Generation of radicals in a flow reactor; ions and neutrals

Matthew Jon Lenington, Purdue University

Abstract

Topological control of electronic spin states in disjoint diradicals meta- and para-bisallyl benzenes was studied in the gas phase. Electron affinities of the diradicals were determined by simple kinetic method analysis of the branching ratios of collisionally dissociated diradical/reference heterodimer anions. Electron affinities derived from these thermochemical measurements were used to assess the electronic spin state of the diradicals. para-bisallyl benzene has an electron affinity of 0.84 ± 0.15 eV with a singlet ground state. meta -bisallyl benzene has an electron affinity of 0.90 ± 0.15 eV with a triplet ground state. Topological control of electronic spin states in meta- and para-nitrophenylallyl anions was investigated by flow tube reactivity, low-pressure low-energy exothermic reactivity, and flow tube kinetics studies. Reactivity of the meta-isomer is consistent with closed shell anionic electronic structure while reactivity of the para-isomer is consistent with an open shell triplet electronic structure. Generation of acylnitrene anions by oxide transfer from substituted quinoline N-oxide anions to nitriles was investigated. Rates of quinoline N-oxide depletion as a function of electron withdrawing group functionalization was studied by flow tube kinetic reactivity with an array of neutral gases. Electron transfer to nitriles with high electron affinities, such as 4-cyanopyridine and tetracyanoethylene, is observed. A microwave discharge source for atomic radicals was developed for use in conjunction with the flow reactor. Atomic nitrogen and fluorine were generated and characterized by flow tube reactivity. Atomic nitrogen was used to generate phenide anion by addition to phenyl nitrene anion and benzoyl nitrene anion, followed by loss of N2, and N2 and CO respectively. Atomic fluorine was used to generate phenyl radical by hydrogen atom abstraction from benzene, characterized by the formation of F−(HF) n clusters.

Degree

Ph.D.

Advisors

Wenthold, Purdue University.

Subject Area

Organic chemistry

Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server
.

Share

COinS