Alcohols metal halide reaction with

Etherification. The reaction of alkyl halides with sugar polyols in the presence of aqueous alkaline reagents generally results in partial etherification. Thus, a tetraallyl ether is formed on reaction of D-mannitol with allyl bromide in the presence of 20% sodium hydroxide at 75°C (124). Treatment of this partial ether with metallic sodium to form an alcoholate, followed by reaction with additional allyl bromide, leads to hexaallyl D-mannitol (125). Complete methylation of D-mannitol occurs, however, by the action of dimethyl sulfate and sodium hydroxide (126). A mixture of tetra- and pentabutyloxymethyl ethers of D-mannitol results from the action of butyl chloromethyl ether (127). Completely substituted trimethylsilyl derivatives of polyols, distillable in vacuo, are prepared by interaction with trimethylchlorosilane in the presence of pyridine (128). Hexavinylmannitol is obtained from D-mannitol and acetylene at 25.31 MPa (250 atm) and 160°C (129). 

Silver(I) compounds are often used to generate cationic metal complexes from the corresponding metal halides. Suzuki and coworkers found that -hexylzirconocene chloride (61), derived from 1-hexene and Schwartz reagent 60, can react with aldehydes in the presence of a catalytic amount of AgAsFs to give secondary alcohols [27]. The reaction with hydrocinnamaldehyde, for example, provides the alcohol 62 in 95 % yield (Sch. 14). Allylic alcohols are also obtainable by a similar procedure using 1-hexyne as a starting material. 

The reactivities of alkyl halides are in the sequence RI > RBr > RCl and MeX > EtX > PrX. Benzyl halide reactions with tin do not require catalysts (equation 2). For less reactive halides, the catalysts and promoters employed include metals (sodium, magnesium, zinc, or copper), Lewis bases (amines, triorganophosphines and -stibines, alcohols, or ethers), iodides, and onium salts (R4MX). The use of tin-sodium alloys can result in tri- or tetraorganotin products. Electrochemical synthesis has also been reported, e.g. the formation of R2SnX2 from the oxidation of anodic tin by RX in benzene solution and the formation of R4Sn from RI (R = Me or NCCH2CH2) and cathodic tin. 

Sulfenamides can be synthesized by a metal-assisted reaction with disulfides and amines (eq 13). Conjugated dienols can be synthesized in a highly chemo-, regio-, and stereoselective manner from vinylic halides and allylic alcohols (eq 14). Silver acetate (or silver carbonate) and a catalytic amount of palladium(II) acetate in DMF are the preferred conditions. The reaction is very attractive because it requires only one functionalized alkene reactant and the addition of the vinylic group only occurs at the terminal carbon of the aUyUc alcohol. 4... 

In the reaction with hydrogen halides, the C—O bond in the alcohol breaks. However, in some other reactions the O—H bond in the alcohol breaks. The reaction with sodium metal is an example ... 

Both reactants m the Williamson ether synthesis usually originate m alcohol pre cursors Sodium and potassium alkoxides are prepared by reaction of an alcohol with the appropriate metal and alkyl halides are most commonly made from alcohols by reaction with a hydrogen halide (Section 4 7) thionyl chloride (Section 4 13) or phosphorus tri bromide (Section 4 13) Alternatively alkyl p toluenesulfonates may be used m place of alkyl halides alkyl p toluenesulfonates are also prepared from alcohols as their imme diate precursors (Section 8 14)... 

From Metal Halides. The reaction of metal chlorides with alcohols can give metal chloride alkoxides (67—69), eg... 

Alcohols undergo many reactions and can be converted into many other functional groups. They can be dehydrated to give alkenes by treatment with POCI3 and can be transformed into alkyl halides by treatment with PBr3 or SOCU- Furthermore, alcohols are weakly acidic (p/C, — 16-18) and react with strong bases and with alkali metals to form alkoxide anions, which are used frequently in organic synthesis. 

The ionic P-P bond polarization renders P-phosphino-NHPs highly active reactants for various metathesis and addition reactions at exceedingly mild conditions. Metathesis is observed in reactions with alcohols, chloroalkanes, and complex transition metal halides (Schemes 11 and 12) [39, 73], Of particular interest are the reactions with chlorotrimethylstannane which yield equilibria that are driven by a subtle balance of P-X bond strengths to yield either diphosphines or P-chloro-NHPs as preferred product (Scheme 11). Chlorotrimethylsilane does not react with... 

In the present paper we are concerned principally with the initiation step. The new observations and suggestions regarding this step put forward by Polanyi and his collaborators [17-21] marked the first real practical and theoretical advance since the work of Whitmore. They found that in the polymerization of isobutene by TiCl4 or BF3, both at room temperature and at very low temperatures, the metal halide alone was inactive, and that a third component, the co-catalyst, was required to initiate the polymerization. The word co-catalyst was chosen for the substances concerned, by analogy with co-enzyme . It is to be preferred to the term promoter , often used by American workers, as this indicates a substance which speeds up a reaction which would also take place in its absence, and since the characteristic of co-catalysts is that they are essential to the reaction. The first co-catalyst to be discovered was water, but shortly afterwards certain alcohols and acids were found to act in a similar manner. 

Solid-state metathesis reactions. For a number of compounds, solid-state metathesis (exchange) reactions have the advantages of a rapid high-yield method that starts from room-temperature solids and needs little equipment. The principle behind these reactions is to use the exothermicity of formation of a salt to rapidly produce a compound. We may say that for instance a metal halide is combined with an alkali (or alkaline earth) compound of a /7-block element to produce the wanted product together with a salt which is then washed away with water or alcohol. Metathesis reactions have been used successfully in the preparation of several crystalline refractory materials such as borides, chalcogenides, nitrides. 

Another general method for converting alcohols to halides involves reactions with halides of certain non-metallic elements. Thionyl chloride, phosphorus trichloride, and phosphorus tribromide are the most common examples of this group of reagents. These reagents are suitable for alcohols that are neither acid-sensitive nor prone to structural rearrangements. The reaction of alcohols with thionyl chloride initially results in the formation of a chlorosulfite ester. There are two mechanisms by which the chlorosulfite... 

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