Aromatic alcohols, formation

The preparation of ketones proceeds conveniently by reaction of imidazolides with organomagnesium reagents, as shown in Table 14-6 for several examples of purely aromatic, aromatic-aliphatic, and purely aliphatic ketones. The yields are very satisfactory even for purely aliphatic ketones, since in this case, too, alcohol formation is completely suppressed.t851,t861... 

From the decomposition mechanism and the products formed it can be deduced that DCP primarily generates cumyloxy radicals, which further decompose into highly reactive methyl radicals and acetophenone, having a typical sweet smell. Similarly, tert-butyl cumyl peroxide (TBCP) forms large quantities of acetophenone, as this compound still half-resembles DCP. From the decomposition products of l-(2-6 rt-butylperoxyisopropyl)-3-isopropenyl benzene ( ), it can be deduced that the amount of aromatic alcohol and aromatic ketone are below the detection limit (<0.01 mol/mol decomposed peroxide) furthermore no traces of other decomposition products could be identified. This implies that most likely the initially formed aromatic decomposition products reacted with the substrate by the formation of adducts. In addition, unlike DCP, there is no possibility of TBIB (because of its chemical structure) forming acetophenone. As DTBT contains the same basic tert-butyl peroxide unit as TBIB, it may be anticipated that their primary decomposition products will be similar. This also explains why the decomposition products obtained from the multifunctional peroxides do not provide an unpleasant smell, unlike DCP [37, 38]. 

Cyclohexadienol was prepared by Rickborn in 1970 from reaction of the epoxide of 1,4-cyclohexadiene with methyl lithium.100 A hydrate of naphthalene, 1-hydroxy-1,2-dihydro-naphthalene was prepared by Bamberger in 1895 by allylic bromination of O-acylated tetralol (1-hydroxy-l,2,3,4-tetrahydronaphthalene) followed by reaction with base.101 Hydrates of naphthalene and other polycylic aromatics are also available from oxidative fermentation of dihydroaromatic molecules, which occurs particularly efficiently with a mutant strain (UV4) of Pseudomonas putida.102,103 The hydrates are alcohols and they undergo acid-catalyzed dehydration to form the aromatic molecule by the same mechanism as other alcohols, except that the thermodynamic driving force provided by the aromatic product makes deprotonation of the carbocation (arenonium ion) a fast reaction, so that in contrast to simple alcohols, formation of the carbocation is rate-determining (Scheme 6).104,105... 

Examples of this reaction have long been known, and several have been discussed above (pp. 99-102). Applications of the method to aldehydes of the aromatic series have been reported more recently. Nenitzescu and Gav t 89 observed that equimolal mixtures of benzalde-hyde or anisaldehyde with formaldehyde led to the formation of both possible acids and alcohols, and that if formaldehyde was present in large excess the aromatic- alcohol, and little of the corresponding acid, was formed. The procedure may therefore be looked upon as a method for reducing aromatic aldehydes. Davidson and Bogert90 have worked out experimental conditions for carrying out the reduction of aldehydes by this means to give 85-90% yields of the alcohols. 

The production of hydrocarbons from aromatic alcohols is most readily explained by the hydrogenolysis of the alcohol, but an alternate possibility should be considered. The formation of an aldehyde and its subsequent decarbonylation under reaction conditions could lead to the hydrocarbon. Both toluene and 2-phenylethanol, the mixture of products secured from benzyl alcohol, may be regarded as derived from phenylacetaldehyde as an intermediate ... 

By using sodium borohydride in N,N-dimethylformamide solution containing a molar excess of pyridine as a borane scavenger, direct conversion of both aliphatic and aromatic acid chlorides to the corresponding aldehydes can be achieved in >70% yield with 5-10% alcohol formation. 

Alcohols.—The side chain hydroxyl compounds take the class name of alcohols for they are true aromatic alcohols in formation, reaction and properties. They are neutral not acid, and are formed by methods analogous to those by which the aliphatic alcohols are prepared. They may be looked upon as benzene derivatives of aliphatic alcohols, e.g. CeHs—CH2OH, benzyl alcohol or phenyl methyl alcohol. 

Depending on the catalyst system and the chosen reaction conditions, aliphatic and aromatic alcohols can in general act as substrates for oxidative carbonylations. In principle this reaction type can occur in the presence of metal ions which are able to oxidize CO in the presence of an alcohol function. As already mentioned above, it is also here necessary to carry out the reaction in the presence of a suitable reoxidant in order to establish a catalytic cycle process. Preferably that may be another metal salt, for example CuCU- Typical products and side products which are observed in the oxidative carbonylation of alcohols are alkyl and aryl carbonates, oxalates, formates, haloformates, acetals, and carbon dioxide. 

MTO has also been claimed to be the first transition metal complex to catalyze the direct, solvent-independent formation of ethers from alcohols [30]. Aromatic alcohols give better yields than aliphatic ones and reactions between different alcohols have been used to prepare asymmetric ethers. Also catalyzed by 1 is the dehydration of alcohols to form olefins at room temperature. When primary or secondary amines, respectively, are used as the limiting reagents, direct amination of alcohols gives the expected secondary or tertiary amines in yields of ca. 95 %. Disproportionation of alcohols to carbonyl compounds and alkanes is also observed for aromatic alcohols in the presence of MTO as catalyst. 

Equilibrium is thermodynamically in favor of alcohol formation in the physiological pH range for most aliphatic and aromatic aldehydes i.e., =1.25 X... 

The first three descriptors have been plotted for 27 amines that have similar values in the remaining two dimensions. Carboxylic acids form a tight cluster near, but separate from, the esters. Alcohols are farther away from the acids, and amines are even farther. Aliphatics are widely separated from aromatics. The formation of these clusters is typical and is what justifies calling these dimensions chemical functionality descriptors. ... 

The reagent activates iodobenzene for the allylation of aromatics, alcohols, and acids. AUylstannanes are likewise activated for the allylation of p-benzoquinones, e.g. in the formation of coenzyme Qn using polyprenylalkylstannane. ... 

Partial Oxidation Reactions. Oxidation is used in industry for producing aliphatic and aromatic alcohols, aldehydes, ketones and acids. Generally, oxidation involves splitting of C-C or C-H bonds and formation of C-0 bonds. For example, the partial oxidation of hydrocarbons by molecular oxygen, to form oxygenates that are used as building blocks in the manufacturing of plastics and synthetic fibers, is an important process in the chemical industry. 

Oxidations of organic substrates have also been reported. In the reaction with benzyl alcohol the reactive species is considered to be HMn04, the rate-determining step being the cleavage of the C—H bond of the alcohol. The oxidation of secondary and tertiary aromatic alcohols in acid solution proceeds via the formation of an ester ... 

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