Effect of kinetic energy on the ionic reactions in propylene and cyclopropane

Abstract

The reactions of the C3He+ molecule-ion in the propylene and cyclopropane systems have been studied as a function of ion exit energy in a single-stage mass spectrometer. The yields of the products 03 +, C4H7+ C4H8+, and C5H3+ decrease markedly with increasing ion energy with a number of low mass products, C3H6+, C3H4+, C3H3+ and, in low yield, C2 ions, being formed at high ion energies. The yield curves for each of these latter products show definite energy thresholds characteristic of endothermic reactions and comparison of these thresholds with calculated reaction heats provides some information on the reactions occurring.

Photoionization of propylene, cyclopropane, and ethylene. The effect of internal energy on the bimolecular reactions of C2H+4 and C3H+6

“…These' product~ have not bee n observed in studies involving electron impact ionization of cyclopropane under th ermal conditions [9,13,17] and were not observed in th e present s tudy at any ph oton e ne rgy. This result indi cates that eve n thou gh a fraction of the C:IHt ions resultin g from photoionization of cyclopropane at 11.7 eV may be in th e seco nd elec troni c state (11.07 e V) [37J th e add itional e nergy is not effe ctive in overcoming th e e ne rgy barrier for th ese processes .…”

“…Th e overall reaction of ClHt with ClHG has probably bee n subj ected to mo re sc rutiny b y mass spectrometry in various laboratories [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] than any oth er reacti on involvin g co mple x olefini c ions. Wh e n th e co lli s ion fre qu e ncy is s ufficie ntl y low to prec lud e s ta bili za ti on of Ci Ht2 co mpound ion produced vi a process (1).…”

“…Other investi gators have , o n occasion , s ugges ted uniqu e stru ctures for those C6 H t/ co mpound ions which unimolec ularly fragme nt at low pressures [1 5]. How ever, as pointed out by Harriso n [13,17], and as indi cated in a recent stud y in thi s laboratory [34], the modes of decomposition of a co mpound ion de p en d critically on the inte rnal energy of the sys tem . Many diffe r~nt isomeric stru ct ures may exist und e r th ese conditi ons, and th e dissociation is likely to occur from any or all of these configuration s. Therefore, it is not 'surprising that ten or more C;H 12 iso meric products were recovered when th e photoionization of propylene was carri ed out in a closed sys tem in the presence of (CH:daN (LP.…”

Mass Spectrometric Study of Positive Ion-Molecule Reactions in the C3H6and Ar Mixtures Inside the High Pressure Ion Source

“…Primary ions were produced by the electrons with the energy of 300 eV and then they reacted with neutral gas molecules to form secondary and higher rate ions. The following primary and secondary ions: CH In the mixtures of propene with argon, ionmolecule processes can take place according to the reaction scheme [3,4,9,10,14,18,19]:…”

“…Aquilanti et al investigated ionic reactions in gaseous butenes [8]. Herod and Harrison used the mass spectrometer with a pulsed electron beam to study the reactions in propene [9]. The ionmolecule reactions in pure propene have been investigated by Peers using the 60…”