Cyclohexanol, reactions with

Cyclohexanol can be deterrnined colorimetricaHy by reaction with -hydroxy-ben2aldehyde in sulfuric acid (18). This method can be used in the presence of cyclohexanone and cyclohexane. Cyclohexanol and cyclohexanone both show a maximum absorbency at 535 nm but at 625 nm the absorption by cyclohexanone is negligible, whereas cyclohexanol shows appreciable absorption. 

Me3SiCH2CH=CH2i TsOH, CH3CN, 70-80°, 1-2 h, 90-95% yield. This silylating reagent is stable to moisture. Allylsilanes can be used to protect alcohols, phenols, and carboxylic acids there is no reaction with thiophenol except when CF3S03H is used as a catalyst. The method is also applicable to the formation of r-butyldimethylsilyl derivatives the silyl ether of cyclohexanol was prepared in 95% yield from allyl-/-butyldi-methylsilane. Iodine, bromine, trimethylsilyl bromide, and trimethylsilyl iodide have also been used as catalysts. Nafion-H has been shown to be an effective catalyst. 

A few results have been reported on the oxidation of cyclohexanol by acidic permanganate In the absence of added fluoride ions the reaction is first-order in both alcohol and oxidant , the apparent first-order rate coefficient (for excess alcohol) at 25 °C following an acidity dependence k = 3.5-1-16.0 [H30 ]sec fcg/A , depends on acidity (3.2 in dilute acid, 2.4 in 1 M acid) and D2o/ H20 is f-74. Addition of fluoride permitted observation of the reaction for longer periods (before precipitation) and under these conditions methanol is attacked at about the same rates as di-isopropyl ether, although dioxan is oxidised over twenty times more slowly. The lack of specificity and the isotope effect indicates that a hydride-ion abstraction mechanism operates under these conditions. (The reactivity of di-isopropyl ether towards two-equivalent oxidants is illustrated by its reaction with Hg(II).) Similar results were obtained with buffered permanganate. 

The reaction rates cannot be set as high as intrinsically possible by the kinetics, because otherwise heat removal due to the large reaction enthalpies (500-550 kj mol ) will become a major problem [17, 60, 61]. For this reason, the hydrogen supply is restricted, thereby controlling the reaction rate. Otherwise, decomposition of nitrobenzene or of partially hydrogenated intermediates can occur ]60], The reaction involves various elemental reactions with different intermediates which can react with each other ]60], At short reaction times, the intermediates can be identified, while complete conversion is achieved at long reaction times. The product aniline itself can react further to give side products such as cyclohexanol, cyclohexylamine and other species. 

Only one bicyclic peroxide was obtained for each ring system and for 26 and 27 we confirmed that the bromide is cis to the peroxide linkage. In the [2,2.1]-compound this was established from its H n.m.r. spectrum by the absence of long range W-plan coupling for the CHBt proton. The cw-configuration of the [3.2.1] compound was indicated by the lH n.m.r. spectrum of the 2-bromo-3-butoxy-cyclohexanol obtained quantitatively upon reaction with butyllithium (Eq. 24), and has now been confirmed by an X-ray crystal structure determination39). 

The mechanism of chain initiation in cyclohexanol by the reaction with dioxygen was studied by the inhibitor method [57]. It was established that... 

A" 0-Butenolide, 46, 22 /-Butyl alcohol, in synthesis of phenyl /-butyl ether, 45, 89 reaction with sodium cyanate and trifluoroacetic acid, 48, 32 /-Butyl azidoacctatc, 46, 47 hydrogenation of, 45, 47 /-Butyl carbamate, 48,32 /-Butyl chloroacetate, reaction with sodium azide, 45, 47 /ra S-4-/-BuTYI,CYCLOHEXANOL, 47,16... 

Two mechanistic pathways may be considered by which methylcyclopentenes could be produced from cyclohexanol. In the first, (II) and (III) are formed from (I) in parallel reaction with or without consecutive interconversion of the cycloalkenes ... 

The oil contains considerable amounts of derivatives formed by reaction with the solvent cyclohexanol acetate, bicyclohexyl, and a number of high-b>oiling, iodine-containing substances. These by-products are removed only after oxidation. 

