2- -2-cyclopentene-1 acetaldehyde

Oxidative cleavage of bicyclic alcohols. Oxidation of either exo- or endo-norbornanol (1) with 2 equiv. of ceric ammonium nitrate in 50% aqueous acetonitrile at 50° gives three products of oxidative cleavage, 3- and 4-cyclopentene-acetaldehydes (2) and (3) and 3-nitratocyclopentaneacetaldehyde (4).3 Oxidation... 

Dehydrogenation processes in particular have been studied, with conversions in most cases well beyond thermodynamic equihbrium Ethane to ethylene, propane to propylene, water-gas shirt reaction CO -I- H9O CO9 + H9, ethylbenzene to styrene, cyclohexane to benzene, and others. Some hydrogenations and oxidations also show improvement in yields in the presence of catalytic membranes, although it is not obvious why the yields should be better since no separation is involved hydrogenation of nitrobenzene to aniline, of cyclopentadiene to cyclopentene, of furfural to furfuryl alcohol, and so on oxidation of ethylene to acetaldehyde, of methanol to formaldehyde, and so on. 

The results of the olefin oxidation catalyzed by 19, 57, and 59-62 are summarized in Tables VI-VIII. Table VI shows that linear terminal olefins are selectively oxidized to 2-ketones, whereas cyclic olefins (cyclohexene and norbomene) are selectively oxidized to epoxides. Cyclopentene shows exceptional behavior, it is oxidized exclusively to cyclopentanone without any production of epoxypentane. This exception would be brought about by the more restrained and planar pen-tene ring, compared with other larger cyclic nonplanar olefins in Table VI, but the exact reason is not yet known. Linear inner olefin, 2-octene, is oxidized to both 2- and 3-octanones. 2-Methyl-2-butene is oxidized to 3-methyl-2-butanone, while ethyl vinyl ether is oxidized to acetaldehyde and ethyl alcohol. These products were identified by NMR, but could not be quantitatively determined because of the existence of overlapping small peaks in the GC chart. The last reaction corresponds to oxidative hydrolysis of ethyl vinyl ether. Those olefins having bulky (a-methylstyrene, j8-methylstyrene, and allylbenzene) or electon-withdrawing substituents (1-bromo-l-propene, 1-chloro-l-pro-pene, fumalonitrile, acrylonitrile, and methylacrylate) are not oxidized. 

Acetaldehyde diethyl acetyl (acetyl) Cumene (isopropylbenzene) Cyclohexane Cyclopentene... 

Intramolecular phosphonate-based olefination has been used to construct five-membered rings in a number of syntheses for example in a novel approach to [3.3.0] fused pyrazolidinones (244) (Scheme 35), a totally synthetic class of antibacterial agents. 44 new, convergent synthesis of the fungal metabolite and useful synthetic intermediate (+)-terrein (248) has been reported. 45 The method is based on two phosphonate olefination steps. The diphosphonate (245), obtained from L-tartaric acid, gives, on treatment with base, a mixture of the required phosphonate (24 6) and the diphosphonate (247). However, under appropriate conditions (246) is the major product and can be converted into (+)-terrein by reaction with acetaldehyde (Scheme 36). Olefination of the ketone (249) with dimethyl diazomethylphosphonate (250) provides, via carbene insertion, the cyclopentene (251) and hence a new route to (-)-frontalin (252) (Scheme 37).146... 

Figure 5.2.10. Cellulose pyrolysate obtained at 59CP C by Py-GC/MS. The separation was done on a Carbowax type column. 1 CO2, 2 acetaldehyde, 3 acetone, 4 2-butanone, 5 2,3-butandione, 6 toluene, 7 water, 8 cyclopentanone, 9 methylfuran, 10 3-hydroxy-2-butanone, 11 hydroxypropanone, 12 cyclopent-1-en-2-one, 13 2-methylcyclopentenone, 14 acetic acid, 15 acetic acid anhydride, 16 furancarboxaldehyde, 17 methylcyclopentenone, 18 dimethylcyclopentenone, 19 5-methylfurancarboxaldehyde, 20 2,3-dihydro-2-furanone, 21 furan-2-methanol, 22 3-methylfuran-2-one, 23 2(5H)-furanone, 24 hydroxycyclopentenone, 25 3,5-dimethylcyclopentan-1,2-dione, 26 2-hydroxy-3-methyl-2-cyclopenten-1-one, 27 2-hydroxy-3-ethyl-2-cyclopenten-1-one, 28 2,3-dimethyl-2-cyclopenten-1-one, 29 phenol, 30 dimethylphenol, 31 3 thyl-2,4(3H,5H)-furandione, 32 3-butenoic acid, 33 1,4 3,6-dianhydro-a-D-glucopyranose, 34 5-(hydroxymethyl)-furfural.

