Benzyl alcohol bromine

A -Bromosuccinimide has been used in combination with benzyl alcohol for the bromination of ketones ... 

Displacement of bromine on phenacyl halide with imidazole gives Reduction with sodium borohydride followed by displacement with 2,6-dichloro-benzyl alcohol in HMPA then produces antifungal orconazole (37). ... 

Similarly, Dakka and Sasson (ref. 26) showed that benzylic alcohols could be selectively oxidized to the corresponding aromatic aldehydes using HBr/H202 as the oxidant (Fig. 23). The reaction was not successful with electron-rich aromatics which underwent competing nuclear bromination. 

Synthetic routes that access appropriately substituted thienobenzazepines are also quite important for medicinal chemistry stracture activity relationship studies, and many involve similar bond connectivity strategies. One notable example employs the use of conunercially available 4-methyl-3-nitrophenol (Scheme 6.3). Methylation of the phenol followed by bromination, hydrolysis, and oxidation of the benzylic alcohol afforded aldehyde 9 in quantitative yield. Treatment of this aldehyde with 5-lithio-2-methylthiophene provided, after dehydroxylation, nitro intermediate A in good overall yield. Reduction of the nitro functionality and treatment with phosgene presented the corresponding isocyanide which upon cychzation using aluminum trichloride in a Friedel-Crafts fashion afforded the... 

Organolithium reagent 35 was added to aldehyde 31 (Scheme 7.6) to obtain alcohol 36 as an inconsequential 1 1 mixture of diastereomers. The benzylic alcohol was removed using a Barton two-step radical deoxygenation protocol, followed by electrophilic aromatic bromination to provide the desired coupling partner 37. 

Miscellaneous The treatment of allyl 1-bromo-2-naphthyl ether 43 with f-BuLi affords benzyl alcohol 44 via a sequential reaction consisting of bromine-lithium exchange, and anion translocation, followed by a [1,2]-Wittig rearrangement (equation 23). ... 

Very recently, Hu et al. claimed to have discovered a convenient procedure for the aerobic oxidation of primary and secondary alcohols utilizing a TEMPO based catalyst system free of any transition metal co-catalyst (21). These authors employed a mixture of TEMPO (1 mol%), sodium nitrite (4-8 mol%) and bromine (4 mol%) as an active catalyst system. The oxidation took place at temperatures between 80-100 °C and at air pressure of 4 bars. However, this process was only successful with activated alcohols. With benzyl alcohol, quantitative conversion to benzaldehyde was achieved after a 1-2 hour reaction. With non-activated aliphatic alcohols (such as 1-octanol) or cyclic alcohols (cyclohexanol), the air pressure needed to be raised to 9 bar and a 4-5 hour of reaction was necessary to reach complete conversion. Unfortunately, this new oxidation procedure also depends on the use of dichloromethane as a solvent. In addition, the elemental bromine used as a cocatalyst is rather difficult to handle on a technical scale because of its high vapor pressure, toxicity and severe corrosion problems. Other disadvantages of this system are the rather low substrate concentration in the solvent and the observed formation of bromination by-products. 

A new ionic liquid, l-butyl-3-methylimidazolium tribromide can act as an oxidizing agent to convert alcohols to aldehydes and ketones.338 In the case of benzyl alcohols and diols, [Bmim][Br3] combines oxidizing and brominating properties in a one-pot synthesis of /3-bromoethyl esters. 

Hydrolysis of the benzylic bromide gives the corresponding benzylic alcohol. The bromine that is directly attached to the naphthalene ring does not react under these conditions. 

However, benzyl alcohols can be converted to benzaldehydes even in the dark.208 It has been reported that catalytic amounts of HBr may be used for this reaction.209 Primary aliphatic alcohols give rise to carboxylic esters. Catalytic amounts of bromine itself have been used, instead of HBr in the oxidation of lactate esters to pyruvates.210... 

Benzyl bromide may be prepared by the action of hydrobromic acid on benzyl alcohol or by the action of bromine on toluene. Stephen has worked out a method which consists in treating dibromomethyl ether with benzene ... 

The bisglyoximato nickel and palladium complexes are prepared via direct reaction of bromine, iodine, or iodine monobromide in solvents such as dichloromethane, o-dichlorobenzene, and benzyl alcohol. Slow cooling leads to the formation of the largest crystals . ... 

Benzoyl Chloride Benzyl Alcohol Borax Boric Acid Bromine Butyl Acetate Butyl Methacrylate Butylamlne Calcium Chloride... 

Derivation (1) Bromination of toluene, (2) interaction of benzyl alcohol and hydrobromic acid. 

Several new procedures for the selective oxidation of secondary alcohols in the presence of primary alcohols have appeared. Distannoxane-bromine, a neutral reagent, efficiently oxidizes secondary or benzylic alcohols to ketones in the presence of primary alochols.62 Trialkyltin alkoxides and bromine oxidize both primary and secondary alcohols.63 Woelm W-200, neutral, dehydrated alumina oxidizes secondary alcohols to ketones in the presence of primary alcohols with trichloroacetaldehyde as the hydride acceptor.6 The reverse reduction process had previously been reported. Oxidation of triphenylmethyl ethers of primary, secondary diols with triphenyl carbenium salts proceeds only at the secondary positions.65... 

The competitive aromatic bromination has not been observed in all of the cases tested. It is also noteworthy that prolonged reaction times were required in cases of benzylic alcohols with electron-withdrawing groups on the aromatic rings. This result can be rationalized by the sluggish formation of hypobromite reaction intermediates in cases of the less reactive electron-deficient benzylic alcohols. 

In the presence of bromate a nearly constant Br2-concentration and a pH of ca. 2.5 is maintained. Under these Conditions bromine substitution can be kept low, even in the temp, range between 50 and 80°. Upon oxidation prim, aliphatic alcohols give esters, sec. alcohols give ketones, and benzyl alcohol gives mainly benzaldehyde.—E n-Butyl alcohol with KBrOs, Br2 or HBr, and water first kept at 40-50° for ea. 3 hrs. until the color of the Br2 begins to disappear, then the temp, raised slowly to 70°, finally to 100 —n-butyl n-butyrate. Y 82%. (F. e. s. L. Farkas and O. Seh chter, Am. Soc. 71, 2827 (1949).)... 

Bromination might well oxidise the reactive benzylic alcohol in (5) so an acetal protecting group is added. This could be removed to give (4), but as a protecting group was needed later in the synthesis, it was left in place. 

When a-vinylbenzyl alcohol reacts with bromine in dry CHC13, CC14, or CS2, (l,2,3-tribromopropyl)benzene is formed exclusively however, carrying out the reaction with pyridine hydrobromide dibromide in glacial acetic acid at 12-15° leads mainly to addition of bromine, which results in <%-(l,2-dibromo-ethyl)benzyl alcohol.70 Analogously, but without a solvent, allyl alcohol gives 2,3-dibromo-1 -propanol.71... 

For addition of HOBr the unsaturated compound is usually stirred for some hours at room temperature with bromine water, then the excess of hypobromite is removed by sodium hydrogen sulfite, the solution is saturated with salt, and the bromohydrin is shaken out of the aqueous phase into ether or CHC13. A cold solution of hypobromite obtained from bromine and alkali carbonate may be used in place of bromine water.281 The tendency of styrene to bromohydrin formation is so great that -(bromomethyl)benzyl alcohol is obtained in excellent yield even in hot water (60-90°) by use of a bromine solution in the presence of KBr.261 282... 

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