Potassium reactions with review

Potassium Hydride. Potassium hydride [7693-26-7] KH, made from reaction of molten potassium metal with hydrogen at ca 200°C, is suppHed in an oil dispersion. Pressure Chemical Company (U.S.) is a principal suppHer. KH is much more effective than NaH or LiH for enolization reactions (63,64). Use of KH as a base and nucleophile has been reviewed (65). 

Two complementai y reviews of this subject are by Shah et al. AIChE Journal, 28, 353-379 [1982]) and Deckwer (in de Lasa, ed.. Chemical Reactor Design andTechnology, Martinus Nijhoff, 1985, pp. 411-461). Useful comments are made by Doraiswamy and Sharma (Heterogeneous Reactions, Wiley, 1984). Charpentier (in Gianetto and Silveston, eds.. Multiphase Chemical Reactors, Hemisphere, 1986, pp. 104—151) emphasizes parameters of trickle bed and stirred tank reactors. Recommendations based on the literature are made for several design parameters namely, bubble diameter and velocity of rise, gas holdup, interfacial area, mass-transfer coefficients k a and /cl but not /cg, axial liquid-phase dispersion coefficient, and heat-transfer coefficient to the wall. The effect of vessel diameter on these parameters is insignificant when D > 0.15 m (0.49 ft), except for the dispersion coefficient. Application of these correlations is to (1) chlorination of toluene in the presence of FeCl,3 catalyst, (2) absorption of SO9 in aqueous potassium carbonate with arsenite catalyst, and (3) reaction of butene with sulfuric acid to butanol. 

Alkyl fluorides have been prepared by reaction between elementary fluorine and the paraffins, by the addition of hydrogen fluoride to olefins, by the reaction of alkyl halides with mercurous fluoride, with mercuric fluoride, with silver fluoride, or with potassium fluoride under pressure. The procedure used is based on that of Hoffmann involving interaction at atmospheric pressure of anhydrous potassium fluoride with an alkyl halide in the presence of ethylene glycol as a solvent for the inorganic fluoride a small amount of olefin accompanies the alkyl fluoride produced and is readily removed by treatment with bromine-potassium bromide solution. Methods for the preparation of alkyl monofluorides have been reviewed. ... 

The reaction of alkyl halides with metal nitrites is one of the most important methods for the preparation of nitroalkanes. As a metal nitrite, silver nitrite (Victor-Meyer reaction), potassium nitrite, or sodium nitrite (Kornblum reaction) have been frequently used. The products are usually a mixture of nitroalkanes and alkyl nitrites, which are readily separated by distillation (Eq. 2.47). The synthesis of nitro compounds by this process is well documented in the reviews, and some typical cases are listed in Table 2.3.92a Primary and secondary alkyl iodides and bromides as well as sulfonate esters give the corresponding nitro compounds in 50-70% yields on treatment with NaN02 in DMF or DMSO. Some of them are described precisely in vol 4 of Organic Synthesis. For example, 1,4-dinitrobutane is prepared in 41 -46% yield by the reaction of 1,4-diiodobutane with silver nitrite in diethyl ether.92b 1-Nitrooctane is prepared by the reaction with silver nitrite in 75-80% yield. The reaction of silver nitrite with secondary halides gives yields of nitroalkanes of about 15%, whereas with tertiary halides the yields are 0-5%.92c Ethyl a-nitrobutyrate is prepared by the reaction of ethyl a-bromobutyrate in 68-75% yield with sodium nitrite in DMF.92d Sodium nitrite is considerably more soluble in DMSO than in DMF as a consequence, with DMSO, much more concentrated solutions can be employed and this makes shorter reaction times possible.926... 

In 1972, we reported a general procedure for the preparation of highly reactive metal powders. The basic procedure involved the reduction of a metal salt in a hydrocarbon or ethereal solvent. The reductions are most generally carried out with alkali metals such as potassium, sodium, or lithium. A wide range of methods have been developed to carry out the reductions. The reactivities of these resulting black powders exceed other reports in the literature for metal powders. This high reactivity has resulted in the development of several new synthetic techniques and vast improvements in many older, well established reactions. This review concentrates on the metals Mg, Ni, Zn, Cd, Co, Cu, Fe, and U. 

There have been reviews of nucleophilic substitution103 and of deoxidative nucleophilic substitution 104 in heterocyclic A -oxidcs. Stable carbon-carbon-bonded adducts, such as (22), have been reported from the reactions of 6-phenyl-1,2,4-triazine 4-oxides with phenols oxidation of the adducts may be achieved by reaction with potassium permanganate in acetone.105... 

Borohydride reduction of a diketone followed by dehydrative thermolysis is a good method of producing an isobenzofuran free of the diketone [2391]. Acid-catalysed dehydrative cyclization of the diketone (30.2) is an alternative route [2281] to isobenzofurans (review [3508]. An o-acylbenzaldehyde may be cyclized by reaction with potassium cyanide-acetic acid [2100]. 

Before 1960, only sodamide and potassium amide were used for the a-metallation of nitriles ( CH—C=N) and successful couplings with electrophiles were restricted to alkylations [la]. The extension of the number of base-solvent systems allowed a clean a-metallation of a variety of nitriles and the subsequent successful reaction with other nucleophiles [lb]. The use of a-metallated dialkyl-aminonitriles R2NCH(R )C=N and protected cyanohydrins R CH(C=N)OR (R = SiMe3 or CH(CH3)OEt) as acyl-anion equivalents in organic synthesis has been reviewed by Albright [2]. 

The reactivity of dichlorocarbene towards carbon-carbon triple bonds was systematically investigated by Dehmlov in the sixties, and this work has been reviewed". Dehmlov generated the carbene e.g. by decomposition of sodium trichloroacetate in 1,2-dime thoxy ethane. In additions to ene-yne substrates, sometimes the triple bond, whereas in other cases the double bond accepted the carbene. He observed, for instance, that reaction of the carbene with (E)-l,4-diphenylbutene-l-yne-3 gave the triple-bond addition product 20 exclusively. In reaction with 2-methylpentene-l-yne-3, however, the carbene preferred the double bond, leading to 21. Dichlorocarbene generated from potassium f-butylate and chloroform does not add to electron-poor alkynes, indicating electrophilic behavour of the carbene. 

There has been a review of asymmetric Friedel—Crafts reactions. It has been shown that the rhodium-catalysed reaction of potassium phenyltrifluoroborate with A-tosyl ketimines may lead to products such as (18) with high enantioselectivity. (g) The reaction of A-t-butanesuUinylimino esters with arenes to give products (19) is catalysed by Lewis acids, such as indium triflate, and may lead to enantio-metrically enriched a-glycines. The intramolecular alkylation of hydrogenated 0 tetralins, shown in Scheme 2, using iron(III) or aluminium(III) catalysts yields cis-hexahydrobenzophenanthridines. Formation of a stabilized carbocation intermediate is... 

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