Cycloalkanes from alcohols

Cycloalkanes can be synthesized from alcohols containing double-bond systems. 

ILs based on the l-alkyl-3-methyIimidazoIium cation, [C CiIm] , or tetra-alkylammonium cation, [(C )4N]l are among the most popular and commonly studied or used in technological improvements. As for the anions, l7is(trifluoromethylsulfonyl)imide, [Tf2N], and alkylsulfate, [C S04] (n = 1, ll 8), are much superior compared to the more commonly investigated hexafluorophosphate, [PFg] , and tetrafluoroborate, [BF4], being hydrolytically stable and less viscous. Comparing the results of the solubility of ILs in typical solvents from different publications, it can be concluded that the miscibility gap in the liquid phase increases in the order alcohol < aromatic hydrocarbon < cycloalkane < n-alkane [50-54,66,78,79,95-100,127-136]. 

Cycloalkanes can be oxygenated when irradiated in the presence of nitrobenzene.196 A 50% yield of cyclohexanol and cyclohexanone is achieved from cyclohexane. Since the product ratio is independent of reaction time, the alcohol is not an intermediate in ketone formation. Isomeric 1,2-dimethylcyclohexanes give an identical mixture of the isomeric tertiary alcohols, indicative of conformational equilibration and the presence of a radical intermediate. 

WATER-AIR EQUILIBRATION. McAuliffe (6) introduced a multiple phase equilibrium procedure for the qualitative separation of hydrocarbons from water-soluble organic compounds. For n-alkanes, more than 99% were found to partition in the gas phase after two equilibrations with equal volumes of gas and aqueous solution. Cycloalkanes require three equilibrations to be essentially completely removed, and oxygen-containing organic compounds (e.g., alcohols, aldehydes, ketones, and acids) remain in the aqueous layer. Thus, after equilibration with equal volumes of gas, an immediate clue is given regarding the identification of the compound. More details of this technique can be found in Chapter 7. 

Figure 6.5. Homologous series plots (a) linear (b) logarithmic. 1 = alkanes, 2 = cycloalkanes, 3 = esters, 4 = aldehydes, 5 = ketones, 6 = alcohols. Reprinted with permission from J. S. Lewis, H. W. Patton, and W. I. Kaye, Anal. Chem. 1956, 28, 1370. Copyright 1956, American Chemical Society.

Reductive dehalogenation is an efficient method of synthesis of cyclopropanes spiroannulated to five- and higher-membered carbocycles (i.e. compounds in which spiroannulation does not result in accumulation of extra strain) . The required gem-(dihalomethyl)cycloalkanes are usually prepared by halogenation of the precursor diols (equation 1). The cyclization is most efficiently accomplished in the Zn-alcohol-water system . For example, spiro[2.5]octane 7 was prepared in 91% yield using this procedure. This method is useful even for a one-step preparation of bis-spirocyclopropyl compounds as exemplified in equation 2. However, the application of the reductive dehalogenation method to the synthesis of more strained SPC (i.e. spirohexane or spiropentane) often leads to rearranged products. For example, methylenecyclopentane was the only product obtained from bis(bromomethyl)cyclobutane (equation 3) ... 

Phenothiazine radicals have been generated in various radiolytic experiments. Pulse radiolysis of phenothiazine in aerated cycloalkane solutions gives rise to phenothiazinyl (251). ° The mode of oxidation is believed to involve abstraction of H from the heterocycle by cycloalkylperoxyl radicals. Under similar conditions, 10-methylphenothiazine gives 261. Pulse radiolysis of phenothiazine in acetonitrile has also been documented. The reduction of phenothiazine dyes under radiolytic conditions has been reported. Several years ago, Ayscough and Thomson obtained paramagnetic products from X-irradiation of acid alcoholic solutions of Methylene Blue and other thiazine dyes. Low-resolution ESR spectra of the corresponding cation-radicals were recorded. 

Hermann 38) has estimated the coefficient b0 values for a series of alkanes and cycloalkanes and for a number of alkylbenzenes. The b0 values are 33 A-2 for alkanes and cycloalkanes and 30 A-2 for aromatic systems38 . From the data obtained by Amidon et al.42) it appears that the b0 value for monofunctional aliphatic alcohols, ethers, aldehydes, ketones, and fatty acids is constant and amounts to 22.6 A-2. A similar b0 value of 22.0 A-2 has been found by Chotia 47> for the side chains of nonpolar amino acids — those of alanine, valine, leucine and phenylalanine. For the side chains of serine, threonine, histidine, methionine, and ffor no apparent reason) tryptophan, the coefficient b0 value is ca. 13-15 A-2 47>. 

The different alkanes and cycloalkanes used were octane, isooctane, hexane and cyclohexane. 1° ROH was n-propyl alcohol, 3° ROH was tert-hutyl alcohol. All (>2 values are from Reference 186. 

Some oil products are biologically quite easily metabolized, such as alkanes, alkenes, cycloalkanes and aromates. Products of this activity are differently oxidized oxygen derivatives (peroxides, alcohols, phenols, aldehydes, acids, etc.). In this way microorganisms enable self-cleaning processes in soil and rivers. The rate of these degradation reactions depends on sufficient access of oxygen from the air. 

An oxidizing reagent based on potassium ferrate(Vl) has been described [78], This potassium ferrate, when used in conjunction with an appropriate heterogeneous catalyst such as KIO montmorillonite clay, is a strong oxidant which produces cycloalkanols and cycloaUcanones from cycloalkanes, and benzyl alcohol and benzaldehyde from toluene. 

From To - Alkanes Cycloalkanes Alkenes Alkynes Aryls Halogen compounds Alcohols Phenols Ethers, Quinones B. and Si compounds P and 6i compounds Nitro, Nitroso, Azo, Azoxy, Hydrazo, ides Amines Organometallic Aldehydes Ketones Acids, Anhydrides, Esters Arn.des, Amidines, Nitriles Hydroky-aldehydes Amino Heterocycles Nucleosides Miscellaneous, including heterocycles... 

Other saccharides (sugar alcohols) also include cycHtols (alicyclic polyols), because they have similar properties, although they are not derived from sugars by simple reduction. CycHtols are cycloalkanes, in which at least three ring carbon atoms are substituted (each of them only once) by hydroxyl or alkoxyl groups. 

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