Compounds reaction with acidic hydrocarbons

The RjZn compounds react with acidic hydrocarbons to split the original Zn— C bonds and form new ones. The rate depends on hydrocarbon acidity e.g., reactions with triphenylmethane proceed slowly and incompletely. Therefore, it is nearly impossible to obtain organozincs with stoichiometric compositions. More definite results are obtained with 1-alkynes, in which, depending on the molar ratio, one or two organic groups at Zn can be substituted for alkynyl groups ... 

More important are the compounds formed by acidic hydrocarbons such as cyclopentadiene, indene, and acetylenes. These are obtained by reaction with sodium in liquid ammonia or, more conveniently, sodium dispersed in THF, glyme, diglyme, or dimethylformamide (DMF). 

The reaction of metal hydrides MH2 with acidic hydrocarbons seems an attractive way to prepare the target compound since a commercially available metal source can be utilized. Moreover, the formation of only gaseous byproducts ensures a facile work-up (equation 13). However, only few compounds have been prepared using this route owing to the low reactivity of the hydrides caused by their polymeric, insoluble nature. Moreover, the unreliable purity of the commercial hydrides poses significant problems. As such, rather acidic ligands and enforced reaction conditions are required for the reaction to proceed. 

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 Reaction of Acidic Hydrocarbons with Sn-O and Sn-N Bonded Compounds... 

HYDROXYDE de SODIUM (French) (1310-73-2) A strong base. Reacts with water, evolving heat and corrosive fumes. Violent reaction with acids, halogenated hydrocarbons, nitrogen-containing compounds, organic halogens, 4-chloro-2-methylphenol, 2,2-dichloro-... 

The high reactivity of benzynes as dienophiles in Diels-Alder reactions has also been observed in reactions with aromatic hydrocarbons, a class of compounds usually considered as inert as dienes. In a two-step synthesis of triptycene di- and tetracarboxylic acids, arynes generated in situ from anthranUic adds 158 cydized with anthracenes 159 affording di- or tetramethyltriptycenes 160 in 41-69% yields (Scheme 12.47) [85], Acids 161 were obtained after subsequent oxidation of the cycloadducts 160 with potassium permanganate. 

The synthesis of A/-acyl-a-chloroglycine and its use in the preparation of other a-substituted glycines has been described.N-Acylhemiaminals, prepared from glyoxylic acid and amides, carbamates, or ureas, can be converted into N-acyl-a-arylglycines by reaction with aromatic hydrocarbons in sulphuric acid. The same type of hemiaminals may be converted into N-acyl-y-keto-a-amino-acids by reactions with 1,3-dicarbonyl compounds again in the presence of concentrated sulphuric acid. °°... 

Unlike aliphatic hydrocarbons, aromatic hydrocarbons can be sul-phonated and nitrated they also form characteristic molecular compounds with picric acid, styphnic acid and 1 3 5-trinitrobenzene. Many of the reactions of aromatic hydrocarbons will be evident from the following discussion of crystalline derivatives suitable for their characterisation. 

The formation of the above anions ("enolate type) depend on equilibria between the carbon compounds, the base, and the solvent. To ensure a substantial concentration of the anionic synthons in solution the pA" of both the conjugated acid of the base and of the solvent must be higher than the pAT -value of the carbon compound. Alkali hydroxides in water (p/T, 16), alkoxides in the corresponding alcohols (pAT, 20), sodium amide in liquid ammonia (pATj 35), dimsyl sodium in dimethyl sulfoxide (pAT, = 35), sodium hydride, lithium amides, or lithium alkyls in ether or hydrocarbon solvents (pAT, > 40) are common combinations used in synthesis. Sometimes the bases (e.g. methoxides, amides, lithium alkyls) react as nucleophiles, in other words they do not abstract a proton, but their anion undergoes addition and substitution reactions with the carbon compound. If such is the case, sterically hindered bases are employed. A few examples are given below (H.O. House, 1972 I. Kuwajima, 1976). 

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