An example of a DHS application is the determination of aroma-active compounds in bambuu shoots. In this study, compoimds such as p-cresol, methional, 2-heptanoI, acetic acid, ( ,Z)-2,6-nonadienal, linalool, phenyl acetaldehyde, were extracted from the bambuu shoot samples and analysed by GC. The required sample amount was 10 g, and the extraction temperature was 60°C, using a 30 min extraction time. The stripped analytes were first trapped into a cooled adsorbent tube (VOCARB 3000, at 0 °C), and then thermally desorbed to GC. In DTD, the sample amount required for the analysis is typically smaller than in solid head-space (SHS). In the determination volatile components such as camphor, 1,8-cineoIe and 2,3,S,S-tetramethyl-4-methylene-2-cyclopenten-l-one, from Lavandula luisieri, only 10-20 mg of (dry) plant sample was required for the analysis. The volatiles were desorbed fi om the sample under a helium flow and then cryofocused on a Tenax TA trap at -30 °C. The trap was then quickly heated and the desorbed volatiles were transferred directly to the GC column through a heated fused-silica line (85). 

Acetaldehyde Benzyl alcohol 2-Butanol dioxanes Chlorofluoroethylene Cyclohexene 2-Cyclohexen-1 -o1 Cyclopentene... 

Methyl n-amyl ketone Methyl anthranilate Methyl benzoate a-Methylbenzyl acetate a-Methylbenzyl alcohol Methyl cinnamate 3-Methyl-2-cyclopenten-2-ol-1-one 6-Methyl-3,5-heptadien-2-one Methyl a-ionone Methyl isoeuqenol Methyl laurate 1-Methyl-1-methoxycyclododecane Methyl 2-nonenoate Methyl nonyl acetaldehyde Methyl 2-octynoate Methyl pelarqonate Methyl phenylacetate Methyl salicylate Methyl tiqiate Methylundecanal dimethyl acetal Myrcene Nerol... 

High conversions of cyclopentene were obtained by Nuetzel et al. [59] with hydroperoxides, inorganic peroxides, or aromatic nitroderivatives. To increase the stability of some tungsten-based catalytic systems, Witte et al. [63] employed a-halogenated alcohols such as chloroethanol, 2-chlorocyclohexanol, bro-moethanol, l,3-dichloro-2-isopropanol, o-chlorophe-nol, and 2-iodocyclohexanol. It was observed that methyl and ethyl acetals of formaldehyde, acetaldehyde, chloroform, and benzaldehyde impart good staiblity to the binary systems of tungsten, whereas epoxides such as ethylene oxide and butylene oxide lead at the same time to an increase in activity and stability. 

This dihydride thermally or photochemically reductively eliminates hydrogen to complete the catalytic cycle. In a similar manner, [Pt2(pop)4] is a photochemical catalyst for the conversion of ethyl alcohol to acetaldehyde and hydrogen, and also for the transfer hydrogenation of cyclohexene and cyclopentene with isopropyl alcohol ... 

H2, CO, CO2, H2O, furan, fiirancarboxyaldehyde, methyUurans, acetone, hydroxypropanone, butenal, butanone, butanedione, levoglucosan Fixed gases (not identified), pentene, acetaldehyde, furan, propionaldehyde, acetone, acrolein, 2-methyUuran, butyraldehyde, methyl ethyl ketone, benzene, 2,5-dimethylfiiran, methyl vinyl ketone, 2,3-butanedione, toluene, crotonaldehyde, H2O, cyclopentanone, cyclooctatetraene, acetol, pyruvaldehyde, acetic add, furfural, formic acid, 5-methyl-2-furfural, furfuryl alcohol, butyrolactone, 2-hydroxy-3-methyl-3-cyclopenten-2-one, phenol, o-cresol, m-cresol, p-cresol, 2,5-dimethylphenol, 3,4-diinetfaylphenol, 5-hydroxymefhylfuifural Mainly H2O and CO 2, smaller amounts of CO, formaldehyde, methanol, acetic acid, ethanol and acetaldehyde, and very htUe tar Product fraction volatile at 25°C contains acetic acid, CO2, CO, CH4,... 

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