Photochemistry of aryl azides: detection and characterization of a dehydroazepine by time-resolved infrared spectroscopy and flash photolysis at room temperature

1987 ◽  
Vol 109 (15) ◽  
pp. 4723-4726 ◽  
Author(s):  
Charles J. Shields ◽  
Douglas R. Chrisope ◽  
Gary B. Schuster ◽  
Andrew J. Dixon ◽  
Martyn Poliakoff ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Room Temperature ◽  
Flash Photolysis ◽  
Aryl Azides ◽  
Time Resolved ◽  
Time Resolved Infrared Spectroscopy

scholarly journals Time-Resolved Infrared Spectroscopy in Supercritical Fluids

1999 ◽  
Vol 19 (1-4) ◽  
pp. 133-139 ◽  
Author(s):  
Michael W. George ◽  
Martyn Poliakoff ◽  
Xue-Zhong Sun ◽  
David C. Grills
Keyword(s):  
Infrared Spectroscopy ◽  
Supercritical Fluids ◽  
Room Temperature ◽  
Noble Gas ◽  
Fast Time ◽  
Metal Carbonyls ◽  
Time Resolved ◽  
Organometallic Reactions ◽  
Time Resolved Infrared Spectroscopy ◽  
First Time

We have used fast Time-resolved Infrared Spectroscopy (TRIR) to probe organometallic reactions in supercritical fluids on the nanosecond time-scale. This has allowed us to identify, for the first time in solution at room temperature, organometallic noble gas complexes which are formed following irradiation of metal carbonyls in supercritical noble gas solution. We have found that these complexes are surprisingly stable and have comparable reactivity to organometallic alkane complexes. We have also studied the coordination of CO2 to metal centres in supercritical CO2 (scCO2) and provide the first evidence for the formation and reactivity of ɳ1-O bound metal CO2 complexes in solution at or above room temperature.

Kinetic and Spectroscopic Studies on Acyl Radicals in Solution by Time-Resolved Infrared Spectroscopy

1995 ◽  
Vol 48 (2) ◽  
pp. 363 ◽  
Author(s):  
CE Brown ◽  
AG Neville ◽  
DM Rayner ◽  
KU Ingold ◽  
J Lusztyk
Keyword(s):  
Infrared Spectroscopy ◽  
Rate Constant ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Spectroscopic Studies ◽  
Kinetic Properties ◽  
Acyl Radical ◽  
Time Resolved ◽  
Acyl Radicals ◽  
Time Resolved Infrared Spectroscopy

A number of acyl radicals, RĊ=O, have been generated in hexane or di -t-butyl peroxide as solvent at room temperature by 308 nm laser flash photolysis, and their spectroscopic and kinetic properties have been examined by time-resolved infrared spectroscopy. The C=O stretching frequencies for the RĊ=O radicals are found to be higher than those of the corresponding aldehydes, RCHO, by between 108 and 128 cm-1, an effect attributed to a higher C=O bond order in the radicals. For the RĊ=O radicals some typical values of vC =O are: CH3Ċ=O, 1864 cm-1; (CH3)3CĊ=O, 1848 cm-1; and C6H5Ċ=O, 1828 cm-1, while the corresponding acylperoxyl radicals, RC(O)OO, formed by reaction with oxygen have vC =O values of 1838, 1840 and 1820 cm-1, respectively. The acyl radicals exhibit a reactivity towards a variety of substrates that is roughly comparable to that of simple alkyl radicals. For reactions of the benzoyl radical some typical rate constants/M-1 s-1 are: CCl4, 6.0x104; C6H5SH, 4.8×107; CCl3Br, 2.2×108; Tempo, 1.1×109; and oxygen, 1.8×109. Alkanoyl radicals have a rather similar reactivity to benzoyl. The propanoyl radical reacts with tributyltin deuteride with a rate constant of 3×105 M-1s-1. The hex-5-enoyl radical undergoes a 5-exo-trig cyclization to form the 2-oxocyclopentylmethyl radical with a rate constant of 2.2×105 s-1, a value which is almost identical to that for cyclization of the hex-5-enyl radical. It is hoped that our kinetic data will prove useful in the planning of organic synthetic strategies which involve acyl radical chemistry.

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