Cyclohexanol, formation

Photochemical cyclohexanol formation can proceed efficiently (although quantum yields are low, slowing the reaction), and can also show high diastereoselectivity18. In this case, a methyl substituent a to the carbonyl markedly enhances the yield of photocyclization. 

Cyclohexenone, the major product of cyclohexene autoxidation was reduced to cyclohexanol and cyclohexenol in a ratio of 1 1.4 under the oxidation condition without oxygen, while cyclohexenol was not reduced appreciably. Thus, the reduction of cyclohexenone during the oxidation can account for only a part of the cyclohexanol formation in the TPPMn-NaBH4-02 reaction, and a much more important source of cyclohexanol seems to be cyclohexene oxide this is leased on the following observations (see Figure 11) ... 

Figure 11. Cyclohexanol formation during cyclohexene oxidation...

Competition studies between the alkenyl and the aldehyde groups as radical acceptors for the alkyl radical have been investigated in detail. It is known that cyclohexanol formation usually overwhelms... 

A/K = cyclohexanol to cyclohexanone ratio. Kinetic isotope effect of cyclohexanol formation. Efficiency based on H2O2. 

Cyclohexanol. See Cyclohexanol Cyclohexanol acetate. See Cyclohexyl acetate Cyclohexanol, 4-t-butyl- Cyclohexanol, 4-(1,1-dimethylethyl)-. See 4-t-Butylcyclohexanol Cyclohexanol, 2-(1,1-dimethylethyl)-, acetate. See 2-t-Butylcyclohexyl acetate Cyclohexanol formate. See Cyclohexyl formate Cyclohexanol, 1 -((1-hydroperoxycyclohexyl) dioxy)-. See Cyclohexanone peroxide Cyclohexanol, 4,4 -isopropylidenedi-. See Bisphenol A, hydrogenated Cyclohexanol, 2-isopropyl-5-methyl-. See Menthol... 

In Problem 5 17 (Section 5 13) we saw that acid catalyzed dehydration of 2 2 dimethyl cyclohexanol afforded 1 2 dimethylcyclohexene To explain this product we must wnte a mecha nism for the reaction in which a methyl shift transforms a secondary carbocation to a tertiary one Another product of the dehydration of 2 2 dimethylcyclohexanol is isopropyhdenecyclopentane Wnte a mechanism to rationalize its formation... 

Cycloahphatics capable of tertiary carbocation formation are candidates for nucleophilic addition of nitriles. HCN in strong sulfuric acid transforms 1-methyl-1-cyclohexanol to 1-methyl-1-cyclohexylamine through the formamide (47). The terpenes pinene (14) [2437-95-8] and limonene [5989-27-5] (15) each undergo a double addition of HCN to provide, after hydrolysis, the cycloahphatic diamine 1,8-menthanediamine (16) (48). 

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. 

The alkene mixture obtained on dehydration of 2,2-dimethyl-cyclohexanol contains appreciable amounts of 1,2-dimethylcyclohexene. Give a mechanistic explanation for the formation of this product. 

This hypothesis would agree also with the results of the study of the influence of added substances on some other reactions (124). As an example, dehydration of cyclohexanol on alumina at 220°C is retarded by cyclohexanone, the dehydrogenation of cyclohexanol to cyclohexanone (the second reaction branch) not occurring with this catalyst at all. Hence, cyclohexanone is adsorbed on dehydration centers, on which the reaction which would lead to its formation does not take place at all. A similar result was obtained also for the second reaction branch, the dehydrogena-... 

The formation of ethers such as 1806 by EtsSiH 84b can also be catalyzed by trityl perchlorate to convert, e.g., benzaldehyde in 84% yield into dibenzyl ether 1817 [48]. The combination of methyl phenethyl ketone 1813 with O-silylated 3-phenyl-n-pro-panol 1818, in the presence of trityl perchlorate, leads to the mixed ether 1819 in 68% yield [48] (Scheme 12.15). Instead of trityl perchlorate, the combination of trityl chloride with MesSiH 84a or EtsSiH 84b and sodium tetrakis[3,5-bis-(trifluoro-methyl)phenyl]borane as catalyst reduces carbonyl groups to ethers or olefins [49]. Employing TMSOTf 20 as catalyst gives very high yields of ethers. Thus benzaldehyde reacts with O-silylated allyl alcohol or O-silylated cyclohexanol to give the... 

This type of fission has been observed in a detailed examination of the oxidation of tertiary alcohols by Co(ril). The kinetics are similar to those reported for cyclohexanol vide supra) although the rate is about 40 times less. The possibility of alkoxyl radical formation seems attractive, for Co(III) is known to oxidise... 

In a similar way, numerous P-chloroalkylphosphonic acids undergo fast and quantitative hydrolysis at pH > 5 94). A typical example is the fragmentation of 2-chloro-decyl-l-phosphonic acid in the presence of cyclohexylamine with formation of 1-decene (in contrast, other bases such as pyridine, triethylamine, and dimethylaniline effect only HC1 elimination to form 1-decene-l-phosphonic acid). Added alcohols, such as ethanol, allyl alcohol, cyclohexanol, tert-butanol, and phenol are phosphorylat-ed. 

A final source of evidence for the formation of inclusion complexes in solution has been derived from kinetic measurements. Rate accelerations imposed by the cycloamyloses are competitively inhibited by the addition of small amounts of inert reagents such as cyclohexanol (VanEtten et al., 1967a). Competitive inhibition, a phenomenon frequently observed in enzymatic catalyses, requires a discrete site for which the substrate and the inhibitor can compete. The only discrete site associated with the cycloamyloses is their cavity. 

Aluminum chloride, used either as a stoichiometric reagent or as a catalyst with gaseous hydrogen chloride, may be used to promote silane reductions of secondary alkyl alcohols that otherwise resist reduction by the action of weaker acids.136 For example, cyclohexanol is not reduced by organosilicon hydrides in the presence of trifluoroacetic acid in dichloromethane, presumably because of the relative instability and difficult formation of the secondary cyclohexyl carbocation. By contrast, treatment of cyclohexanol with an excess of hydrogen chloride gas in the presence of a three-to-four-fold excess of triethylsilane and 1.5 equivalents of aluminum chloride in anhydrous dichloromethane produces 70% of cyclohexane and 7% of methylcyclopentane after a reaction time of 3.5 hours at... 

Under certain conditions, the trifluoroacetic acid catalyzed reduction of ketones can result in reductive esterification to form the trifluoroacetate of the alcohol. These reactions are usually accompanied by the formation of side products, which can include the alcohol, alkenes resulting from dehydration, ethers, and methylene compounds from over-reduction.68,70,207,208,313,386 These mixtures may be converted into alcohol products if hydrolysis is employed as part of the reaction workup. An example is the reduction of cyclohexanone to cyclohexanol in 74% yield when treated with a two-fold excess of both trifluoroacetic acid and triethylsilane for 24 hours at 55° and followed by hydrolytic workup (Eq. 205).203... 

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]. 

The formation of radicals from hydrogen peroxide in cyclohexanol was measured by the free radical acceptor method [60] the effective rate constant of initiation was found to be equal to ki = 9.0 x 106 exp(—90.3/RT) s 1. For the first-order decomposition of H2O2 in an alcohol medium, the following reactions were discussed. 

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