Pulse radiolysis study of the initial steps of the polymerization of cyclohexyl acrylate and cyclohexyl methacrylate

Pulse radiolysis with kinetic spectroscopic detection was applied to study the kinetics of the first steps of radiation induced polymerization of cyclohexyl acrylate and cyclohexyl methacrylate in cyclohexane solvent. The reactions were initiated by cyclohexyl radicals produced in the radiolysis of the solvent. The transient absorption spectra of the -carboxyalkyl type radicals produced in addition reaction show maxima around 300 nm. This shifts to longer wavelength with time after the pulse. This phenomenon was explained by the oligomerization reaction. From the kinetic curves average rate coefficients of termination for the oligomer radicals (2k_t) were determined as a function of time elapsed after the electron pulse. The values obtained were compared with those calculated for other (acrylate and methacrylate type) monomers.     

Gas phase thermolysis of cyclohexyl thiol

The pyrolysis of cyclohexyl thiol has been studied in a static system at subambient pressures in the temperature range 420–497°C. It is proposed that in the presence of a large excess of cyclohexene the mechanism is a radical non-chain process.

---

, , 420–497°C. , .

     

Synthesis of tricyclic cyclohexyl aryl ethers

Conclusions The cyclic ethers, m- and p-(phenoxyphenoxy) cyclohexanes, were synthesized by the Ullmann reaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1405–1406, June, 1972.     

肉桂酸环己酯的合成研究

肉桂酸环己酯为具有令人愉快的果香香气的无色粘稠液体 ,不溶于水 ,易溶于乙醇 ,常用于食用香精和日化香精的配料中 ,是典型的香料和食品添加剂[1,2 ] 。据报道 ,目前合成肉桂酸环己酯的方法有二 ,一是传统的硫酸催化酯化法 ,二是用路易斯酸ＦｅＣｌ3·6Ｈ2 Ｏ做催化剂来合成肉桂酸环己酯 ,两种方法虽有各自的优点 ,但它们的收率均不高 ,分别为 78.4%、73 .4% [3] 。近年来人们用相转移催化技术合成了许多酯类[4 ,5] ,受其启发 ,我们在催化剂浓硫酸中加入聚乙二醇 40 0作为混合催化剂来合成肉桂酸环己酯 ,获得了满意的结果 ,反应收率达 84.8…     

Cyclosilethynes containing exocyclic cyclopentyl and cyclohexyl groups

The reaction of BrMgCCSiMe₂CCSiMe₂CCSiMe₂CCSiMe₂CCMgBr with chloro(cyclopentyl)(methyl)silane in a large excess of THF gave 1-cyclopentyl-1,4,4,7,7,10,10,13,13-nonamethyl-1,4,7,10, 13-pentasilacyclopentadeca-2,5,8,11,14-pentayne. Similarly, 1,10-di(cyclopentyl)- or 1,6-di(cyclopentylmethyl)-1,4,4,7,7,10,13,13,16,16-decamethyl-1,4,7,10,13,16-hexasilacyclooctadeca-2,5,8,11,14,17-hexaynes were synthesized from BrMgCCSiMe₂CCSiMe₂CCMgBr and dichloro(cyclopentyl)methylsilane or dichloro(cyclopentylmethyl)(methyl)silane. Condensation of Me₂Si(CCMgBr)₂ with dichloro(cyclohexyl)-methylsilane afforded 1,7-di(cyclohexyl)-1,4,4,7,10,10-hexamethyl-1,4,7,10-tetrasilacyclododeca-2,5,8,11-tetrayne.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1282–1284.Original Russian Text Copyright © 2004 by O. Yarosh, Zhilitskaya, N. Yarosh, Albanov, Klyba, Voronkov.This revised version was published online in April 2005 with a corrected cover date.     

Electron impact fragmentation of some cyclohexyl thiophosphororganic amides

This paper presents the mass spectra, fragmentation pathways and structures of ions obtained by electron impact from methyl cyclohexyl phosphinomorpholinylamidothioate (1), cyclohexyl phosphonomorpholinylamidochloridothioate (2), cyclohexyl morpholinylamidophosphonothioic acid (3) and O-methyl cyclohexyl phosphonomorpholinylamidothioate (4). The fragmentation pathways and ion structures were established by exact mass determinations on compound 1 and by metastable transitions of all the compounds.     

Kinetics of the self reaction of cyclohexyl radicals

The kinetics of the self-reaction of cyclohexyl radicals was studied by laser photolysis/photoionization mass spectroscopy. Overall rate constants were obtained in direct real-time experiments in the temperature region 303-520 K and at bath gas (helium with up to 5% of radical precursors) densities (3.00-12.0) × 10(16) molecules cm(-3). Cyclohexyl radicals were produced by a combination of the 193 nm photolysis of oxalyl chloride ((CClO)(2)) with the subsequent fast reaction of Cl atoms with cyclohexane, and their initial concentrations were determined from real-time profiles of HCl. The observed overall c-C(6)H(11) + c-C(6)H(11) rate constants demonstrate negative temperature dependence, which can be described by the following expressions: k(1) = 4.8 × 10(-12) exp(+542 K/T) cm(3) molecule(-1) s(-1), with estimated uncertainty of 16% over the 303-520 K temperature range. The fraction of disproportionation equal to 41 ± 7% was determined at 305 K; analysis of earlier experimental determinations of the disproportionation-to-recombination branching ratio leads to recommending this room-temperature value for other temperatures. The corresponding temperature dependences of the recombination (1a, bicyclohexyl product) and the disproportionation (1b, cyclohexene and cyclohexane products) channels are k(1a) = 2.8 × 10(-12) exp(+542 K/T) and k(1b) = 2.0 × 10(-12) exp(+542 K/T) cm(3) molecule(-1) s(-1), with estimated uncertainties of 20% and 29%, respectively.     

