Organometallic compounds vinyl

In more recent years two new types of antifouling composition have been developed, using organometallic compounds as poisons. In one type, based chiefly on vinyl resin and organotin compounds (e.g. tributyltin fluoride), the poison and resin form a solid solution. As the poison dissolves from the surface of the film, more poison diffuses from deeper in the film to... 

Addition of vinylic organometallic compounds to unsaturated carbonyl compounds addition of organometallic compounds to acetylenic carbonyl compounds... 

Cyanation of vinylic organometallic compounds Addition to activated alkynes (Michael)... 

Seifert, D. Organometallic Compounds with a Vinyl Group, Moscow, Mir Publishers 1964, (Russ. Transl.)... 

In this study the relationship between the structure of organometallic compounds and their ability to polymerize vinyl monomers and olefins will be examined. The objective is to identify methods of synthesis for polymerization catalysts that are more selective and more active than the systems currently available. 

Alkenes frequently have two kinds of C—H bonds, vinyl and allyl, that are generally more acidic than the C—H bonds of saturated alkanes. Quantitative measures of acidity are related to the chemistry of the corresponding carbanions and carbanion salts or organometallic compounds. Several methods have been used for the study of anions in the gas phase1. For many acids it is possible to measure equilibrium constants for equilibria of the type in equation 1. From such equilibrium constants with compounds RH of independently known gas-phase acidity, it has been possible to determine the acidities of a wide range of compounds2. 

Ziegler-Natta catalyst. Organometallic compounds used in vinyl polymerization to control tacticity. 

Isomerization of a-hydroxy alkynes and alkynones 2-15 Acylation of olefins 2-27 From lithium acetylides 2-32 From vinylic organometallic compounds... 

Unsaturated Nitriles, Nitro Compounds, and Sulfonic Acids and Esters 2-33 Cyanation of vinylic organometallic compounds... 

Heat stabilizers protect polymers from the chemical degrading effects of heat or uv irradiation. These additives include a wide variety of chemical substances, ranging from purely organic chemicals to metallic soaps to complex organometallic compounds. By far the most common polymer requiring the use of heat stabilizers is poly(vinyl chloride) (PVC). However, copolymers of PVC, chlorinated poly(vinyl chloride) (CPVC), poly(vinylidene chloride) (PVDC), and chlorinated polyethylene (CPE), also benefit from this technology. Without the use of heat stabilizers, PVC could not be the widely used polymer that it is, with worldwide production of nearly 16 million metric tons in 1991 alone (see VlNYL polymers). 

Ketones can be a-brominated on solid phase by treatment with synthetic equivalents of bromine, such as pyridinium tribromide (Entry 2, Table 6.1) or phenyltri-methylammonium tribromide (DCM, 20 °C, 3 h [10]). Resin-bound organometallic compounds, such as vinylstannanes [11] or organozinc derivatives [12], react cleanly with iodine to yield the corresponding vinyl or alkyl iodides (see also Section 3.13). Additions of halogens or their synthetic equivalents to C=C double bonds on cross-... 

More reactive carbon nucleophiles than enolates can also be prepared on insoluble supports (see Chapter 4) and are used to convert aldehydes or ketones into alcohols. Organolithium compounds have been generated on cross-linked polystyrene by deprotonation of formamidines and by metallation of aryl iodides (Table 7.5). Similarly, support-bound organomagnesium compounds can be prepared by metallation of aryl and vinyl iodides with Grignard reagents. The resulting organometallic compounds react with aldehydes or ketones to yield the expected alcohols (Table 7.5). 

A thermographic material with only one heat-sensitive component is prepared by reaction of an organometallic compound such as phenylmercury(II) nitrate with a thiourea derivative.230 The product is ball milled and coated in a binder such as poly(vinyl acetate). Other organometallic compounds disclosed are those of bismuth, tin, gallium and germanium combined with a variety of sulfur-containing compounds such as thioamides and xanthates. 

One requirement is diat the pKa of die new organometallic compound is lower than die pKa of die starting organometallic. This in essence means that the equilibrium is driven to products by die formation of a more stable anion. This metiiod is commonly used to make vinyl lithiums from vinyl halides and alkyl lithiums and aryl lithiums from aryl halides and alkyl litiiiums because the electron pair in an sp2 orbital of a vinyl or aryl litiiium compound is more stable than the electron pah in an sp3 orbital of an alkyl lithium. 

Transition metal-catalyzed cross-coupling reactions between vinyl organometallic compounds and unactivated alkyl halides that can be usually performed with palladium, nickel and cobalt are of particular synthetic interest [37-39]. Recently, the groups of Cahiez [48] and Cossy [49] concurrently reported the first iron-catalyzed reaction of alkenyl Grignard compounds with primary and secondary alkyl halides (X=Br, I) (Scheme 5.15). The two protocols basically differ in the iron source... 

---