N-Valeraldehyde

Raffinate-II typically consists of40 % 1-butene, 40 % 2-butene and 20 % butane isomers. [RhH(CO)(TPPTS)3] does not catalyze the hydroformylation of internal olefins, neither their isomerization to terminal alkenes. It follows, that in addition to the 20 % butane in the feed, the 2-butene content will not react either. Following separation of the aqueous catalyts phase and the organic phase of aldehydes, the latter is freed from dissolved 2-butene and butane with a counter flow of synthesis gas. The crude aldehyde mixture is fractionated to yield n-valeraldehyde (95 %) and isovaleraldehyde (5 %) which are then oxidized to valeric add. Esters of n-valeric acid are used as lubricants. Unreacted butenes (mostly 2-butene) are hydroformylated and hydrogenated in a high pressure cobalt-catalyzed process to a mixture of isomeric amyl alcohols, while the remaining unreactive components (mostly butane) are used for power generation. Production of valeraldehydes was 12.000 t in 1995 [8] and was expected to increase later. 

The 2003 ACGIH threshold limit valuetime-weighted average (TLV-TWA) for n-valeraldehyde is 50ppm (176mg/m ). 

The advantages of this new process are the high n/i ratio and the low formation of heavy ends (1.5%) and alcohols (1%) without any formation of formates. In the original cobalt-based high-pressure process the n/i ratio was 67/33, with substantial formation of heavy ends (6.7%), alcohols (6.6%) and pentylformates (4.2%).350 The n-valeraldehyde product is oxidized with molecular oxygen to n-valeric acid, the trimethylolpropane, pentaerythritol, or dipentaerythritol esters of which are used as lubricants.350... 

There are a number of reports in the literature on the photochemistry of amides, including the photodegradation of serum albumin,224 and of polypeptides.1 Photodegradation involves reactions of acyl and imine free radicals generated by photolytic scission of the amide group.23 33 The photooxidation of N-pentylhexanamide led to the formation of n-valeraldehyde and valeric acid from the amine part of the molecule... 

A further development of this successful technology was achieved to take advantage of the available feedstock base of butene isomers (raffinate II) for the preparation of n-C5 products (n-valeraldehyde, n-isoamyl alcohol, and n-valeric acid). In December 1995 production of n-valeraldehyde was started up in a new plant at Hoechst/Ruhrchemie (138). Generally, there are strong restrictions in the application of the two-phase catalytic processes to higher alkenes (Section IV.B.l), but the adaptation to butenes was possible with little modification of the process developed for propene. 

Kon, 109 Perkin, 108 n-Valeraldehyde, 322 n-Valeric acid, 354, 355,357,359,487 iso-Valeric acid, 354, 355 n-Valeronitrile, 408 Vanadium pentoxide catalyst, 463 Vapour pressure, 1, 2 of mixtures, 6-11 Veratraldehyde, 803, 804 Veratronitrile, 803, 804 Veronal, 1002, 1003 Vibro mixer, 65 Vinylacetio acid, 463, 465... 

When a 1% n-valeraldehyde solution of the Acac complex (III), plus varying amounts of TPP, were pressured to 2 Atm with a 1 to 1 mixture of H2/CO, the initial complex equilibria were about the same as those previously found in the aromatic solvent. As is shown by Figure 4, when the P/Rh ratio was 15, the dominant Rh compound at 35°C was the tris-TPP complex (I). At a P/Rh ratio of 6, the presumed dicarbonyl hydride (V) was the major complex. 

Fig. 12. 53. Experimental coverage-potential relation for n-valeraldehyde on platinum as a function of electrode potential. Two things should be noted First, adsorption-potential plots are roughly parabolic. Second, there is medium-good agreement between two entirely different methods, one based on the interpretation of ellipsometric data and the other on FTIR measurements. (Reprinted from J. O M. Bockris and K. T. Jeng, J. Electroanal-chem. 330 553, copyright 1992, with permission from Elsevier Science.)...

Conjugated diolefins react in an interesting fashion with synthesis gas. The major overall reaction consists of the hydrogenation of one double bond and the hydroformylation of the other. Thus, for example, butadiene gives n-valeraldehyde. The reaction may proceed by 1,4-hydrogen addition followed by isomerization and hydroformylation ... 

Fig. 5.3. Gas chromatogram of 2,4-dinitrophenylhydrazones of ten aliphatic aldehydes. Peaks 1 = formaldehyde 2 = acetaldehyde 3 = propionaldehyde 4 = acrolein 5 = isobutyraldehyde 6 = n-butyraldehyde 7 = isovaleraldehyde 8 = n-valeraldehyde 9 = crotonaldehyde 10 = n-capronaldehyde. For conditions see text. (Reproduced from / Chromatogr., 120 (1976) 379, by courtesy of Y. Hoshika.)...

The results of 3-methyl butanal photolysis in paraffinic solution - as well as in the vapour phase , also seem to indicate that the primary processes are the same as in the photolysis of -butyraldehyde. Isovaleraldehyde has six y-hydrogen atoms accordingly, the importance of primary process III is greater here than in the photolysis of n-butyraldehyde. The nature of the secondary reactions with isovaleraldehyde (and with n-valeraldehyde ) is analogous to that for n-butyr-aldehyde. 

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