TRIPHENYLMETHYL CHLORIDES

If triphenylmethyl chloride in ether is treated with sodium, a yellow colour is produced due to the presence of the anionic spiecies PhsC". Alternatively, if triphenylmethyl chloride is treated with silver perchlorate in a solvent such as THF, the triphenylmethyl cation is obtained. More conveniently, triphenylmethyl salts, PhsC X", can be obtained as orange-red crystalline solids from the action of the appropriate strong acid on triphenylcarbinol in ethanoic or propanoic anhydride solution. The perchlorate, fluoroborate and hexafluoro-phosphate salts are most commonly used for hydride ion abstraction from organic compounds (e.g. cycloheptatriene gives tropylium salts). The salts are rather easily hydrolysed to triphenylcarbinol. 

Cesium forms simple alkyl and aryl compounds that are similar to those of the other alkah metals (6). They are colorless, sohd, amorphous, nonvolatile, and insoluble, except by decomposition, in most solvents except diethylzinc. As a result of exceptional reactivity, cesium aryls should be effective in alkylations wherever other alkaline alkyls or Grignard reagents have failed (see Grignard reactions). Cesium reacts with hydrocarbons in which the activity of a C—H link is increased by attachment to the carbon atom of doubly linked or aromatic radicals. A brown, sohd addition product is formed when cesium reacts with ethylene, and a very reactive dark red powder, triphenylmethylcesium [76-83-5] (C H )2CCs, is formed by the reaction of cesium amalgam and a solution of triphenylmethyl chloride in anhydrous ether. 

C5H5N CPh3BF4, CH3CN, Pyr, 60-70°, 75-90% yield. Triphenylmethyl ethers can be prepared more readily with triphenylmethylpyridinium fluo-roborate than with triphenylmethyl chloride-pyridine. 

Triphenylmethyl chloride (trityl chloride) [76-83-5] M 278.9, m 111-112 . Crystd from isooctane. Also crystd from 5 parts of pet ether (b 90-100°) and 1 part of acetyl chloride using 1.8g of solvent per g of chloride. Dried in a desiccator over soda lime and paraffin wax. [Org Synth Coll Vol 111 841 1955 Thomas and Rochow J Am Chem Soc 79 1843 1957 Moisei et al. J Am Chem Soc 108 4706 1986.]... 

As previously discussed, ethyl chlorocarbonate reacts rapidly and selectively with an equatorial 3-hydroxyl group to give the corresponding cathylate. Trityl ethers, usually employed as a selective protecting group for primary hydroxyls, can be prepared from A -3j3-ols by heating with triphenylmethyl chloride in pyridine, and from 5a-3 -alcohols by more prolonged heat-... 

If (A i[X ]/A 2[Y ]) is not much smaller than unity, then as the substitution reaction proceeds, the increase in [X ] will increase the denominator of Eq. (8-65), slowing the reaction and causing deviation from simple first-order kinetics. This mass-law or common-ion effect is characteristic of an S l process, although, as already seen, it is not a necessary condition. The common-ion effect (also called external return) occurs only with the common ion and must be distinguished from a general kinetic salt effect, which will operate with any ion. An example is provided by the hydrolysis of triphenylmethyl chloride (trityl chloride) the addition of 0.01 M NaCl decreased the rate by fourfold. The solvolysis rate of diphenylmethyl chloride in 80% aqueous acetone was decreased by LiCl but increased by LiBr. ° The 5 2 mechanism will also yield first-order kinetics in a solvolysis reaction, but it should not be susceptible to a common-ion rate inhibition. 

P-p-C H4Ph2CCl, Pyr, 25°, 5 days, 90%, where P = styrene-divinyl-benzene polymer. Triarylmethyl ethers of primary hydroxyl groups in glucopyranosides have been prepared using a polymeric form of triphenylmethyl chloride. Although the yields are not Improved, the workup is simplified. 

The kinetics of alkylation by triphenylmethyl compounds have been studied. Hart and Cassis353 found that the alkylation of phenol and o-cresol by triphenylmethyl chloride in o-dichlorobenzene gave non-linear kinetic plots which were, however, rendered linear by presaturation of the reaction mixture with hydrogen chloride, precise third-order kinetics, equation (182)... 

An example of first-order kinetics is the hydrolysis of triphenylmethyl chloride,1-... 

The hydrolysis of triphenylmethyl chloride follows first-order kinetics. The left panel shows the growth of (H J, a product (filled squares), and the exponential decrease in (PhiCCI], (open squares). The second and third panels show linearized forms, with [Ph,CCl], and [Ph CCl]o/tPhiCCI], being displayed on logarithmic scales. Each line is the least-squares fit to the indicated function. 

MEMED has been used to study the hydrolysis of triphenylmethyl chloride (TPMCl) in a... 

Sodium triphenylmethane treatment of triphenylmethyl chloride with an excess of sodium in benzene leads, via the triphenylmethyl radical (Gomberg, 1900), to triphenylmethyl sodium ... 

The importance of establishing the correct structure of the reaction product is best illustrated by the confusion that can result when this has been assumed, wrongly, as self-evident, or established erroneously. Thus the yellow triphenylmethyl radical (3, cf. p. 300), obtained from the action of silver on triphenylmethyl chloride in 1900, readily forms a colourless dimer (m.w. = 486) which was—reasonably enough—assumed to be hexaphenylethane (4) with thirty aromatic ... 

Treatment of triphenylmethyl chloride with silver gave not the expected hydrocarbon but an oxygen-containing compound later found to be the peroxide. The reaction run in an inert atmosphere did give a hydrocarbon, but one with unusual properties. It reacted rapidly with oxygen, chlorine, and bromine, and was quite different from tetra-phenylmethane or what was expected of hexaphenylethane. Gomberg... 

Conductimetric Dissociation Constants of Some Substituted Triphenylmethyl Chlorides in Sulfur Dioxide at 0°... 

Triphenylcarbinol in sulfuric acid solution has a spectrum indicating the presence of the same carbonium ion responsible for the conductivity of triphenylmethyl chloride in liquid sulfur dioxide.171 In confirmation of this the freezing point depression is four times that of substances dissolving to give only one mole of particles per mole of dissolved substance.171-173... 

The degrees of ionization of triphenylmethyl chloride, di-methoxybenzhydryl chloride, and dimesitylmethyl chloride in liquid... 

Catalysis (initiation) by a free radical, on the other hand, is fairly conclusive evidence of a radical reaction, provided it is known that the catalyst is indeed a free radical and that it does not have pronounced polar properties as well. Many classes of compound once thought to decompose exclusively into ions or exclusively into radicals are now known to do both. Peroxides are one well-known example, AT-halo-amides are another. Catalysis by benzoyl peroxide probably does indicate a radical reaction since there is no evidence that this particular peroxide tends to give ions even under the most favorable conditions. But many other peroxides are known to decompose into ions, or at least ion pairs, as well as into radicals. The decomposition of azo compounds can also be either radical or ionic, the dialkyl azo compounds tending to give radicals, the diazonium compounds either radicals or ions. Catalysis by a borderline example of an azo compound would therefore be dubious evidence of either kind of mechanism. The initiation of the polymerization of octyl vinyl ether by triphenylmethyl chloride in polar... 

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