reductions are probably metal hydride clusters. When the colloidal platinum is supported on magnesium oxide, without another transition metal, the reduction produces the unsaturated alcohol with 97% selectivity.76 A rhodium colloid stabilized by the same polymer was used with a water-soluble phosphine in the hydro-formylation of propylene to produce 1 1 mixture of /r-bu-tyraldehyde and isobutyraldehyde in 99% yield.77 It could be used at least seven times, as long as it was not exposed to air. 

IB-MA and ID-MA copolymers (3.0g) were combined with 0.1N hydrochloric acid (80ml). The polymer suspensions were stirred and heated for 12 hr. at 50°C and A hr. at 70°C. Isobutyraldehyde odor was detected coming from the IB-MA system. The polymers were collected, washed with deionized water and dried in vacuo over phosphorus pentoxide at room temperature to obtain slightly yellow colored materials soluble in DMF and DMSO. The IR spectrum of each copolymer exhibited absorptions at 3350, 2650, 1760 (with a shoulder at 1720-1700), 1630, 1165 and 1120 cm-1, with no anhydride absorptions at 1855 and 1775 cm-1 and no cyclic acetal absorptions in the 1200-1000 cm-1 region. The 13C NMR spectra, though not well resolved, clearly showed no methyl protons for the recovered IB-MA and ID-MA copolymers. 

Metal phthalocyanines have been found to catalyze the oxidation of sulphides to sulphones at room temperature by molecular oxygen (1 atm) in the presence of isobutyraldehyde as sacrificial aldehyde. Among the metal phthalocyanines studied those of Fe(II), Mn(II) and Co(II)tetrasulphonato- showed excellent activity, followed by VO, while those of Ni(II) and Cu(II) were found to be least active for sulfide oxidation. Mn(II)phthalocyanine catalyzed epoxidation of olefins with molecular oxygen -isobutyraldehyde systems is also reported. 

In continuation to our studies with molecular oxygen as the primary oxidant[8], we now report metal phthalocynanine catalyzed oxidation of sulphides to sulphones and olefins to epoxides by dioxygen-isobutyraldehyde system under ambient conditions (Scheme-1). 

Sulphide Oxidation by Molecular Oxygen - Isobutyraldehyde System in... 

Oxidation of Olefins with Molecular Oxygen - Isobutyraldehyde Systems in Presence Mn(II)Pc... 

The mechanism of metal phthalocyanine catalysed oxidation by molecular oxygen -isobutyraldehyde system is not established at this stage. The iron[14], manganese[15] and cobalt tetrasulphonato-[16] phthalocyanines are known to form superoxo complexes with dioxygen and are known to catalyse autoxidation reactions[13]- The acyl radical formation thus can be initiated by interaction of metal phthalocyanine-dioxygen superoxo complex with isobutyraldehyde. The acyl radical in presence of oxygen can yield acylperoxy radical or peracid as the oxidising speceis[17]. 

Chocarom Pyrazine isomers were isolated from the skin and flesh of potato Solanum tuberosum L.) cultivars after baking 4). 3,5-Dimethyl-2-isobutylpyrazine [2,5-dimethyl-3-(2-methylpropyl)-pyrazine] was isolated by Oruna-Concha, Craig, Duckham and Ames from the following potato cultivars - Cara, Nadine, Flanna and Marfona. 3,6-Dimethyl-2-isobutyl-pyrazine [3,5-dimethyl-2-(2-methylpropyl)pyrazine], was found by the same team in Cara and Marfona potato cultivars. 2,5-Dimethyl-3-isobutylpyrazine was also detected by Welty, Marshall and Grun in chocolate ice cream prepared from cocoa flavor (5). Both pyrazines were also found as key odorant compounds in dark chocolate by Counet, Callemien, Ouwerx and Collin (6). The role of amino acids in alkyl-substituted pyrazines formation in model systems containing pyruvaldehyde was examined by Mea (7). 2,5-Dimethyl-3-isobutylpyrazine was formed in the model system with valine. Both isomers were prepared synthetically by Chen (S) by reacting acetol, isobutyraldehyde and ammonium acetate, with low yield of 22.3%. Subsequent proprietary work by the author has improved the yield to 65%. 

Not only does the solvent affect the reaction rate, but it also determines the reaction mechanism. In Starks extraction mechanism of PTC, most reacting compound transfers to the bulk phase. However, reaction may occur at the interface of the two phases. For example hexachlorocyclotriphosphazene has been reported to react very slowly with 2,2,2-trifluoroethanol in an alkaline solution of NaOH/C HjCl two-phase system in the absence of phase-transfer catalyst.Since sodium 2,2,2-trifluoroe anoxide is not soluble in chlorobenzene, the process probably proceeds at the interface region of the system. Similar is the reaction of benzylation of isobutyraldehyde in the presence of tetra-n-butylammonium iodide in an alkaline solution of NaOH/toluene, which is a two-phase system. Makosza interfacial mechanism was employed to rationalize the experimental results. The main reason is that the ammonium salt of the nucleophilic reagent is not soluble in toluene. 

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