Cyclopentadiene, oxidative

Some reports concerning the reaction of lithiated thioallylethers with oxiranes have been published. A slow reaction was observed with a terminal oxirane. However, with cyclopentadiene oxide, the reaction occured smoothly with an excellent regioselectivity in favor of the Sjv2 displacement in the ally lie position. Other examples involving sulfur, selenium and silicon stabilized organolithium reagents have been reported . 

Cyclohexadiene oxide (13) is even more reactive toward acid-catalyzed hydrolysis than cyclopentadiene oxide (12), and comparable yields of both 3-cyclohexene-trans-... 

The pH-independent reaction of cyclopentadiene oxide 12 in water is clearly different from that of 13.97 This reaction yields 33% of 3-cyclopentenone, 35% of cis-2,4-pentadienal and 35% of a mixture of cis and trans 1,2- and 1,4-diols (Scheme 28). When the reaction is carried out in D20 instead of H20, no deuterium is incorporated into the ketone product. Thus, 1,2-hydrogen migration is required for this reaction just as it is in the rearrangement of arene oxides to phenols. The mechanisms of product formation in this reaction are not fully understood. The observation that the diol mixture is similar to that from the acid-catalyzed hydrolysis of 12 suggests that an allylic carbocation may be involved in the diol-forming reaction. Ketone (96) and dienal (97) products are potentially formed either by stepwise or concerted mechanisms, and there is insufficient evidence to rule out either one. There is a significant normal salt effect on this pH-independent... 

The thioallyl anion from (132) reacts with cyclopentadiene oxide (133) in THF at -78°C to give (134 R1=2-PyrS,R2,R =bond) (62 ) which was transformed into the allyl alcohol (134 R R bond, R =0H) (713S) as part of a prostacyclin synthesis. ... 

Direct fluorination of aliphatics and non-C moieties Direct fluorination of benzenoid aromatics Direct fluorination of heterocyclic aromatics Oxidations of alcohols, diols and ketones with fluorine Photo-oxidation of a-terpinene and cyclopentadiene Oxidation of benzyl alcohol to benzaldehyde Homogeneously catalyzed oxidation of butyraldehyde Oxidation of sulfite to sulfate Photochlorination of aromatic isocyanates... 

The generic term azulene was first applied to the blue oils obtained by distillation, oxidation, or acid-treatment of many essential oils. These blue colours are usually due to the presence of either guaiazulene or velivazulene. The parent hydrocarbon is synthesized by dehydrogenation of a cyclopentanocycloheptanol or the condensation of cyclopentadiene with glutacondialdehyde anil. 

Cyclopentadiene (2.5) was prepared from its dimer (Merck-Schuchardt) immediately before use. Dimineralised water was distilled twice in a quartz distillation unit. Ethanol (Merck) was of the highest purity available. Acetonitrile (Janssen) was mn over basic aluminium oxide prior to use. 2,2,2-Trifluoroethanol (Acros) was purified by distillation (bp 79 - C). Co(N03)2 6H20,... 

Preparation. The industrial production of malonic acid is much less important than that of the malonates. Malonic acid is usually produced by acid saponification of malonates (9). Further methods which have been recendy investigated are the ozonolysis of cyclopentadiene [542-92-7] (10), the air oxidation of 1,3-propanediol [504-63-2] (11), or the use of microorganisms for converting nitriles into acids (12). 

Sulfur Polymer Cement. SPC has been proven effective in reducing leach rates of reactive heavy metals to the extent that some wastes can be managed solely as low level waste (LLW). When SPC is combined with mercury and lead oxides (both toxic metals), it interacts chemically to form mercury sulfide, HgS, and lead sulfide, PbS, both of which are insoluble in water. A dried sulfur residue from petroleum refining that contained 600-ppm vanadium (a carcinogen) was chemically modified using dicyclopentadiene and oligomer of cyclopentadiene and used to make SC (58). This material was examined by the California Department of Health Services (Cal EPA) and the leachable level of vanadium had been reduced to 8.3 ppm, well below the soluble threshold limit concentration of 24 ppm (59). 

Oxidation. Cyclopentadiene reacts spontaneously with oxygen to form brown, gummy products that usually contain substantial amounts of... 

Cyclopentadiene has also been oxidized by singlet oxygen to 4,5-epoxypenten-2-al-l, cis and trans isomers. These compounds and their hydrogenated diol products are claimed as useful intermediates as cross-linking agents, and in the production of pesticides and perfumes (34). 

Few isothiazoles undergo simple cycloaddition reactions. 4-Nitroisothiazoles add to alkynes (see Section 4.17.7.4). With 5-thiones (84) and dimethyl acetylenedicarboxylate, addition to both sulfur atoms leads to 1,3-dithioles (85) (77SST(4)339, 80H(14)785, 81H(16)156, 81H(16)595). Isothiazol-3-one 1-oxide and the corresponding 1,1-dioxide give normal adducts with cyclopentadiene and anthracene (80MI41700), and saccharin forms simple 1 1 or 1 2 adducts with dimethyl acetylenedicarboxylate (72IJC(B)881). 

Methylene thiirane is obtained by thermolysis of several spirothiirane derivatives which are formally Diels-Alder adducts of methylenethiirane and cyclopentadiene or anthracene <78JA7436). They were prepared via lithio-2-(methylthio)-l,3-oxazolines (c/. Scheme 121). A novel synthesis of the allene episulfide derivatives, 2-isopropylidene-3,3- dimethylthiirane (good yield) or its 5-oxide (poor yield), involves irradiation of 2,2,3,3-tetramethyl-cyclopropanethione or its 5-oxide (81AG293). Substituents on the thiirane ring may be modified to give new thiiranes (Section 5.06.3.9). The synthesis of thiirane 1-oxides and thiirane 1,1-dioxides by oxidation is discussed in Section 5.06.3.3.8 and the synthesis of 5-alkylthiiranium salts by alkylation of thiiranes is discussed in Section 5.06.3.3.4. Thiirene 1-oxides and 1,1-dioxides may be obtained by dehydrohalogenation of 2-halothiirane 1-oxides and 1,1-dioxides (Section 5.06.4.1.2). 

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. 

Tropolone has been made from 1,2-cycloheptanedione by bromination and reduction, and by reaction with A -bromosuccinimide from cyolo-heptanone by bromination, hydrolysis, and reduction from diethyl pimelate by acyloin condensation and bromination from cyclo-heptatriene by permanganate oxidation from 3,5-dihydroxybenzoic acid by a multistep synthesis from 2,3-dimethoxybenzoic acid by a multistep synthesis from tropone by chlorination and hydrolysis, by amination with hydrazine and hydrolysis, or by photooxidation followed by reduction with thiourea from cyclopentadiene and tetra-fluoroethylene and from cyclopentadiene and dichloroketene. - ... 

Metal-vapor synthesis also prepares metallaboranes and metallacarboranes with oxidation of the metal. Thermally generated Ni, Co and Fe atoms react with the nido-carborane 2,6-C2B7H, and either cyclopentadiene, toluene, mesitylene, or... 

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