Alcohols from peroxides

Free cydohexene from peroxides by treating it with a saturated solution of sodium bisulphite, separate, dry and distil collect the fraction, b.p. 81-83°. Mix 8 -2 g. of cycZohexene with 55 ml. of the reagent, add a solution of 15 mg. of osmium tetroxide in anhydrous butyl alcohol and cool the mixture to 0°. Allow to stand overnight, by which time the initial orange colouration will have disappeared. Remove the solvent and unused cydohexene by distillation at atmospheric pressure and fractionate the residue under reduced pressure. Collect the fraction of b.p. 120-140°/15 mm. this solidifies almost immediately. Recrystallise from ethyl acetate The yield of pure cis-l 2 cydohexanediol, m.p. 96°, is 5 0 g. 

The hydrides can also be used to form primary alcohols from either terminal or internal olefins. The olefin and hydride form an alkenyl zirconium, Cp2ZrRCl, which is oxidized to the alcohol. Protonic oxidizing agents such as peroxides and peracids form the alcohol direcdy, but dry oxygen may also be used to form the alkoxide which can be hydrolyzed (234). 

Isopropyl Ether. Isopropyl ether is manufactured by the dehydration of isopropyl alcohol with sulfuric acid. It is obtained in large quantities as a by-product in the manufacture of isopropyl alcohol from propylene by the sulfuric acid process, very similar to the production of ethyl ether from ethylene. Isopropyl ether is of moderate importance as an industrial solvent, since its boiling point Hes between that of ethyl ether and acetone. Isopropyl ether very readily forms hazardous peroxides and hydroperoxides, much more so than other ethers. However, this tendency can be controlled with commercial antioxidant additives. Therefore, it is also being promoted as another possible ether to be used in gasoline (33). 

The preparation of neopentyl alcohol from diisobutylene herein described represents an example of acid-catalyzed addition of hydrogen peroxide to a branched olefin, followed by an acid-catalyzed rearrangement of the tertiary hydroperoxide formed. In addition to neopentyl alcohol, there are formed acetone and also small amounts of methanol and methyl neopentyl ketone by an alternative rearrangement of the hydroperoxide. 

Lithium aluminium hydride Higuchi and co-workers100 introduced it as a titrant, usually in tetrahydrofuran (previously liberated from peroxide), for the titration of alcohols and phenols according to the overall reaction... 

The experimental data on the reactions of ketyl radicals with hydrogen and benzoyl peroxides were analyzed within the framework of IPM [68]. The elementary step was treated as a reaction with the dissociation of the O—H bond of the ketyl radical and formation of the same bond in acid (from acyl peroxide), alcohol (from alkyl peroxide), and water (from hydrogen peroxide). The hydroperoxyl radical also possesses the reducing activity and reacts with hydrogen peroxide by the reaction... 

In the absence of an initiator, alcohols are oxidized with self-acceleration [7-9]. As in the oxidation of hydrocarbons, the increase in the reaction rate is due to the formation of peroxides initiating the chains. The kinetics of radical formation from peroxides was studied for the oxidation of isopropyl alcohol [58] and cyclohexanol [59,60]. 

Data from Ref. 1 and private communication BuOH9OOH represents sum of alcohol and peroxide RH consumption calculated from products c.l. represents chain length = [RH consumed] / [2(ButOt) consumed]... 

Directed asymmetric reduction of a ketone has been brought about by the use of an intramolecular homochiral boronate ester250. The latter was readily introduced at a hydroxyl group in the molecule and has allowed the production of the enantiomeric alcohol, from the ketone by use of BH3-complex as the reductant (equation 64). The boronate ester may be readily removed by treatment with hydrogen peroxide-sodium hydroxide, using standard methodology. Other similar reductions have also been reported251-253. 

The alcohol is purified by shaking with aqueous potassium hydroxide and extracting with diethyl ether that has been freed from peroxides with silver nitrate and sodium hydroxide. After being washed, the extract is treated with saturated sodium hydrogen sulphide solution, filtered, washed and dried over potassium carbonate. After removal of the ether, the alcohol is distilled under reduced pressure and the middle fraction dried over lime that has been burned in an atmosphere of nitrogen. 

Reaction with trialkylboranes. Lane and Brown in 1971 reported a simple procedure for synthesis of highly substituted alcohols from trialkylboranes. For example, bromination of triethylboranc (1) under irradiation in the presence of water followed by oxidation with alkaline hydrogen peroxide gives 3-methyl-3-pentanol (2) in 88% yield. The reaction involves as the first step free-radical bromination in the a-position... 

Synthesis of secondary alcohols from 1-aOcynes.2 Dihydroboration at room temperature of a terminal alkyne with either (1) or 9-BBN gives a 1,1-diborylalkane (3) this is treated at 0-5° with I eq. of methyllithium in ether. The product (4) rearranges to (5). An alkyl halide (100% excess) is then added, and the resultant secondary organo-borane (6) is oxidized with alkaline hydrogen peroxide. Secondary alcohols (7) are obtained in 70-85% yield. 

The establishment of natural artemisia alcohol from sage as the (5)-isomer was announced by Zydowsky and Hill in 1982, and an elegant synthesis of both enantiomers by H.C. Brown utilizes the chiral borane 219, which contains a prenyl group. Reaction of the illustrated enantiomer with senecio aldehyde (84) gave the addition product from which (- )-(S)-artemisia alcohol [(- )-209] was obtained after alkaline peroxide oxidation in 96% ee. ... 

Preparation of tertiary alcohols from the corresponding hydrocarbons can be realized in some cases also by use of hydrogen peroxide or its derivatives. E.g., 10-hydroxy-10-methyl-9-anthrone is obtained from 10-methyl-9-anthrone by means of alkaline hydrogen peroxide solution.228... 

In the absence of initiators, alcohol oxidation is self-accelerating (see Sect. 2.1) due to the formation of peroxides, as in the case of hydrocarbon oxidation. The mechanism of free radical formation from peroxides was studied for 2-propanol [25] and cyclohexanol [32,56], The kinetics of hydrogen peroxide formation obeys the equation [25]... 

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