Vinyl chloride, cyclopropanation

Marvel, Sample, and Roy concluded that cyclopropane rings were formed when a dilute solution of poly-(vinyl chloride) in dioxane was treated with zinc, which removes halogen atoms from alternate carbon atoms. Only 84 to 86 percent of the chlorine could be removed, however, a result which was attributed to the occasional isolation of a lone substituent between reacted neighbors. The structure of the product was presumed to be... 

The best-known gas hydrates are those of ethane, ethylene, propane, and isobulaue. Others include methane and I butene, most of the fluorocarbon refrigerant gases, nitrous oxide, acetylene, vinyl chloride, carbon dioxide, methyl and ethyl chloride, methyl and ethyl bromide, cyclopropane, hydrogen sulfide, methyl mercaptan, and sulfur dioxide. 

Generation of Alkyl and Cycloalkyl Carbenes - Photolysis or thermolysis of a series of alkylchlorodiazirines (16) (Scheme 7) in the presence of alkenes, such as tetramethylethene, results in 1,2-H shifts, giving the corresponding vinyl chorides (18), in competition with additions of the carbenes (17) to the alkenes, yielding cyclopropanes (19). The mechanism of these reactions is discussed in the light of results obtained from photoacoustic calorimetry, and the ratio of vinyl chloride to cyclopropane seems to depend on the excited states of the carbene precursors and also on carbene-alkene complexes. Similar reactions of related diazirines have been investigated by flash photolysis. 

The copper-catalysed decomposition of bisdiazoketones has been developed into a synthesis of seven-membered rings for example, treatment of 1,7-bisdiazoheptane-2,6-dione and l,7-bisdiazo-4-chloroheptane-2,6-dione with copper bis(acetylace-tonate) in benzene gave cyclohept-2-ene-l,4-dione and 6-chlorocyclohept-2-ene-l,4-dione respectively the latter gave y-tropolone when treated with triethylamine. Treatment of the vinylic chloride (21) with n-butyl-lithium gave bicyclic methylene cyclopropane (22) which could be reduced selectively at the C-5—double bond by di-imide. ... 

D Acetone, ammonia, benzene, butane, cyclopropane, ethanol, gasoline, hexane, methanol, methane, vinyl chloride, natural gas, naphtha, propane, or gases of equivalent hazard. ... 

A cornerstone of the chemistry of polymers is a publication on the structure of poly(vinyl chloride) by Marvel and coworkers [42]. This paper, which is still cited, established the head-to-tail structure of PVC. The approach used involved the dechlorination of uncross-linked poly(vinyl chloride) in dioxane solution with zinc. From statistical considerations, it had been predicted that random attack by zinc on the polymer chains should produce different degrees of dehalogenation depending on whether the polymer were of a head-to-tail or a head-to-head, tail-to-tail structure. Since the experiment resulted in the removal of 84-87of the available chlorine, as predicted, and the resultant product consisted of polymeric cyclopropane units with occasional, isolated... 

However, the formation of cyclic anhydrides leaves several carboxylic groups isolated these groups have no option but to react intermolecularly to generate cross-links. A similar phenomenon is observed in the dechlorination reaction of poly(vinyl chloride) by zinc powder with the formation of cyclopropane cycles from 1,3-dichloro-type sequences (regular dyads) ... 

Cyclopropanation of Vinyl Chloride Another demonstration of substrate-controlled asymmetric halogen-ations is found in Evans et al. s synthesis of callipeltoside A... 

Epoxidation of aldehydes and ketones is the most profound utility of the Corey-Chaykovsky reaction. As noted in section 1.1.1, for an a,P-unsaturated carbonyl compound, 1 adds preferentially to the olefin to provide the cyclopropane derivative. On the other hand, the more reactive 2 generally undergoes the methylene transfer to the carbonyl, giving rise to the corresponding epoxide. For instance, treatment of P-ionone (26) with 2, derived from trimethylsulfonium chloride and NaOH in the presence of a phase-transfer catalyst Et4BnNCl, gave rise to vinyl epoxide 27 exclusively. ... 

Photolysis of the sulphinyl-3H-pyrazole 587 in ether or methylene chloride leads to the formation of a relatively stable carbene 588 that can be identified by physical methods. When the irradiation is performed in ethyl vinyl ether or in furan, the expected cyclopropanes are formed smoothly and stereospecifically683 (equation 374). 

ETHYLENE GLYCOL ETHYL MERCAPTAN DIMETHYL SULPHIDE ETHYL AMINE DIMETHYL AMIDE MONOETHANOLAMINE ETHYLENEDIAMINE ACRYLONITRILE PROPADIENE METHYL ACETYLENE ACROLEIN ACRYLIC ACID VINYL FORMATE ALLYL CHLORIDE 1 2 3-TRICHLOROPROPANE PROPIONITRILE CYCLOPROPANE PROPYLENE 1 2-DICHLOROPROPANE ACETONE ALLYL ALCOHOL PROPIONALDEHYDE PROPYLENE OXIDE VINYL METHYL ETHER PROPIONIC ACID ETHYL FORMATE METHYL ACETATE PROPYL CHLORIDE ISOPROPYL CHLORIDE PROPANE... 

The reactions of benzothiazinium salt 87d with nucleophiles such as PhSNa, PhSeNa, and KCl were examined (see Equation (24) and Table 13) <1997J(P1)309>. Treatment of 87d with PhSNa at 0°C for 2h provided vinyl cyclopropane 88d (82%) as the major product together with ring-opened product 90a (11%) (see entry 1). When the reaction was carried out with PhSeNa at —20 °C, and then warmed to room temperature, 90b was obtained in a higher yield (94%) with only trace of 88d being formed (see entry 2). Allyl chloride 90c was exclusively furnished by treatment of 87d with KCl in acetone at room temperature for 12 h (see entry 3). 

The formation of cyclopropanes from 7C-deficient alkenes via an initial Michael-type reaction followed by nucleophilic ring closure of the intermediate anion (Scheme 6.26, see also Section 7.3), is catalysed by the addition of quaternary ammonium phase-transfer catalysts [46,47] which affect the stereochemistry of the ring closure (see Chapter 12). For example, equal amounts of (4) and (5) (X1, X2 = CN) are produced in the presence of benzyltriethylammonium chloride, whereas compound (4) predominates in the absence of the catalyst. In contrast, a,p-unsatu-rated ketones or esters and a-chloroacetic esters [e.g. 48] produce the cyclopropanes (6) (Scheme 6.27) stereoselectively under phase-transfer catalysed conditions and in the absence of the catalyst. Phenyl vinyl sulphone reacts with a-chloroacetonitriles to give the non-cyclized Michael adducts (80%) to the almost complete exclusion of the cyclopropanes. 

Cyclopentanes, synthesis, 66, 10 CYCLOPEKTANONE SYNTHESIS, 66, 87, 92, 93 Cyclopentanone, 2-carbomethoxy-3-vinyl, 66, 56 Cyclopentanone, 2-ethenyl-2-methyl (88729-76-4), 66, 94 2-CYCLOPENTEN-l-ONE, 3-METHYL-2-PENTYL-, 65, 26 Cyclopropane, l-trimethy1s1lyloxy-1-ethoxy-, 56, 44 Cyclopropanecarboxylic acid chloride, 66, 176... 

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