Cyclohexanediol, conversion

Cyclohexaamylose-N-methylacetohydroxamic acid, preparation of, 23 254 Cyclohexadienes, 20 293 reaction with HCN, 33 19, 20 on silica, reactions of, 34 54-56-34 64 cracking, 34 55, 72 vibrational spectra, 42 243 Cyclohexadienyl radicals, ESR of, 22 300 1,4-Cyclohexanediols, conversion of ethers, mechanism, 35 361-364 Cyclohexanes, 33 101, 102, 103 autoxidauon of, 25 303 conformational analysis of, 18 9-17 dehydrogenation, 31 14, 21-22 benzene accumulation over platinum, 36 18... 

Reaction of trans-1,2-cyclohexanediol with para-formaldehyde in the presence of Indion 130 as catalyst to yield the corresponding cyclic formal has been successfully carried out (Matkar and Sharma, 1995). A conversion of 52% was realized with 70% selectivity towards cyclohexanediol formal the other side products are rrans-hexahydrobenzo-l,3,5-trioxypin, di(tra i -2-hydroxycyclo-hexyloxy) methane. 

The oxidation of cyclohexanol to cyclohexanone with fluorine and aqueous acetonitrile was performed in a single-channel microreactor operated under annular flow at room temperature. A conversion of 84% and a selectivity of 74% were observed [313], In a similar way, diols such as 1,2-cyclohexanediol were partly or fully oxidized. A 53% selectivity to the monooxidation product was obtained at a conversion of 87% the dioxidation product was obtained with 30% yield. 

The oxidation of vic-diols is often accompanied by cleavage of the C-C bond to yield ketones and/or aldehydes. Especially the clean conversion of (cyclohexene to) 1,2-cyclohexanediol to adipic acid (Fig. 4.76) has received tremendous interest [229]. 

Draw a stepwise mechanism for the conversion of dihalide A and 1,4-cyclohexanediol to polyether B in the presence of AICI3. 

ROM—>RBr. In the cyclohexane series reaction of diols with PBr is attended with rearrangements. Thus treatment of the 1,3- and 1,4-cyclohexanediols with PBrj affords mixtures of cis- and trans-1,3- and l,4-dibromides. Eliel and Haber found that cu-d-i-butylcyclohexanol reacts with PBr to give trani-4-/-butylcyclo-hexyl bromide, together with a small amount of olefin and a mixture of dibromides. Thus PBr, is evidently superior to PBr, for conversion of secondary alcohols into bromides. However, the Hunsdiecker reaction seems to be the method of choice for preparation of cyclohexyl bromides. ... 

Gravel and Bordeleau have demonstrated that the cyclohexanediol (219) can be converted into the deoxysugar (220) by irradiation in the presence of benzophenone, acetonitrile and thiophenol. The conversion of (219) into (220) involves the formation of the aldehyde (221) that is converted into the acetal, i.e. the deoxysugar. An extension of this work has demonstrated that deoxyazasugars can also be formed using the same conditions. Thus irradiation of (222) gave the aldehyde (223) which can then be cyclized by the same path used for the formation of (220). The conditions used were irradiation at 350 nm in acetonitrile solution with xanthene and thiophenol. 

Titanium framework-substituted aluminophosphate, TAPO-5, gave a 30.3% selectivity to AA at total cyclohexene conversion, in 72 h reaction time at 80 °C [35c]. However, when the filtered TAPO-5 catalyst was reused its activity was significantly diminished. The major by-product was 1,2-cyclohexanediol, which is formed as reaction intermediate. The trans isomer was more slowly transformed into 2-hydroxycyclohexanone than the cis isomer. A detailed investigation of the mechanism indeed showed that the trans-diol formed by ring opening of the cyclohexene epoxide, whereas the cis isomer formed via a free-radical mechanism. Scheme 7.14 shows the mechanism proposed. 

There are few reports of successful one-step synthesis of primary diamines, and the examples are limited to amines with a special structure. Amination of 1,4-cy-clohexanediol in supercritical ammonia (135 bar) over a Co-Fe catalyst alforded 67 % 1,4-diaminocyclohexane [21]. Excess ammonia, as both supercritical solvent and reactant, and short contact time in the continuous fixed-bed reactor favored the desired reactions. In the best example the cumulative selectivity for the diamine and the intermediate amino alcohol was 97 % at 76 % conversion. Recycling of the unreacted diol and amino alcohol can provide an alternative to the eurrent process, the hydrogenation of pnra-phenylenediamine. The high seleetivity was because of the rigid structure and the relative positions of OH functionality in the substrate. For comparison, amination of 1,4-butanediol under similar conditions yielded pyiTolidine as the major product 1,4-diaminobutane was barely detectable. When 1,3-cyclohexanediol was aminated with the same catalyst in the continuous system, the yield of 1,3-diaminoeyclohexane dropped below 5%, mainly because elimination of water led to undesired monofunctional products via a,/9-unsaturated alcohol, ketone, and/or amine intermediates [22]. 

Silver oxide can also oxidize primary alcohols directly to the acid, as in the oxidation of 1-dodecanol to dodecanoic acid. Oxidation of 1,2-diols is accompanied by cleavage to the diacid (sec. 3.7.C), as in the conversion of 1,2-cyclohexanediol to adipic acid in 89% yield. ... 

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