Vinylidene reactions

The mechanism for the ethylene to methylcarbene reaction has been calculated at the DFT (B3PW91) level with the model system RuHCl(PH3)2 [8, 21]. As in the case of the acetylene to vinylidene reaction, the starting complex was assumed to be the 14-electron complex RuHCl(PH3)2 generated in situ. The reaction path is very similar to that obtained with C2H2. They differ mainly in the overall direction of the energy pattern downhill for acetylene and uphill for ethylene. 

Af-vinyl carbazole, reaction type 212 vinyl chloride, reaction type 212 vinyl ester, reaction type 212 vinyl ether, reaction type 212 vinyl fluoride, reaction type 212 vinylidene, reaction type 212 chloride At-vinylpyrrolidone, reaction type 212 virus, tobacco necrosis, crystal structure 166... 

In addition to alcohols, some other nucleophiles such as amines and carbon nucleophiles can be used to trap the acylpalladium intermediates. The o-viny-lidene-/j-lactam 30 is prepared by the carbonylation of the 4-benzylamino-2-alkynyl methyl carbonate derivative 29[16]. The reaction proceeds using TMPP, a cyclic phosphite, as a ligand. When the amino group is protected as the p-toluenesulfonamide, the reaction proceeds in the presence of potassium carbonate, and the f>-alkynyl-/J-lactam 31 is obtained by the isomerization of the allenyl (vinylidene) group to the less strained alkyne. 

Poly(vinylidene Chloride). Poly(vinylidene chloride) is prepared according to the following reaction ... 

Polypropylene polymerized with triethyl aluminum and titanium trichloride has been found to contain various kinds of chain ends. Both terminal vinylidene unsaturation and aluminum-bound chain ends have been identified. Propose two termination reactions which can account for these observations. Do the termination reactions allow any discrimination between the monometallic and bimetallic propagation mechanisms ... 

Addition of anhydrous hydrogen chloride to vinylidene fluoride is reported to be accompanied by a hazardous (explosive) side reaction [53]. 

Sodium 2 methoxy ethoxide, reaction with vinylidene chloride to yield ketcne di(2 methoxyetbyl) acetal, 47, 78... 

Other types of side reactions take place with the thioamidation of copolymers from AN and vinylidene chloride or vinyl chloride60. ... 

These copolymers undergo side reactions which are mainly reducible to reactions in which chloride atoms take part. When copolymers of AN and vinylidene chloride are treated with aqueous solutions of ammonium sulfide at 90 °C, nitrile groups have been shown to be almost fully converted into thioamide groups, and practically no hydrolysis of the formed thioamide groups is taking place in this case. At the same time, it was found that in the course of this treatment dehydrochlorination is taking place almost quantitatively ... 

In the reactions of the fluoro-olefins, steric factors are of lesser importance because of the relatively small size of the fluoro-substitucnt.3 Fluorine and hydrogen are of similar bulk. In these circumstances, it should be expected that polar factors could play a role in determining regiospecificity. Application of the usual rules to vinylidene fluoride leads to a prediction that, for nucleophilic... 

Propagation reactions involving the fluoro-olefins, vinyl fluoride (VF)6Q 7 vinylidene fluoride (VF2)69 7""74 and trifluoroethylene (VF3),75 show relatively poor rcgiospccificity. This poor specificity is also seen in additions of small... 

The synthesis of 2-chloro-2,3,3-trifluorocyclobutyl acetate illustrates a general method of preparing cyclobutanes by heating chlorotrifluoroethylene, tetrafluoroethylene, and other highly fluorinated ethylenes with alkenes. The reaction has recently been reviewed.11 Chlorotrifluoroethylene has been shown to form cyclobutanes in this way with acrylonitrile,6 vinylidene chloride,3 phenylacetylene,7 and methyl propiolate.3 A far greater number of cyclobutanes have been prepared from tetrafluoroethylene and alkenes 4,11 when tetrafluoroethylene is used, care must be exercised because of the danger of explosion. The fluorinated cyclobutanes can be converted to a variety of cyclobutanes, cyclobutenes, and butadienes. 

Foremost among the classes of the nonaromatic unsaturated systems is that of compounds in which the substituent is bonded to a carbon-carbon double bond. It is convenient to divide the data sets for carbon-carbon double bonds into five categories vinyl, vinylidene, frans-vinylene, cis-vinylene, and reactions of carbon-carbon double-bond sets. 

The vinylidene group, the rro s-CPh=C- group, and the methylene group, all of which have one atom intervening between the substituent and the reaction site, all show Ji values of about 4. The cyclopropylidene group is an exception to this observation, with Ji of 6.38. As there were only four points in the set from which a was obtained, this deviation may not be real. The C—CPh=C group has a somewhat low value for 7j of 3.39. 

Polymerizations conducted in nonaqueous media in which the polymer is insoluble also display the characteristics of emulsion polymerization. When either vinyl acetate or methyl methacrylate is polymerized in a poor solvent for the polymer, for example, the rate accelerates as the polymerization progresses. This acceleration, which has been called the gel effect,probably is associated with the precipitation of minute droplets of polymer highly swollen with monomer. These droplets may provide polymerization loci in which a single chain radical may be isolated from all others. A similar heterophase polymerization is observed even in the polymerization of the pure monomer in those cases in which the polymer is insoluble in its own monomer. Vinyl chloride, vinylidene chloride, acrylonitrile, and methacryloni-trile polymerize with precipitation of the polymer in a finely divided dispersion as rapidly as it is formed. The reaction rate increases as these polymer particles are generated. In the case of vinyl chloride ... 

In 1998, Wakatsuki et al. reported the first anti-Markonikov hydration of 1-alkynes to aldehydes by an Ru(II)/phosphine catalyst. Heating 1-alkynes in the presence of a catalytic amount of [RuCljlCgHs) (phosphine)] phosphine = PPh2(QF5) or P(3-C6H4S03Na)3 in 2-propanol at 60-100°C leads to predominantly anti-Markovnikov addition of water and yields aldehydes with only a small amount of methyl ketones (Eq. 6.47) [95]. They proposed the attack of water on an intermediate ruthenium vinylidene complex. The C-C bond cleavage or decarbonylation is expected to occur as a side reaction together with the main reaction leading to aldehyde formation. Indeed, olefins with one carbon atom less were always detected in the reaction mixtures (Scheme 6-21). 

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