Metalation of Acidic Hydrocarbons

Numerous polylithiated aliphatic hydrocarbons have been prepared by polymetalation of the corresponding hydrocarbons and only a few characteristic examples can be given. 

Propyne interestingly can be perlithiated with n-butyllithium in hexane to yield the lithiocarbon CjLi 26 as a deep red-brown solution After evaporation of the 

The isomeric allene, on the other hand, using n-butyllithium in hexane/THF (1 1) at —50 °C is metalated only to the dianion 24 

Controlled dilithiation of propyne can be achieved by using two equivalents of n-butyllithium in hexane/ether in the presence of one equivalent of TMEDA 

Upon boiling 1-butyne with excess n-butyllithium in hexane a rapid dimetalation takes place without the intermediate acetylide 153 being precipitated The same dilithiobutyne 154 was obtained starting with 1,2-butadiene. 

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The metallation of acidic hydrocarbons (pK 15-30), such as ketones and esters, and their nitrogen-containing analogues are complicated because the substrates contain a reactive electrophilic center. Sterically hindered RjNM, (CgH5)3CM or nonnucleophilic... 

Lithium metal may react with acidic hydrocarbons to give organolithiums. This reaction also occurs with other alkali metals, more commonly with the heavier group-IA metals potassium and Cs (see 5.5.3.2.4). Usually, deprotonation of acidic hydrocarbons ( 5.5.2.3.2) is the method of choice for organolithiums from acidic hydrocarbons, but in special cases where contaminants must be avoided, the direct reaction with Li metal can be useful. 

Other typical reactions of acidic hydrocarbons with alkali metals are given in Table 1. Example 4 (Table 1) shows that, in addition to hydrogenation of multiple bonds, reductive cleavage may be a complicating side reaction. In the reaction of triphenylmeth-ane this side reaction may be eliminated by addition of butadiene which, as its radical anion, acts as proton acceptor. 

The principal methods for forming the carbon-tin bond involve the reaction of organo-metallic reagents with tin compounds (equation 4-1), the reaction of stannylmetallic compounds with organic halides (equation 4-2), the reaction of tin or tin(II) compounds with alkyl halides (equation 4-3), the hydrostannation of alkenes or alkynes (equation 4-4), the reaction of acidic hydrocarbons with Sn-0 and Sn-N bonded compounds (equation 4-5), and carbonyl-forming eliminations (equation 4-6) the symbol sn represents 4Sn. 

The carbon—M bonds also form by cocondensation of acidic hydrocarbons with alkaline-earth metal vapor. In this way the cyclopentadienides and indenyl compounds of Ca, Sr and Ba that are difficult to obtain by other methods for Sr and not at all for Ba can be prepared nearly quantitatively. Because of the required vacuum techniques, this method is suitable for the preparation of small amounts only. 

Allenyl-lithium reagents, generated by metallation of allenic hydrocarbons or from haloallenes by halogen-metal exchange, react with various electrophiles with retention of the allenic structure to give functionalized allenes. High yields of allenylsilanes and sulphides, allenic acids and dialkylamides, and fi-allenic alcohols are available by this method. However, additions to ketones are less satisfactory since propargylic alcohols are formed in some cases. 

Metallation of weak hydrocarbon acids by potassium hydride-18-crown-6 poly ether in tetrahydrofuran and the relative acidity of molecular hydrogen. E. Buncel and B. Menon, J. C. S. Chem. Commun., 648 (1976)... 

Butane-Naphtha Catalytic Liquid-Phase Oxidation. Direct Hquid-phase oxidation ofbutane and/or naphtha [8030-30-6] was once the most favored worldwide route to acetic acid because of the low cost of these hydrocarbons. Butane [106-97-8] in the presence of metallic ions, eg, cobalt, chromium, or manganese, undergoes simple air oxidation in acetic acid solvent (48). The peroxidic intermediates are decomposed by high temperature, by mechanical agitation, and by action of the metallic catalysts, to form acetic acid and a comparatively small suite of other compounds (49). Ethyl acetate and butanone are produced, and the process can be altered to provide larger quantities of these valuable materials. Ethanol is thought to be an important intermediate (50) acetone forms through a minor pathway from isobutane present in the hydrocarbon feed. Formic acid, propionic acid, and minor quantities of butyric acid are also formed. 

In general, the reactions of the perfluoro acids are similar to those of the hydrocarbon acids. Salts are formed with the ease expected of strong acids. The metal salts are all water soluble and much more soluble in organic solvents than the salts of the corresponding hydrocarbon acids. Esterification takes place readily with primary and secondary alcohols. Acid anhydrides can be prepared by distillation of the acids from phosphoms pentoxide. The amides are readily prepared by the ammonolysis of the acid haUdes, anhydrides, or esters and can be dehydrated to the corresponding nitriles (31). 

Pyrolyses of formates, oxalates and mellitates yield CO and C02 (H2, H20 etc.) as the predominant volatile products and metal or oxide as residue. It is sometimes possible to predict the initial compositions from thermodynamic considerations [94], though secondary reactions, perhaps catalyzed by the solids present, may result in a final product mixture that is very different. The complex mixtures of products (hydrocarbons, aldehydes, ketones, acids and acid anhydrides) given [1109] by reactants containing larger organic groupings makes the collection of meaningful kinetic data more difficult, and this is one reason why there are relatively few rate studies available for the decompositions of these substances. 

To optimize the alkylation conditions, ferrocene was reacted with allyldimethyl-chlorosilane (2) in the presence of various Lewis acids such as aluminum halides and Group lO metal chlorides. Saturated hydrocarbons and polychloromethanes such as hexane and methylene chloride or chloroform were used as solvents because of the stability of the compounds in the Lewis acid catalyzed Friedel-Crafts reactions. The results obtained from various reaction conditions are summarized in Table IV. 

In 1970, Monroe and Rooker(28) claimed the use of aluminum salts of acid orthophosphate esters as viscosity builders for use in fracturing fluids. The application of these materials began a new era of hydrocarbon gelling agents. Monroe(29) later claimed the use of Fe30it as a metal activator of phosphate esters and in 1971 described several other metals(30) that could be used with amine neutralization agents. Numerous metallic ionic derivatives can be used as effective "activators" or crosslinkers to prepare a gel. 

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