Heptenes, from oxidation

SAP catalysts have also been applied in the Wacker oxidation584 of higher olefins where the separation of products from the catalyst is cumbersome. Palladium(II) and copper(II) salts immobilized on controlled pore glass CPG-240 in the presence of water catalysed the oxidation of 1-heptene to 2-heptanone in conversions up to 24%.585 Significant isomerization to 2-heptene and 3-heptene (isomerization/oxidation=2/3) was also observed. However, an advantage of SAP-Wacker oxidation catalysts over classical systems is that the Cu(II) is confined to the support and therefore not corrosive whereas aqueous Cu2+ is very corrosive to steel. 

B.8 Batch Production of L-Phenylalanine and L-Aspartic Acid. Unit 900 B.9 Acrylic Acid Production via the Catalytic Partial Oxidation of Propylene B.IO Production of Acetone via the Dehydrogenation of Isopropyl Alcohol B.ll Production of Heptenes from Propylene and Butenes... 

The enol ether double bond contained within the ds-fused dioxa-bicyclo[3.2.0]heptene photoadducts can also be oxidized, in a completely diastereoselective fashion, with mCPBA. Treatment of intermediate XXII, derived in one step from a Patemo-Buchi reaction between 3,4-dimethylfuran and benzaldehyde, with mCPBA results in the formation of intermediate XXIII. Once again, consecutive photocycloaddition and oxidation reactions furnish a highly oxygenated system that possesses five contiguous stereocenters, one of which is quaternary. Intermediate XXIII is particularly interesting because its constitution and its relative stereochemical relationships bear close homology to a portion of a natural product known as asteltoxin. 

FIGURE 6.28 Oxidation of squalene to 6-methyl-5-hepten-2-one, acetone, geranyl acetone, and 4-oxopentanal (adapted from Fruekilde et al., f998). 

Oxametallacycles are prepared from unsaturated aldehydes or ketones. Oxidative cyclization of 6-hepten-2-one (312) catalysed by the Ti catalyst Cp2Ti to give cyclopentanol 315 has been developed. The key step is the cleavage of the strong Ti—O bond in the oxametallacycle 313 with oxophilic hydrosilane, and the silyl ether 314 is formed with regeneration of Cp2Ti [129,130], Cyclization of 5-hexenal (316)... 

The alkadienals could be formed from the autoxidation of PUFA and may contribute desirable arenas to freshly prepared foods (19). Further degradation of alkadienals often increased undesirable flavors. Josephson and Lindsay demonstrated that 2,4-decadienal could produce 2-octenal and ethanal (20) and 2,6-nonadienal could produce 4-heptenal and ethanal (21) via retro-aldol condensation mechanisms. Hsieh et al. (22) reported that iscmers of various alkadienals and alkatrienals gave green, greasy and oxidized fish oil odors in crude menhaden fish oil. 

Controlled oxidation of a primary alcohol with a mixture of sulfuric and chromic acids gives the corresponding aldehyde. In the preparation of low-molecular-weight aldehydes, an aqueous medium is used and the product is removed by steam distillation, thus preventing further oxidation. This procedure is well illustrated by the preparation of propion-aldehyde (49%) and isovaleraldehyde (60%). Certain benzyl alcohols are dissolved in aqueous acetic acid for chromic acid oxidation. Ole-finic aldehydes are produced by a rapid low-temperature (5-20°) oxidative procedure, as illustrated by the preparation of 2-heptenal (75%) from 2-heptenol. Aldehyde ethers such as methoxyacetaldehyde and ethoxy-acetaldehyde have been prepared by the chromic acid oxidation of the corresponding alcohols in 17% and 10% yields, respectively. ... 

The literature of this reaction to 1940 has been adequately reviewed. The emphasis up to that time was placed on obtaining higher yields of carbonyl compounds by hydrolysis of the ozonides. Several methods have been described for the oxidative cleavage of ozonides to acids. These procedures may prove valuable in the synthesis of certain acids. By adding the ozonide of 1-tridecene to an alkaline silver oxide suspension at 95°, a 94% yield of lauric acid is obtained. Decomposition of ozonides with 30% hydrogen peroxide is described for the preparation of 5-methyl-hexanoic acid (67%) from 6-methyl-l-heptene and of adipic acid (60%) from cyclohexene. A study of solvents for ozonolysis has been made. ... 

Flavors and aromas commonly associated with seafoods have been intensively investigated in the past forty years ( l-7), but the chemical basis of these flavors has proven elusive and difficult to establish. Oxidized fish oils can be described as painty, rancid or cod-liver-oil like (j ), and certain volatile carbonyls arising from the autoxidation of polyunsaturated fatty acids have emerged as the principal contributors to this type of fish-like aroma ( 3, 5, 9-10). Since oxidized butterfat (9, 11-12) and oxidized soybean and linseed oils (13) also can develop similar painty, fish-like aromas, confusion has arisen over the compounds and processes that lead to fish-like aromas. Some have believed that the aromas of fish simply result from the random autoxidation of the polyunsaturated fatty acids of fish lipids (14-17). This view has often been retained because no single compound appears to exhibit an unmistakable fish aroma. Still, evidence has been developed which indicates that a relatively complex mixture of autoxidatively-derived volatiles, including the 2,4-heptadienals, the 2,4-decadienals, and the 2,4,7-decatrienals together elicit unmistakable, oxidized fish-oil aromas (3, 9, 18). Additionally, reports also suggest that contributions from (Z -4-heptenal may add characteristic notes to the cold-store flavor of certain fish, especially cod (4-5). 

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