Dihalides, organic

Poly sulfide Polymers. These polymers are made up of aliphatic hydrocarbon units connected by di-, tri- or tetrasulfide links. The synthetic rubber found useful in ordn has hydrocarbon units linked by either O or formal segments. The polymers are usually prepd by the condensation of a suitable organic dihalide, usually the chloride, with aq Na polysulfide. According to Ref 8, the most practical organic dichloride is dichlorodiethylformal viz, Bis[ 2[Pg.827]

Preparative Applications of Anionic Silyl Complexes 3.1 Reactions with Organic Dihalides... 

Low intensity ultrasound has also been applied to the Simmons-Smith cyclopropanation of olefins with zinc-diiodomethane (237). This reaction normally will not occur without activation of mossy Zn with I2 or Li, and was difficult to scale-up due to delayed initiation. Yields upon sonication are nearly quantitative, activation of the Zn is unnecessary, and no delayed exotherms are observed. In reactions with another class of organic dihalides, ultrasonic irradiation of Zn with a,a -dibromo-o-xylene has proved a facile way to generate an o-xylylene-like species [Eq. (49)],... 

In the gas phase, the dihalides have an angular structure, but in the solid state, most have complex structures held together by bridging halogen atoms. The gaseous EX4 molecules are tetrahedral, nonpolar, and more soluble in organic solvents than the EX2 compounds. 

A varied and productive chemistry is now established for most of the Group IV dihalides. By combining high temperature and low temperature techniques, one may isolate AX2 species and observe molecular parameters as well as physical and chemical properties. The CX2 (carbenes) and SiX2 (silylenes) molecules have a rich chemistry and provide new and unique opportunities for organic and organo-metallic syntheses. 

HALOGENATION OF ORGANIC SUBSTRATES WITH CHALCOGEN(IV) DIHALIDES... 

The electroreductive coupling of organic dihalides is an interesting approach to synthesize polymers. 

Organic Electroreductive Coupling Reactions using Transition Metal Complexes as Catalysts Table 2. Reductive electropolymerisation of aryl dihalides using nickel catalysts... 

Direct treatment of organic geminal dihalides or trihalides with strongly nucleophilic transition metal complexes can also lead to the formation of carbene complexes, presumably via intermediate a-haloalkyl complexes [484-489]. Examples of such reactions are sketched in Figure 3.17. 

When the alkylating agent is insoluble in liquid ammonia, as in the case of long-chain compounds, an organic solvent is added to the sodium telluride residue after evaporation of the ammonia. Some cyclic and steroidal tellurides have been prepared from sodium telluride in ethanol and the appropriate dihalides. ... 

Diorganyltellurium dihalides are often the primary products in the synthesis of organic derivatives of tellnrinm and are therefore immediate precnrsors of the corresponding tellnrides. 

NaOH solution of the diol and an organic solution of the dihalide in the presence of a phase-transfer catalyst (31). The best results were obtained with dichloro-p-xylene as comonomer and gave polymers with the furanic-aromatic structure 26 ... 

The reducing properties of organic compounds of sulfur, such as methyl mercaptan, show up in partial reduction of trigeminal to geminal dihalides [243]. Dimethyl sulfide reduces hydroperoxides to alcohols and ozonides to aldehydes while being converted to dimethyl sulfoxide [244]. 

Ethylene is also employed as an olefmic component of the Mizoroki-Heck polymerization. Organic dihalides thus couple with ethylene in the presence of a palladium catalyst to afford PAV-type polymers 161 and 162, as shown in Equations (77) and (78). ... 

The direct electrochemical synthesis (Scheme 2) of the addncts of organomagnesinm halides with 2,2 -bipyridine (6) and salts of organodihalogenomagnesinm(II) anions (7) was reported by Hayes and coworkers . Adducts of different stoichiometry and 7 were obtained in the electrochemical oxidation of magnesium in ACN solutions containing organic halides RX (8), a.ro-dihalides XR X (9) and 8 with ammonium salts R NX, respectively. All new products showed none of the typical reactions of Grignard reagents. 

Various organic dihalides are employed in a reaction with sodium polysulfide to produce organic polysulfides (Thiokols). Ethylene dichloride, from the direct chlorination of ethylene, dichloroethyl formal, and /3,0 -dichlorodiethyl ether are the principal dihalides that have been employed in the process (44). These elastomeric polymers have been commercially available for a number of years, and many applications have been developed for them. They have excellent oil resistance and one of their principal uses has been in hose and tank linings in which that property is required. 

The reaction of the dihalides with alcohols is paralleled by their reactions with other organic species containing acid hydrogens, such as phenols, amines and thiols. The resulting compounds are all detailed in Table 7. Representative structures include... 

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