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Phenylboronic acid or benzeneboronic acid, abbreviated as PhB(OH) 2 where Ph is the phenyl group C 6 H 5 - and B(OH) 2 is a boronic acid containing a phenyl substituent and two hydroxyl groups attached to boron. Phenylboronic acid is a white powder and is commonly used in organic synthesis.
The typical reaction conditions used today were developed by G. A. Kraus. [2] [3] H.W. Pinnick later demonstrated that these conditions could be applied to oxidize α,β-unsaturated aldehydes. [4] There exist many different reactions to oxidize aldehydes, but only a few are amenable to a broad range of functional groups.
Most primary and secondary perfluoroalcohols are unstable, for example trifluoromethanol eliminates hydrogen fluoride, forming carbonyl fluoride. [2] This reaction is reversible. [3] CF 3 OH → COF 2 + HF. Stable perfluorinated alcohols include nonafluoro-tert-butyl alcohol ((CF 3) 3 COH) and pentafluorophenol (C 6 F 5 OH).
Such reactions give alkenes in the case of vicinal alkyl dihalides: [2] R 2 C(X)C(X)R 2 + M → R 2 C=CR 2 + MX 2. Most desirable from the perspective of remediation are dehalogenations by hydrogenolysis, i.e. the replacement of a C−X bond by a C−H bond. Such reactions are amenable to catalysis: R−X + H 2 → R−H + HX
According to the procedure, solid [PhN 2]BF 4 is heated with a flame to initiate an exothermic reaction, which also affords boron trifluoride and nitrogen gas. Product PhF and BF 3 are readily separated because of their differing boiling points. [2] The technical synthesis is by the reaction of cyclopentadiene with difluorocarbene.
The reaction is initiated by addition of a catalytic amount of PBr 3, after which one molar equivalent of Br 2 is added. PBr 3 converts the carboxylic OH to the acyl bromide. The acyl bromide tautomerizes to an enol, which reacts with the Br 2 to brominate at the α position.In neutral to slightly acidic aqueous solution, hydrolysis of the α-bromo acyl bromide occurs spontaneously, yielding ...
An example involves the conversion of the ethyl ester of 5-bromovaleric acid to the iodide: [4] EtO 2 C(CH 2) 4 Br + NaI → EtO 2 C(CH 2) 4 I + NaBr. Potassium fluoride is used for the conversion of chlorocarbons into fluorocarbons. [5] Such reactions usually employ polar solvents such as dimethyl formamide, ethylene glycol, and dimethyl ...
Bromoform was discovered in 1832 by Löwig who distilled a mixture of bromal and potassium hydroxide, as analogous to preparation of chloroform from chloral. [5]Bromoform can be prepared by the haloform reaction using acetone and sodium hypobromite, by the electrolysis of potassium bromide in ethanol, or by treating chloroform with aluminium bromide.