A further attempt has been made to develop a predictive model for chirality transfer achieved through alkylation reactions of ester enolates which feature chiral auxiliaries. " Hippurate esters (30) derived from (lI , 25 )-trani-2-(p-substituted phenyl)cyclohexanols were found, on reaction with benzyl bromide, to give (31) with predominantly the S configuration at the alkylation centre but with no correlation between the degree of stereoselectivity (20-98%) and the electron density on the aromatic ring. 

Kinetic studies of hexacyanoferrate(III) oxidations have included the much-studied reaction with iodide and oxidation of the TICI2 anion, of hydrazine and hydrazinium, and of phenylhydrazine and 4-bromophenylhydrazine. These last reactions proceed by outer-sphere mechanisms, and conform to Marcus s theory. Catalyzed [Fe(CN)g] oxidations have included chlororuthenium-catalyzed oxidation of cyclohexanol, ruthenium(III)-catalyzed oxidation of 2-aminoethanol and of 3-aminopropanol, ruthenium(VI)-catalyzed oxidation of lactate, tartrate, and glycolate, and osmium(VIII)-catalyzed oxidation of benzyl alcohol and benzylamine. ... 

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. 

Photolysis of diphenyldiazomethane in MeCN solution in the presence of sufficient 84 yields benzophenone in >90% yield and tetramethyipiperidine in equimolar amounts. A similar photolysis with 4-hydroxy-TEMPO (84, X = OH) gives benzophenone and ether (85) in 16 1 ratio, indicating that attack at the nitroxide center predominated even though it is more hindered than the OH group. In the case of cyclohexanol, which is used as a reference substrate for 4-hydroxy-TEMPO, the reaction with DPC gives >90% yield of the expected ether. ... 

In analogy to 23, the chiralities of [2.2]meta- and [10]paracyclophanecarboxylic acids were also deduced from the results of kinetic resolutions 40-77>. For the application of Horeau s method, (—)-[10]paracyclophanecarboxylic acid (14) was transformed by stereoselective hydrogenation and subsequent sodium borohydride reduction of an intermediate cyclohexanone into the (—)-cis-cyclohexanol 94 which on reaction with racemic 2-phenylbutanoic anhydride afforded a 15% excess of the Ievorotatory acid thereby proving (in agreement with the kinetic resolution of the anhydride of 14, vide supra) the chirality (5) for (—)-14 and all its derivatives 40). Optical comparison with dioxa[10]paracyclophanecarboxylic acid (16) confirmed this result63,108). 

Caprolactam [105-60-2] (2-oxohexamethylenimine, hexahydro-2.fi-azepin-2-one) is one of the most widely used chemical intermediates. However, almost all of the annual production of 3.0 x 106 t is consumed as the monomer for nylon-6 fibers and plastics (see Fibers survey Polyamides, plastics). Cyclohexanone, which is the most common organic precursor of caprolactam, is made from benzene by either phenol hydrogenation or cyclohexane oxidation (see Cyclohexanol AND cyclohexanone). Reaction with ammonia-derived hydroxylamine forms cyclohexanone oxime, which undergoes molecular rearrangement to the seven-membered ring 8-caprolactam. 

Cyclohexanol annelation,8 In the presence of dimethylaluminum chloride, a,/3-unsaturated aldehydes or ketones undergo two consecutive ene reactions with alkylidenecycloalkanes to form bicyclic alcohols. Thus, if the reaction of methylene-cyclohexane and methyl vinyl ketone is conducted at — 20°, the product (I) of the initial ene reaction can be isolated in 39% yield together with traces of 2, which becomes the main product from reactions conducted at 25°. The intermediate is usually not isolable in reactions of a,/l-enals. Thus, reaction of ethylidenecyclopentane and acrolein at 0° gives 3 in 72% yield. An attractive feature of this annelation is that... 

Nitriles.1 Alcohols are converted directly into nitriles by reaction with NaCN and ClSi(CH3)3 and a catalytic amount of Nal. DMF/CH3CN(50/50/v/v) is the most satisfactory solvent. Presumably, ISi(CH3)3 is formed in situ. This reaction is applicable to alcohols of all types it proceeds with inversion in the case of 3/J-cholcstanol but with retention in the case of cyclohexanol. 

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