22499-63-4

Upstream product

• 110-83-8 cyclohexene 
• 108-93-0 cyclohexanol 
• 110-82-7 cyclohexane 
• 82166-21-0 methyl cyclohexane 
• 100-47-0 benzonitrile 

Downstream Products

• 1462-03-9 1-methylcyclopentanol 
• 108-94-1 cyclohexanone 
• 108-93-0 cyclohexanol 

Relevant academic research and scientific papers

Chemical ionization using CF3+: Efficient detection of small alkanes and fluorocarbons

The trifluoromethyl ion CF3+ is evaluated as a chemical ionization (CI) precursor in a compact Fourier Transform Ion Cyclotron Resonance (FTICR) mass spectrometer. It reacts with alkanes by hydride abstraction allowing characterization and quantification of alkanes up to C4 and cyclic. With larger alkanes fragmentation occurs. Fluorocarbons react by fluoride abstraction. Rate coefficients have been measured for reaction with alkanes, fluoroalkanes, chlorofluoroalkanes as well as several common VOCs. Use of CF3+ for trace analysis in air has been tested on an air sample containing traces of acetone, toluene, benzene and cyclohexane. The results are consistent with those obtained with H3O+ precursor and allow additional cyclohexane quantification.

Protonation of trimethylsilyl-substituted carbon-carbon multiple bonds in aliphatic systems. Conformational dependence of the β-silyl stabilizaton of carbocations

Rates of carbon protonation to give carbocation products were measured in concentrated perchloric acid solutions for cyclohexene, propyne, 1-hexyne, and their 1-trimethylsilyl-substituted analogs. The trimethylsilyl substituent accelerated the reaction markedly and provided the following β-silyl carbocation stabilizing effects: δΔG? = 5.7 kcal/mol-1 for the cyclohexyl system and δΔG? = 6.5 kcal mol-1 for both acetylenic systems. These effects are substantially greater than δΔG? = 2.9 and 3.4 kcal mol-1 found previously for the protonation of ethyl vinyl ether and phenylacetylene, which suggests that the silyl effects in these previous systems were attenuated by additional carbocation stabilization provided through their ethoxy and phenyl groups. The present effects, on the other hand, fall far short of δΔG? = 16-17 kcal mol-1 found for conformationally optimum systems. The influence of conformation on the magnitude of β-silyl effects and how this impinges on the presently studied systems is discussed.

Dissociative proton transfer reactions of H3+, N2H+, and H3O+ with acyclic, cyclic, and aromatic hydrocarbons and nitrogen compounds, and astrochemical implications

A flowing afterglow-selected ion flow drift tube has been used to measure the rate coefficients and product ion distributions for reactions of H3O+, N2H+, and H3+ with a series of 16 alkanes, alkenes, alkynes, and aromatic hydrocarbons as well as acrylonitrile, pyrrole, and pyridine. Exothermic proton transfer generally occurs close to the collision rate. The reactions of H3O+ are mostly nondissociative and those of H3+ are mostly dissociative, but many reactions, especially those of N2H+, have both dissociative and nondissociative channels. The dissociative channels result mostly in H2 and/or CH4 loss in the small hydrocarbons and in toluene, loss of C2H2 from acrylonitrile, and loss of HCN from pyrrole. Only nondissociative proton transfer is observed with benzene, pyridine, and larger aromatics. Drift tube studies of N2H+ reactions with propene and propyne showed that increased energy in the reactant ion enhances fragmentation. Some D3+ reactions were also investigated and the results suggest that reactions of H3+ with unsaturated hydrocarbons B proceed through proton transfer that forms excited (BH+)* intermediates. Pressure effects suggest that a fraction of the (BH+)* intermediates decomposes too rapidly to allow collisional stabilization in the flow tube (t -8 s). The other low-energy (BH+)* intermediates are formed by the removal of up to 40% of the reaction exothermicity as translational energy, and these intermediates result in stable BH+ products. The results suggest that, in hydrogen-dominated planetary and interstellar environments, the reactions of H3+ can convert C2-C6 hydrocarbons to smaller and less saturated molecules, but polycyclic aromatics are stable against decomposition by this mechanism. The dissociative reactions of H3+ can therefore favor the accumulation of small unsaturated hydrocarbons and aromatics in astrochemical environments.

Reactions of Hydrated Hydronium Ions and Hydrated Hydroxide Ions with Some Hydrocarbons and Oxygen-Bearing Organic Molecules

The rate coefficients and ion products have been determined at 300 K for the reactions of H3O(1+)*(H2O)0,1,2,3 positive ions and OH(1-)*(H2O)0,1,2 negative ions with six hydrocarbons and six oxygen-containing organic species using a selected ion flow tube (SIFT) for the positive ions and a flowing afterglow (FA) for the negative ions.This study was initiated in support of a major development program of the SIFT and FA as chemical ionization devices for the analysis of trace gases in air and especially of human breath and the vapors emitted by fruits and food products.The H3O(1+) and OH(1-) ions mostly react with the molecules, MH, via proton transfer, producing respectively MH2(1+) and M(1-) ions, which is ideal for gas analysis.The hydrated hydronium ions and the hydrated hydroxide ions are largely unreactive with the hydrocarbons included in this study, but they are very reactive with the oxygen-containing organic molecules undergoing ligand switching reactions producing mostly MH2(1+) and M(1-) hydrates.The details of the reactions (e.g. the number of H2O molecules either ejected from the intermediate complexes or remaining associated with the MH2(1+) and MH(1-) "core ions") are controlled largely by the reaction energy as far as this can be determined.The utility of the reactions of these hydrated ions as chemical ionization agents in atmospheric trace gas analysis is alluded to.Additionally, new FA data on the three-body association reactions of OH(1-) and OH(1-)*H2O with CO2 are presented.

