Reaction mechanism of hydrogen cyanide catalyzed by gas‐phase titanium

To explore the details of the reaction mechanism of Ti atom with HCN, the reactive site and reactivity have been predicted first, the potential energy surfaces have been systematically studied at different theoretical levels. Four different reaction pathways and product distribution are discussed by means of the activation strain model and Curtin–Hammett principle. In addition, the structures, bonding properties and the frontier molecular orbital interaction diagrams of main stationary points were analyzed by atoms in molecules and natural bond orbital. The results show that for this system, there are four reaction pathways, in which path b (HCN＋Ti→IM1→TS1→IM2→T2b→IM4) is the most favorable pathway.     

Reaction of phenyl radicals with propyne

The potential energy surface (PES) for the phenyl + propyne reaction, which might contribute to the growth of polycyclic aromatic hydrocarbons (PAHs) under a wide variety of reaction conditions, is described. The PES was characterized at the B3LYP-DFT/6-31G(d) and B3LYP-DFT/6-311+G(d,p) levels of theory. The energies of the entrance transition states, a direct hydrogen-transfer channel and two addition reactions leading to chemically activated C(9)H(9) intermediates, were also evaluated at the QCISD(T)/ 6-311G(d,p) and CCSD(T)/6-311G(d,p) levels of theory. An extensive set of unimolecular reactions was examined for these activated C(9)H(9)(dagger) intermediates, comprising 70 equilibrium structures and over 150 transition states, and product formation channels leading to substituted acetylenes and allenes such as PhCCH, PhCCCH(3), and PhCHCCH(2) were identified. The lowest energy pathway leads to indene, a prototype PAH molecule containing a five-membered ring. The title reaction thus is an example of possible direct formation of a PAH containing a five-membered ring, necessary to explain formation of nonplanar PAH structures, from an aromatic radical unit and an unsaturated hydrocarbon bearing an odd number of carbons. Extensive Supporting Information is available.     

Reaction of nitroxyl radicals with dichlorocarbene

Conclusions The reaction of aromatic nitroxyl radicals with dichlorocarbene, generated under phase transfer catalysis conditions, leads to the corresponding hydrazine derivatives through the abstraction of the oxygen atom from the nitroxyl radicals and formation of aminyl radicals.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 470–472, February, 1989.     

Reaction of t-butoxy radicals with norbornadiene

95 percent of the reaction of t-butoxy radical with norbornadiene occurs by radical addition followed by rearrangement to nortricyclyl and 7-t-butoxynorbornenyl products; the remainder includes a novel radical rearrangement involving a 1,3-H shift and some radical abstraction observed for the first time.     

Reaction of methyl radicals with haloalkanes

The kinetics of reactions involving halogen atom abstraction from haloalkanes by methyl radicals have been studied in the gas phase. Arrhenius parameters for halogen atom transfer were determined relative to those for methyl radical combination:

Reaction of enol type acyl cyanide with o-aminophenol

The reaction of 7-chloro-4-(2-cyano-2-hydroxyvinyl)tetrazolo[1,5-a]quinoxaline 2a with o-aminophenol gave 7-chloro-4-(b-hydroxyphenylcarbamoylmethylene)4,5-dihydrotetrazolo[1,5-a]quinoxaline 4 , while the reaction of compound 2a with o-aminophenol hydrochloride afforded 4-[2-(2-benzoxazolyl)-2-hydroxyvinyl]-7-chlorotetrazolo[1,5-a]quinoxaline 5 , whose acetylation provided 4-[2-acetoxy-2-(2-benzoxazolyl)vinyl]-7-chlorotetrazolo[1,5-a]quinoxaline 6 . The behavior in a deuteriodimethyl sulfoxide or deuteriotrifluoroacetic acid solution is described for compounds 4–6 .     

Reaction of methyl radicals with atomic oxygen

The reaction of hydrogen atoms with diazomethane was used as a source of methyl radicals to study the reaction of oxygen atoms with methyl radicals. This investigation verifies directly the earlier results that formaldehyde is a major product and that the rate constant is greater than 3×10^?11cm³ molecule^?1 sec^?1.     

Reaction of phosphonyl radicals with substituted orthobenzoquinones

Conclusions The reaction of a diethylphosphonyl radical with substituted orthobenzoquinones proceeds in two directions: addition to an oxygen atom, to form a phenoxyl-type radical, or to the ring, to form a cyclohexadienyl-type radical.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2563–2569, November, 1987.     

Reaction of diisopropyl benzeneboronate with free radicals

Summary When diisopropyl benzeneboronate is treated with free radicals the initially formed diisopropyl benzeneboronate radical undergoes decomposition, which is reflected in the structure of the obtained polymer.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 367–368, February, 1965     

Reaction of di-t-butyliminoxy radicals with organometallic compounds

Reactions of the title iminoxy radical 1 with Grignard and organolithium reagents RM yield initially di-t-butyl ketoxime 2 (in salt form) together with the radical R-. This radical R- can combine with unreacted iminoxy radical on oxygen to give the oxime ether 3. For steric reasons attack on nitrogen is difficult and therefore nitrone 6 is not formed, or in trace amounts only. The even more hindered attack on carbon is never observed, i.e. there is no formation of (intermediary) nitroso compounds. The relatively reactive methyl and phenyl radicals can abstract hydrogen from the solvent (diethyl ether). In this way α-ethoxyethyl radicals are formed, which can combine with the iminoxy radical on oxygen, yielding the acetal-like oxime ether 7.     

Reaction of undecyl radicals with aromatic hydrocarbons

A competition method (R^.+O₂RO ₂ ^. , R^.+XHRH+X^.) is proposed to measure the relative rate constants for the interaction of alkyl radicals with different organic compounds. Partial (per C–H bond) rate constants have been determined for the reaction of undecyl radicals with cumene, ethylbenzene and toluene.

---

(R^.+O₂RO ₂ ^. , R^.+XHRH+X^.), . ( C–H ) , .

     

Reaction of iminoxyl radicals with triphenylmethylcarbonium salts

Russian Chemical Bulletin -