Lithium triphenylmethane

Finally, mention can be made of the more exceptional titrants for inert media, such as sodium triphenylmethane, lithium aluminium hydride and lithium aluminium amide. 

Non-aromatic organolithium compounds can be prepared by transmetallation of resin-bound stannanes [25] or by deprotonation of alkynes [26], triphenylmethane [27], or other resin-bound C II acidic compounds with lithium amides or similar bases (Figure 4.3). The reaction of polystyrene-bound trialkylboranes with diethylzinc yields resin-bound alkylzinc derivatives [28]. 

Juaristi, E. Martinez-Richa, A. Garcia-Rivera, A. Cruz-Sanchez, J. S. Use of 4-biphenylyl-mefhanol, 4-biphenylylacetic acid, and 4-biphenylcarboxylic add/triphenylmethane as indicators in the titration of lithium alkyls. Study of the dianion of 4-biphenylylmethanol. /. Org. Chem. 1983, 48, 2603-2606. 

Triphenylmethane can be used as an indicator3 for lithium n-butyl and s-butylzincates, but not for t-... 

The triphenylmethyl carbanion, the trityl anion, can be generated by the reaction of triphenylmethane with the very powerful base, n-butyllithium. The reaction generates the blood-red lithium triphenylmethide and butane. The triphenylmethyl anion reacts much as a Grignard reagent does. In the present experiment it reacts with carbon dioxide to give triphenylacetic acid after acidification. Avoid an excess of n-butyllithium on reaction with carbon dioxide, it gives the vile-smelling pentanoic acid. 

House and Trost prepared an approximately IM solution of this reagent in 1,2-dimethoxyethane for use in an extensive study of compositions of enolate anions from ketones and enol acetates as follows. The solvent was removed from 15 ml. of a 1 Af ethereal solution of methyllithium under reduced pressure, and the residual solid was dissolved in 15 ml. of 1,2-dimethoxyethane. Triphenylmethane (18.3 mmoles) was added, and the mixture stirred under nitrogen until a test for methyl-lithium was negative. Reaction of an enol acetate with trityllithium can then be carried out as a titration and stopped when the solution is pale pink. 

Tomboulian and Stehower5 prepared this reagent in quantitative yield by metala-tion of triphenylmethane with n-butyllithium (50-150% excess) in THF or tetra-hydro-2-methylfurane as solvent. They recommend that the n-butyllithium be prepared from lithium and n-butyl chloride in the reaction solvent. If the exchange is carried out at room temperature, excess butyllithium is rapidly consumed by reaction with tetrahydrofurane. With tetrahydropyrane as solvent, trityllithium was found to react with benzophenonc to form p-(diphenylmethyl)diphenylhydroxymethyl-benzene ... 

The authors speculate that the stereochemical divergence may be related to the ability of the electrophile to coordinate with the lithium, coupled with the presence or absence of a low-lying LUMO. Curiously, protonation by methanol proceeds with retention whereas protonation with either acetic acid or triphenyl methane proceeds with inversion. The authors speculate that, in acetic acid, protonation of the TMEDA nitrogen and internal return (c/. Schemes 3.2 and 3.24) may occur instead of direct protonation [184]. Presumably, direct protonation is the only mechanistic course with weak acids such as methanol and triphenylmethane and steric effects dictate inversion for the latter. Hoppe also noted that the enantiomeric purity of the products also depended on the solvent. In THF, the products were nearly racemic, and the enantiomeric purity of several of the other alkylation products was variable in solvents such as ether and pentane. This variability is due, at least in part, to the degree of covalency of the C-Li bond. In donor solvents such as THF, racemization is more facile. 

To examine the distribution of acidic C-H sites in PSOC 1197, derived in part from polynuclear hydroaromatic compounds, the pH 12 O-methyl coal was treated for 68 h at 0 °C, in separate experiments, with an excess of the conjugate bases of 9-phenylfluorene (pKa 18.5), fluorene (pKa 22), and triphenylmethane (pKa 31) as their lithium salts (BLi) THF was used as the solvent ... 

It is claimed that many types of reactions can be performed more easily with multiple polymers. To avoid undesirable side reactions two reacting species can be used with each attached to a different polymer. Such polymer-bound reactants can coexist in the same reaction vessel without interacting. An example is the preparation of benzoyl acetonitrile by Patchomik and coworkers. Molecules of triphenylmethane lithium, attached to polystyrene supports, were combined with also immobilized o-nitrophenol. The < -nitrophenols were prereacted with benzoyl chloride. The two species were combined and acetonitrile molecules containing acidic hydrogens were introduced into the reaction mixture. This resulted in hydrogens being abstracted from the introduced molecules and formation of short-lived carbanions ... 

Alkali-metal hydi oearbon derivatives react with fonnaldeh i de in the same manner as the Grignard compounds. Schlenk and Ochs report the formation of triphenylmethylcarbinol by reaction of formaldehyde and sodium triphenylmethane. The allyhe reaiTangement also takes place when lithium benzyl is reacted with formaldehyde gas, orfcho-tolylcarbinol being obtained. Sodium acetylides react normally giving acetylenic... 

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