Vinyl preparation

Using ethene in ethanoic acid at 70-80 C it is possible to prepare vinyl acetate (ethenyl ethanoate) in good yields. 

The reaction of aldehydes with carbon tetrachloride in the presence of excess tris(dimethylamino)phosphine has been used to prepare vinyl dihalides in yields of 50—70%. It is suggested that the reaction takes place via an intermediate salt (77), although the formation of this salt seems more likely to be analogous to the Perkow reaction than to involve attack on oxygen. 

The monomer from which the vinyl plastic polyvinyl chloride (PVC) is prepared. Vinyl chloride was originally made by passing acetylene and hydrogen chloride over a mercury chloride catalyst at a temperature of about 180 °C. Now made from ethylene chloride which is converted to vinyl chloride by contact with a catalyst at about 500 °C (900 °F) or by reaction with dilute caustic alkali at about 150 °C (300 °F). 

From the same zirconocene intermediates, Huang and co-workers have prepared vinyl sulfides [24,35] and sulfones [26] through use of the appropriate quenching agents (Scheme 4.6). Treatment of vinyl zirconocenes with an equivalent of a disulfide in THF at 60 °C affords, after work-up and purification, (E)-vinyl sulfides in good isolated yields. Vinyl sulfones, which as a class are generally useful as Michael acceptors and Diels—Alder dienophiles, are obtained in about two hours upon treatment of (fc)-vinyl zirconocenes with various sulfonyl chlorides in THF at 40°C. 

Scheme 8 summarizes some of the reactions that have been observed for H2Os3(CO)10 (135,136, 165). A wide range of products may be obtained, but some of the reactions are complicated by hydrogenation of the products, a situation that does not occur in the displacement reactions considered above. This reagent was the first used to prepare vinyl adducts from alkenes and alkynes. 

Examples of the use of this procedure to prepare vinyl triflates from ketones are provided in Table II. Often mixtures of cis and trans isomers as well as the various double bond isomers of vinyl triflates are obtained by this procedure, and the amounts of these isomers produced may vary with the base and solvent used. Also, small amounts of unchanged ketone may contaminate the initial crude product. Consequently, separation procedures such as preparative gas chromatography or efficient fractional distillation may be required to obtain a single vinyl triflate isomer. 

Although vinyl fluoride was prepared around 1900, it was believed to be resistant to typical vinyl polymerization. German scientists prepared vinyl fluoride through reaction of acetylene with hydrogen fluoride in the presence of catalysts in 1933. 

A convenient method for preparing vinylated or arylated pyridines on insoluble supports is palladium-mediated cross-coupling. The Heck, Suzuki, and Stille reactions have been successfully used for this purpose (Table 15.22). The conditions are essentially the same as those used for the related coupling of arenes (see Section 5.4). 

There are several methods to prepare vinyl fluoride (VF) monomer. One of the methods described in patent literature is a two-step method.60 The first step is the reaction of hydrogen fluoride with acetylene in the presence of a suitable catalyst to yield ethylidene fluoride, which is subsequently pyrolyzed ... 

Perhaps the most important development in the area of addition polymerization was the discovery of a method for preparing vinyl polymers using metal catalysts. This breakthrough earned Karl Ziegler and Giulio Natta the 1963 Nobel Prize in chemistry... 

One straightforward route to the aziridine ring system is available through the ring closure of vicinal amino alcohols, an approach which has been used to prepare vinyl N-H aziridines. Thus, 4-amino-l-phenylhex-5-en-3-ol (111) was treated with sulfuryl chloride to provide the sulfamidate 112, which underwent clean thermolysis at 70 °C to form the vinyl aziridine 113 in 97% overall yield <02T5979>. 

If unusual vinylic tellurides or vinylic tellurides of defined stereochemistry are required, other vinyl organo-metallics are employed. In recent years, a number of methods of preparing vinylic derivatives of tellurium using organotellurium halides have been developed. 