Elemental Compositions from Daughter Ion Spectra of m1+ and 1 + 1>+: Some Applications of the Method

The elemental compositions of ions can be determined in tandem mass spectrometry by comparing the daughter ion spectra of the m1+ and 1 + 1>+ ions.The method is demonstrated for mass-analyzed ion kinetic energy spectra but is applicable to all types of daughter ion spectra, including complex collisionally activated dissociation spectra.In this work, the method is applied to compounds that produce daughter ions of known elemental compositions, and the errors and limitations are evaluated.Following that test, the procedure is applied to a compound that may produce daughters of more than one possible elemental composition.The method is sometimes useful even if the formula of the parent is not known; that is, the formulae of unknown parent and daughter ions may be found.Locating a specific atom in an isotopically labeled molecule is another capability of the method.The basic equation of the method was generalized and incorporated into a computer program for performing the calculations.

Does the Cyclohehyl Cation Exist in the Dilute Gas State? Direct Evidence from a Radiolytic Study

The isomeric composition of the daseous C6H11+ cations obtained via hydride ion abstraction from c-C6H12 has been investigated by allowing the charged species to react in the gas phase with water and analyzing the neutral products formed.The nature and the yields of the major products, cyclohexanol, cyclohexanone, and 1-methylcyclopentanol, and their dependence on the pressure and the composition of the gaseous system provide direct evidence for the existence of the cyclohexyl cation in the dilute gas state, with a lifetime in excess of 10-7 s, and confirm its facile rearrangement to the more stable 1-methylcyclopentyl ion.

Isomerization of Gas-Phase Hydrocarbon Ions. Radical Trapping. 3

Carbon-centered radicals, produced in a chemical-ionization plasma by ion-electron recombination, are trapped in a fast gas-phase reaction with tetracyanoquinodimethan and the products of this reaction, after ionization by electron capture, are analyzed, uzing mass selected collisional activation mass spectrometry.The structures of the ions at the instant of neutralization, 10-5-10-4 s after formation, are determined from the collisional activation results.Isomerization occurring in selected nH2n-1>+, nH2n+1>+, and nHn+(n-7)>+ ions, n9, have been delineated and the results compared to previously published gas-phase and/or solution results.

Proton-Transfer Reactions Involving Alkyl Ions and Alkenes. Rate Constants, Isomerization Processes, and the Derivation of Thermochemical Data

Rate constants and mechanisms have been determined for proton-transfer reactions of type AH+ + M ->/+ + A, where A is propylene, isobutene, cyclopentene, and cyclohexene.In order to avoid competing side effects the AH+ reactant ions are generated in alkanes and alkyl halides.It is observed that the rate constants for exothermic direct proton transfer reactions, from AH+ to M or from MH+ to A, are equal to the collision rate only when the total rotational, vibrational, and electronic entropy change associated with the reaction is positive, and when the exothermicity of the reaction exceeds 2-4 kcal/mol.On the basis of rate constants in the forward and revers direction for multiple reaction pairs, internally consistent values are obtained for the proton affinities of propylene, isobutene, and cyclopentene.Protonation of trans-2-C4H8 by H3O+ (ΔRn = -10 kcal/mol, 41.84 kJ/mol) yields sec-C4H9+ exclusively.However, carbon skeletal rearrangement to the t-C4H9+ cofiguration becomes important when the ΔH of the proton transfer is + from the reaction complex.The isomerization process which also occurs upon collision of sec-C4H9+ with polar molecules is dependent on the dipole moment of M.For sec-C4H9+/trans-2-C4H8 and c-C6H11+/c-C6H10, where these isomerization processes are especially important, thermochemical information is derived from qualitative considerations of trends in reaction rates.Scales of relative proton affinities of the olefins and relative heats of formation of the alkyl ions are derived and compared with data of absolute heats of formation.Taking a value of ΔHf(t-C4H9+) = 162.1 +/- 0.8 kcal/mol (678.2 kJ/mol), the values derived for the heats of formation in kcal/mol (1 kcal/mol = 4.184 kJ/mol) follows: sec-C3H7+, 184.5 +/- 2.1; c-C5H9+, 183.8 +/- 1.9; sec-C4H9+, 176.7 +/- 2.9; c-C6H11+, 171 +/- 3; c-C5H8CH3+, 164.2 +/- 1.7; t-C5H11+, 154.6 +/- 2.0; c-C6H10CH3+, 152.7 +/- 7.1; t-C6H13+, 148.5 +/- 1.8 (the last four from an analysis of data from the literature).Heats of formation of some of the corresponding radicals, in kcal/mol, calculated from ionic heats of formation and ionization potential data, follow: C3H7, 14.8 +/- 2.6; c-C5H9, 17.5 +/- 2.4; c-C6H11, ca.6; t-C4H9 7.6 +/- 2.2.