Trityl bromide

Similar reactions occur with all aliphatic halides and the rates of substitution are related to the degree of ionic character of the carbon-halogen bond. For preparation purposes, trityl bromide or propargyl bromide are more convenient than allyl bromide. The compounds obtained are listed in Table XI. They were obtained pure and characterized fully. Zr (allyl) 3Br and Zr(allyl)2Br2 are sufficiently soluble in toluene for polymerizations to be initially homogeneous. Their relative reactivities are listed in Table XI. In all cases hydrogen was used to reduce the molecular weight of the polymer formed. In this respect the polymer derived from Zr (allyl )3Br was more readily modified than that from Zr (allyl) 4, but in order to avoid... 

Bowden and Thomas report that the effect of methyl groups on the conductivity of trityl chloride in sulfur dioxide is in the order p>o>m> none.1 1 The trityl chloride-stannic chloride complex and a whole series of trityl bromides are strong electrolytes in sulfur dioxide.160-152 Benzhydryl chloride, ra-chlorobenzhydryl chloride, and -dimethylbenzhydryl chloride do not conduct in sulfur dioxide. Earlier reports to the contrary may have been due to the use of impure compounds.162 Dimesitylmethyl chloride has also been reported to conduct in sulfur dioxide.163... 

The extent of the ionization produced by a Lewis acid is dependent on the nature of the more inert solvent component as well as on the Lewis acid. A trityl bromide-stannic bromide complex of one to one stoichiometry exists in the form of orange-red crystals, obviously ionic. But as is. always the case with crystalline substances, lattice energy is a very important factor in determining the stability and no quantitative predictions can be made about the behaviour of the same substance in solution. Thus the trityl bromide-stannic bromide system dilute in benzene solution seems to consist largely of free trityl bromide, free stannic bromide, and only a small amount of ion pairs.187 There is not even any very considerable fraction of covalent tfityl bromide-stannic bromide complex in solution. The extent of ion pair and ion formation roughly parallels the dielectric constant of the solvents used (Table V). The more polar solvent either provides a... 

Trimethylene bromide, 20, 25 Trimethylthiourea, 21, 84 Triphenylmethyl chloride, 22, 56 Tritylation of glucose, 22, 56 Trityl bromide, 22, 57 Trityl chloride, 22, 56 6-Trityl-/3-<7-glucose-1,2,3,4-tetra-ACETATE, 22, 56... 

Protection of primary alcohols. This trityl bromide in the presence of AgNO, m DMF reacts selectively with the primary hydroxyl group of carbohydrates and nucleosides. The CPTr ether group is stable to aqueous pyridine and 80% acetic acid, but is selectively cleaved by hydrazine in pyridine-acetic acid. This protecting group is useful in the synthesis of oligoribonucleotides. 

Alcohols r-Butyldiphenylchlorosilane. 2-Benzyloxy-l-propene. Bis(iso-propylthio)boron bromide. /-Butyl me thox-yphenylsilyl bromide. 2,3-Dichloro-5,6-di-cyano-l,4-benzoquinone. Mercury(II) chloride.4,4, 4"-Tris(4,5-dichlorophthalam-ido)trityl bromide. Tetramethylguanidine. Aldehydes Lithium morpolide. Organotitan-ium compounds. 

In detritylation with phosphorus pentabromide, an alkyl bromide, trityl bromide and phosphorus oxybromide are formed. This reaction may be used to locate the position of the trityl group. Phosphorus pentachloride reacts in a similar manner. 

In this experiment the trityl radical is prepared in much the same fashion as Gomberg used, by the reaction of trityl bromide with zinc in the absence of oxygen. The yellow solution will then deliberately be exposed to air to give the peroxide. 

In a small test tube dissolve 100 mg of trityl bromide or chloride in 0.5 mL of toluene. Material prepared in Experiment 2 above may be used it need not be recrystallized. Cap the tube with a septum, insert an empty needle, and flush the tube with nitrogen while shaking the contents. Add 0.2 g of fresh zinc dust as quickly as possible, then flush the tube with nitrogen once more. Shake the tube vigorously for about 10 min, and note the appearance of the reaction mixture. Using a Pasteur pipette transfer the solution, but... 

Trityl esters. Trityl bromide is regarded as superior to trityl chloride for the conversion of metal salts of acids into the trityl esters because it is more reactive and less hygroscopic and can be used with the dry silver, sodium, or potassium salt of the acid. Benzene usually serves satisfactorily as solvent. 

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