Iso-valeraldehyde

The hydroformylation of conjugated dienes with unmodified cobalt catalysts is slow, since the insertion reaction of the diene generates an tj3-cobalt complex by hydride addition at a terminal carbon (equation 10).5 The stable -cobalt complex does not undergo facile CO insertion. Low yields of a mixture of n- and iso-valeraldehyde are obtained. The use of phosphine-modified rhodium catalysts gives a complex mixture of Cs monoaldehydes (58%) and C6 dialdehydes (42%). A mixture of mono- and di-aldehydes are also obtained from 1,3- and 1,4-cyclohexadienes with a modified rhodium catalyst (equation ll).29 The 3-cyclohexenecarbaldehyde, an intermediate in the hydrocarbonylation of both 1,3- and 1,4-cyclo-hexadiene, is converted in 73% yield, to the same mixture of dialdehydes (cis.trans = 35 65) as is produced from either diene. 

According to Table V the tolerable limits of iso-valeraldehyde concentration seem to be variety dependent while "Rubika" containing 1.8 ppm isovaleralde-hyde does not exhibit distinct undesirable flavor changes, "Rubin" having the same isovaleraldehyde concentration and "Pariser Markt" with an even lower amount of isovaleraldehyde already show a burnt flavor character. These findings may be attributed to the fact that... 

Virtually all of the six-carbon aldehydes and alcohols found in freshly cooked pumpkin have been lost. Furfural has increased significantly and 2-methyl tetra-hydrofuran-3-one has appeared. These changes are likely due to the severe thermal processing canned pumpkins must receive. Pumpkins are a low acid food which heat primarily by conduction and as such require extended processing times at 250°F or higher. Furfural is a well known constituent of thermally decomposed carbohydrates, and the furanone as well as the furyl-ketone have been reported in numerous cooked food products (10). 2-Methyl butanal and iso valeraldehyde are also craranon constituents of pro-... 

Metallated methylenecyclobutane has been used as an isoprene equivalent in terpene synthesis. Methylenecyclobutene has been metallated with butyl-lithium and tetramethylethylenediamine. Reaction of the ambident anion (384) with electrophiles gives a mixture of positional isomers. The ratio of the isomers can be controlled by variation of solvent and temperature in this reaction and the cyclobutene ring in the products can then be opened thermally to dienes. This method has been applied to a synthesis of a component of the Ips confusus pheromone. Reaction of (384) with iso-valeraldehyde gave 30 % of the cyclobutene (385) which was isomerized to (386) by heating at 150°C. 

Bamford CH, Norrish RGW (1935) Primary photochemical reactions. Part VII. Photochemical decomposition of iso-valeraldehyde and di-n-propyl ketone. J Chem Soc 1504—1511... 

Surprisingly the Q-monoaldehyde fraction contained more than 96% n-valeraldehyde and only 4% of iso-valeraldehyde. 

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