Diorganoditellurides are used as the tellurating agent in a catalytic process involving vinylic boranes 114 to prepare vinylic tellurides 115 (Scheme 68).184... 

Table I. Ingredients Used in Preparing Vinyl Acetate—VV911 Latexes...

In view of the fact that benzylic cations are responsible for the initiation, graft copolymerization is feasible when the polymer supported pyridinium salts are employed. Endo and co-workers [41] prepared vinyl monomers having pyridinium salt structure. In this case, p-chloromethyl styrene was used as the benzyl halide and the general synthetic strategy was followed. The polymerizable salt was then homo and copolymerized with styrene (Scheme 7). 

This coupling is equally applicable to alkyl-, aryl-, and vinyllithium reagents. The products are obtained in generally good yield and in 98-100% isomeric purity. The reaction can also be used to prepare vinyl sulfides from vinyl halides and a lithium thiolate (equation II). 

The methoxymethyl cation can be obtained as a stable sohd, MeOCHj SbF, Carbocations containing either a, p, or y silicon atom are also stabilized, relative to similar ions without the silicon atom. In super acid solution, ions such as CX (X = Cl, Br, I) have been prepared. Vinyl-stabilized halonium ions are also known. ... 

A useful, although somewhat limited, method of preparing vinyl azides involves the addition of azide ion to vinyl halides with subsequent elimination of halide ion. This reaction is only possible when the halogen is located to a group which can effectively stabilize the intermediate carbanion. A number of alkyl and aryl substituted )3-chlorovinyl ketones (23) have been found to react in this way ". In many cases, however, the resulting /3-azidovinyl ketones (26) cannot... 

Wakatsuki and co-workers 287) have prepared vinyl ether complexes of Pd(II) and Pt(II) of composition [CI2ML] (M = Pd or Pt L = vinyl ethers, propenyl ethers, 1,2-dimethoxyethylene) by displacement of PhCN from Pd(PhCN)2Cl2- They are fairly stable at 25°C. Since these ethers would be good a donors but poor tt acceptors, the stability of these complexes suggest that a donation is most important with tt complexes of Pd(II) and Pt(II). This conclusion is in agreement with earlier IR studies, as well as a recent NMR study of Pt olefin and acetylene complexes 35). Furthermore, a study of complex formation... 

If hydration of acetylene followed the same pattern as hydration of alkenes, we would expect addition of H— and —OH to the triple bond to yield the structure that we would call vinyl alcohol. But all attempts to prepare vinyl alcohol result— like hydration of acetylene—in the formation of acetaldehyde. 

Eighteen years ago, in the course of unsuccessful attempts to prepare vinyl chloroformate by phosgenation of aldehydes in presence of tertiary amines, especially pyridine, we discovered a new route to a-chloroalkyl chloroformate (Ref. 58) as presented in scheme 58 ... 

In spite of numerous failures to prepare vinyl chlorofor-mate and Isopropenyl chloroformate by direct phosgenatlon of either acetaldehyde or acetone, we accepted the challenge to find economical routes to vinylic chloroformates and their derivatives, vinylic carbonates and carbamates. 

There are a few efficient methods for the stereoselective synthesis of vinyl halides, and this transformation remains a synthetic challenge. Research by S. Roy showed that the Hunsdiecker reaction can be made metal free and catalytic catalytic Hunsdiecker reaction) and can be used to prepare ( )-vinyl halides from aromatic a,p-unsaturated carboxylic acids. The unsaturated aromatic acids were mixed with catalytic amounts of TBATFA and the A/-halo-succinimide was added in portions over time at ambient temperature. The yields are good to excellent even for activated aromatic rings which do not undergo the classical Hunsdiecker reaction. The fastest halodecarboxylation occurs with NBS, but NCS and NIS are considerably slower. The nature of the applied solvents is absolutely critical, and DCE proved to be the best. This strategy was extended and applied in the form of a one-pot tandem Hunsdiecker reaction-Heck coupling to prepare aryl substituted (2 ,4 )-dienoic acids, esters, and amides. 

