Alcohols, allylic peroxides

Depending on the choice of transfer agent, mono- or di-cnd-functional polymers may be produced. Addition-fragmentation transfer agents such as functional allyl sulfides (Scheme 7.16), benzyl ethers and macromonomers have application in this context (Section 6.2.3).212 216 The synthesis of PEG-block copolymers by making use of PEO functional allyl peroxides (and other transfer agents has been described by Businelli et al. Boutevin et al. have described the telomerization of unsaturated alcohols with mercaptoethanol or dithiols to produce telechelic diols in high yield. 

Heteropoly acids can be synergistically combined with phase-transfer catalysis in the so-called Ishii-Venturello chemistry for oxidation reactions such as oxidation of alcohols, allyl alcohols, alkenes, alkynes, P-unsaturated acids, vic-diols, phenol, and amines with hydrogen peroxide (Mizuno et al., 1994). Recent examples include the epoxidations of alkyl undecylenates (Yadav and Satoskar, 1997) and. styrene (Yadav and Pujari, 2000). 

Usually the allylic peroxides are not the final products but they are reduced to allylic alcohols as in the synthesis of E-5-cyclodecenone (6.14)620). 

Oxidation of allylic alcohols with singlet oxygen has been used as a route to prepare allylic peroxides in a stereoselective fashion (equation 46)189. 

Fig. 18. Product formation during the oxidation of propane in the absence of pic d arret. Initial temperature = 430 °C initial pressure of propane = 60 torr initial pressure of oxygen = 240 torr. (b) Left ordinate +, methyl alcohol. Right ordinate X, isopropyl alcohol , ethyl alcohol o, n-propyl alcohol , allyl alcohol (xO.5). (c) Left ordinate +, hydrogen peroxide , formaldehyde. Right ordinate x, total aldehydes, (d) +, propene , methane , ethylene x, ethane. (From ref. 147.) References pp. 361—367...

The reaction of allyl alcohol, 2-methyl allyl alcohol and crotyl alcohol (trans cis= 4.45 1) were reacted with hydrogen peroxide at 30 °C using methanol assolvent, and the results are shown in Figures 1-3. It is apparent that the order of reactivity is cis-crotyl alcohol > trans-crotyl alcohol > allyl alcohol > 2 methylallyl alcohol. The latter alcohol was not particularly reactive and this indicates that substition at the 2-position inhibits the reaction significantly. 

In 1898 Solomina [1] reported that sulfur dioxide reacted with allyl alcohol, allyl methyl ether, and allyl ethyl ether [1]. Solomina reported that carboxyl, halide, and ester groups inhibited the reaction [1]. In 1935 Ryden and Marvel [26] reported that sulfur dioxide did not copolymerize with allyl cyanide or 2-allyl-/i-cresol when peroxide-paraldehyde was used but did polymerize when ascaridole was added [62]. In a later publication Kharasch and Steinfeld reported that allyl chloride copolymerized with sulfur dioxide in the presence of ascaridole and aqueous hydrochloric acid [63]. 

Oxidative Methods.—Oxidation of Alcohols. Benzoyl peroxide catalysed by nickel(ii) bromide gives high yields of aldehydes and ketones from the corresponding alcohols. Similar yields are obtained with t-butyl hydroperoxide catalysed by diaryl diselenides, a method particularly recommended for benzylic or allylic alcohols. Ketones are obtained from secondary alcohols using hydrogen peroxide catalysed by molybdenum or tungsten peroxo-complexes/ and nickel peroxide has been employed to prepare a-allenic aldehydes and ketones from allenic alcohols. ... 

A review describes the asymmetric epoxidation of allylic alcohols,369 another the role of metal oporphyrins in oxidation reactions.370 jhe TiiOPrMi, catalysed self-epoxidation of allylic peroxides proceeds via an intermolecular mechanism.371 Racemic allyl alcohols can be resolved by asymmetric epoxidation (eq.35).372 a Pd(II)/Mn02/benzoquinone system catalyses the oxidative ring-closure of 1,5-hexadienes (eq.36).373 propenyl phenols are oxidatively degraded to aryl aldehydes and MeCHO in the presence of Co Schiff-base catalysts.374 An Oppenauer-type oxidation with Cp2ZrH2/cyclohexanone converts primary alcohols selectively into aldehydes.375 co macrocycles catalyse the oxidation of aryl liydrazones to diazo compounds in high yields.376 similar Co complexes under CO oxidise primary amines to azo compounds.377 Arene Os complexes in the presence of base convert aldehydes and water slowly into carboxylic acids and H2.378... 

Sharpless advanced this notion through using a metal-based epoxidation catalyst (Scheme 4.18) [44]. This approach took advantage of the capacity of VO(acac)j to coordinate simultaneously to alcohols and peroxides and promote regioselective epoxidations of allylic and homoal-lylic alcohols with iBuOOH as the oxidant, as shown by the conversion of 87 to 88. This approach also provides stereoselectivity, as shown by the transformation of 89 to 90 in which the hydroxyl group directs a yn-oxidation of the alkene. This procedure is selective because alkyl peroxides generally do not epoxidize alkenes but can be activated by coordination to the alcohol-coordinated vanadium Lewis acid. 

Allyl alcohol [107-18-6] M 58.1, b 98°, d4 0,857, no 1.4134. Can be dried with K2CO3 or CaSOa, or by azeotropic distn with benzene followed by distn under nitrogen. It is difficult to obtain peroxide free. Also reflux with magnesium and fractionally distd [Hands and Norman Ind Chem 21 307 1945],... 

Nickel peroxide is a solid, insoluble oxidant prepared by reaction of nickel (II) salts with hypochlorite or ozone in aqueous alkaline solution. This reagent when used in nonpolar medium is similar to, but more reactive than, activated manganese dioxide in selectively oxidizing allylic or acetylenic alcohols. It also reacts rapidly with amines, phenols, hydrazones and sulfides so that selective oxidation of allylic alcohols in the presence of these functionalities may not be possible. In basic media the oxidizing power of nickel peroxide is increased and saturated primary alcohols can be oxidized directly to carboxylic acids. In the presence of ammonia at —20°, primary allylic alcohols give amides while at elevated temperatures nitriles are formed. At elevated temperatures efficient cleavage of a-glycols, a-ketols... 

The mechanism for such a process was explained in terms of a structure as depicted in Figure 6.5. The allylic alcohol and the alkyl hydroperoxide are incorporated into the vanadium coordination sphere and the oxygen transfer from the peroxide to the olefin takes place in an intramolecular fashion (as described above for titanium tartrate catalyst) [30, 32]. 

Lewis acids such as SnCl4 also catalyze the reaction, in which case the species that adds to the alkenes is H2C —O— SnC. Montmorillonite KIO clay containing zinc(IV) has been used to promote the reaction. The reaction can also be catalyzed by peroxides, in which case the mechanism is probably a free-radical one. Other transition metal complexes can be used to form allylic alcohols. A typical example is. ... 

When preparing allyl oxide according to this method, a violent detonation interrupted the operation. It was explained by the alcohol polymerisation catalysed by sulphuric acid. There was a less convincing explanation, which is peroxidation in the allylic position of alcohol or the ether obtained. Indeed, there should have been prolonged storage for this peroxidation. 

Hexafluoroacetone and hydrogen peroxide in buffered aqueous solution can epoxidize alkenes and allylic alcohols.101 N, Af-Dialkylpiperidin-4-one salts are also good catalysts for epoxidation.102 The polar effect of the quaternary nitrogen enhances the... 

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