The properties of phenyl cyclohexyl ferroelectric liquid crystals

To continue the search for novel series of ferroelectric liquid crystals, an additional two series of compounds, C S(+)-4-[(2-methylbutyl)phenyl]4'-trans-n-alkylcyclohexyl) benzoates and D S(+)-4-[(4-methylhexanoyl)phenyl]4'(4'-trans-n-alkylcyclohexyl) benzoates, where alkyl = C₅-C₆ are reported in this paper. Their mesomorphic properties have been characterized by optical textural observations and DSC. Some of these compounds show a C-S*_C-S_A-N*-I phase transition sequence. The effects of the alkyl chains on transition temperatures and optically active terminal groups on phase behaviour are discussed.     

The reaction of cyclohexyl radicals with carbon tetrachloride

The photolysis of azocyclohexane, carbon tetrachloride, and cyclohexane at 360 nm has been investigated over a wide temperature range. At moderate temperatures a chain reaction ensues from which the following approximate rate constants could be determined assuming 2CCl₃. → C₂Cl₆, k₅ = 10^9.7 (303–673K): The really striking feature of the results is that they show that termination in bicyclohexyl [reaction (7)] is extremely slow: The root-mean-square rule for estimating the cross-combination rate is also followed. The photolysis of carbon tetrachloride and cyclohexane at 250 nm has also been investigated. The reaction is complicated by the occurrence of two concurrent photolytic processes, the main one yielding trichloromethyl radicals and chlorine atoms, and the subsidiary one yielding dichlorocarbene and molecular chlorine. Nonetheless the results from this reaction can be interpreted in the medium temperature range 360–430K, where long chains are present, in terms of the rate constants derived from the azocyclohexane system.     

Diastereoselective palladium-catalyzed alpha-arylation of 4-substituted cyclohexyl esters

A diastereoselective palladium-catalyzed arylation of 4-substituted cyclohexyl esters has been developed. The reaction proceeds at room temperature in the presence of [(t-Bu3P)PdBr]2 providing products in up to 37:1 dr.     

Inverse gas chromatography of poly(cyclohexyl methacrylate)

Inverse gas chromatography is applied to determine the glass transition temperature T_g of poly-(cyclohexyl methacrylate). Both good and bad solvents for the polymer are used as molecular probes. Although the transition is clearly detected by both types of probes, only the nonsolvents yield a T_g in quantitative agreement with the value determined by differential scanning calorimetry. The relative depth of penetration of the probe in the polymer phase is calculated from retention volume data. Also, the height equivalent to a theoretical plate is calculated from peak halfwidths. Both calculated magnitudes show a temperature dependence which significantly differs from good to bad solvents. Some kind of diffusion-limited penetration of the probe in the bulk of the glassy polymer may be responsible for the difference.     

Free-radical generation mechanism and antimalarial activity of cyclohexyl endoperoxides

A kinetic analysis has been carried out for a cascade of intramolecular oxidation reactions of free radicals generated in the redox reactions of substituted cyclohexyl endoperoxides (15 compounds) with the Fe²⁺ ion. Each radical conversion reaction has been characterized by its enthalpy, activation energy, and rate constant. Kinetic characteristics have been calculated by the intersecting parabolas method. Depending on their structure, cyclohexyl endoperoxides generate one to three radicals. There is a linear empirical correlation between the number of radicals generated by a peroxide and its molar antimalarial activity (IC ₅₀/M, where M is the molar mass of the peroxide). The peroxides that generate no more than one radical show no antimalarial activity.     

Kinetics of the reaction between cyclohexylsulfonyl and cyclohexyl radicals

Previous pulse photolysis studies on the combination of cyclohexylsulfonyl radicals /1/ have been extended to determination of the rate constant for the reaction ₆H₁₁SO₂+₆H₁₁prod. in a solution of cyclohexane at 293–323 K.

---

/1/ . C₆H₁₁SO₂+C₆H₁₁ 293–323 .

     

Adsorption change of cyclohexyl acetylene on gold nanoparticle surfaces

The conformational changes of cyclohexyl acetylene (CHAL) on gold nanoparticle surfaces were investigated by means of concentration- and temperature-dependent surface-enhanced Raman scattering (SERS). Depending on concentrations and temperatures, the spectral changes of the acetylene ν(C≡C) stretching vibration on gold nanoparticles appeared to be more conspicuous than those of cyclohexyl ring modes. The density functional theory (DFT) calculation was performed at the level of B3LYP/6-31G++(d,p) to compare the energetic stability and vibrational frequencies of the various conformers of cyclohexanethiol (CHT) and CHAL. The DFT calculations were also carried out at the level of B3LYP/LACVP** on the CHAL molecule adsorbed on Au clusters at several sites to explain the spectral changes of the acetylene ν(C≡C) stretching vibration.     

Thermodynamic properties of some cyclohexyl esters in the condensed state

The heat capacities and the enthalpies of phase transitions of cyclohexyl esters (formate, acetate, butyrate, and valerate) in the condensed state between T =  (5 and 320) K were measured in a vacuum adiabatic calorimeter. It was found that all liquid compounds were supercooled by cooling them fromT =  300 K at a rate of (0.02 to 0.03)K · s ^− 1and formed glasses. Crystalline phases were obtained for all esters and the residual entropies of glasses at T →  0 were evaluated. The glass transition temperatures and the heat capacity jumps accompanying the glass transitions, as well as the thermodynamic parameters of fusion of crystalline phases, were determined for all the esters. The molar thermodynamic functions of the investigated compounds in the crystalline, liquid, supercooled liquid, and glassy states were obtained. The regular changes of some thermodynamic properties in the series of cyclohexyl esters are discussed.