Polymerization, Copolymerization, and Grafting. In this work we have prepared vinyl and isopropenyl derivatives of 2(2-hydroxyphenyl)2H-benzotriazoles 2H5V, 2H5P, and 2(2-hydroxy-5-methylphenyl)2H-4 — vinyl-benzotriazole 2H5V and 2(2-hydroxy-5-methylphenyl)2H-4-vinyl-benzotriazole were hcanopolymerized and copolymerized with styrene,... 

The selenium group can be removed under very mild oxidative conditions (Scheme 44). Treatment of the anion of (65) with TMS-Cl gives another reagent that can be deprotonated and used with various electrophiles to prepare vinyl silyl ketones (Scheme 45). Therefore, (65) can be used as synthons of (6) and (66), like the 1,3-di(methylthio)allyl anions. ... 

Poly( vinyl alcohol) is a versatile polymer with many industrial applications, and it may be the only polymer with an all carbon-carbon bond backbone that is truly biodegradable. The monomer is vinyl acetate, which is readily polymerized with free radical initiators to form poly(vinyl acetate), and the latter can be hydrolyzed either partially to prepare vinyl alcohol-vinyl acetate copolymers, or fully to prepare poly(vinyl alcohol). At high vinyl alcohol contents, the copolymers, and the vinyl alcohol homopolymer, are water soluble, and the aqueous solutions of these polymers find many applications for example, as adhesives or for coatings. The homopolymer and the very high vinyl alcohol copolymers are crystalline with melt transitions between 180 and 230 °C and glass transitions between 58 and 85 °C, depending on the vinyl alcohol content. The polymers can be melt processed to form molded plastics, fibers and films [36]. 

N3, carbanions, and others, it is possible to prepare vinyl compounds by substitution on vinyl carbons. In some cases, a nucleophilic addition which leads to bifunctional products is possible (nucleophilic addition). There are numerous examples which can be explained by this mechanism. 

An entirely different approach to sugar-based polymers involves the use of selective enzymatic catalysts to prepare vinyl sugar monomers that are subsequently polymerized via chemical catalysts. Tokiwa and Kitagawa (25) published extensively on this subject, and their contribution within this book describes a wide range of sugar monomer structures. 

An alternative method for preparing vinyl bromides can be incorporated into a synthesis of alkynes when combined with an E2 reaction. In Jacobi s synthesis of (-)-stemoamide,l aldehyde 196 was treated with... 

Qin and coworkers were next able to prepare vinyl iodide 118 in five steps from the Nl-methylindole congener of tetracycle 117, but were unable to complete the total synthesis of vincorine (18) from this intermediate (Scheme 6). 

Uses The isopropanolamine soaps may be emplayed in oil uses now found far the ethanolamine soaps. Their excellent hydrocarban solubility and color stability make them af special interest in soluble ails, dry cleaning soaps, cosmetics, and pharmaceutical preparations. Vinyl acetate resin emulsions of the ail in-water type far coating fabrics and leather have excellent stability when prepared by stirring 80 parts by weight of Vinylite" resin AYAF (30% solution in toluene) and 1 part oleic acid, into 20 parts of water containirsg 0.6 to 0.8 parts af mixed isopropanolamine. 

The vinyl ether 219 was synthesized as shown in Scheme 49. Noyori asymmetric hydrogenation of a j6-keto ester derived from 224 generated the stereo-genic center in 225 with > 95% ee. According to Bunnelle s method [99], 225 was converted into allylsilane 226. Rychnovsky developed a new method for preparing vinyl ether, because of its sensitivity chloroacetylation and... 

Amongst the alternatives to phosphorus-based olefination procedures, the use of sulphones remains popular. Thus, fluoromethyl phenyl sulphone has been used to prepare vinyl fluorides via ot-... 

This reaction is often used to prepare vinyl- and aryl-lithium compounds 8 from the reaction of halo-benzene 6 and alkyl-lithium 7 species (Leroux and Schlosser 2002) (Scheme 7.3). 

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