Hydrogen sulphide, photolysis

The SH radical is the only diatomic hydride of the first two periods whose vibrational constants are completely unknown and one of the few common hydrides for which not even an approximate value of the dissociation energy is available. Its spectrum does not appear readily and only one band, the o—o band of the i/ — i7 transition, has ever been observed.It is well known that hydrogen sulphide can be decomposed photochemically into its elements, and although other mechanisms have been proposed it is probable that the primary decomposition is to H and SH. For this reason the flash photolysis of H,S was studied as a probable source of the SH radical,... 

Another synthesis of azepines from azides involved the photolysis or thermolysis of aryl azides in the presence of nucleophiles. The photolysis of phenyl azide in diethylamine yielded (34%) 2-diethylamino-3/f-azepine (311) °. In the same manner 2-substituted azepines were obtained from phenyl azide and liquid ammonia, aniline and hydrogen sulphide . 

P), and by Wooley and Cvetanovic [13] in which photolysis of hydrogen sulphide in the presence of large amounts of carbon dioxide produced fully thermalized hydrogen atoms. 

Another type of commercial hop extract is made by borohydride reduction of an isomerized extract of a-acids and is claimed to be less sensitive to light than a normal isomerized extract [124]. When beer, particularly lager beer, is exposed to sunlight in clear bottles it develops an unpleasant sun-struck flavour due to the formation of isopentenyl mercaptan (98). It is envisaged that photolysis of isohumulone cleaves the isohexenoyl side-chain to form a 3-methylbut-2-enyl radical which reacts with hydrogen sulphide, or any available thiol, in the beer to produce (98) [125]. 

Hexafluoroacetone has been used as a photochemical source of trifluoro-methyl radicals in kinetic studies dealing with attack of the latter on ethylene," di-isopropyl ketone, methylchlorosilanes, the methylsilanes MejSi, MejSiF, MeaSiFj, and MeSiFj, methyl acetate and deuteriated methyl acetates, dimethyl and di-isopropyl ether, tetramethyltin (less precise data were obtained with McsB, Me Si, and Me Ge), methyl formate, and hydrogen sulphide, deuterium sulphide, hydrogen chloride, and deuterium chloride. The photolysis of hexafluoroacetone alone has received further detailed attention and trifluoromethyl radicals thus generated have been shown not to attack sulphur hexafluoride even at temperatures up to 36S °C. ... 

The photoelectron spectrum and ab initio SCF calculations of sulphur dichloride have been presented, and an assignment of observed states of the SCF radical cation was attempted.71 For the SC12 ground state the calculated dissociation energy, dipole moment, total atomic population, and total d -orbital population were given. The photolysis of sulphur monochloride with a series of saturated aliphatic hydrocarbons has been shown to yield alkyl chlorides, di- and poly-sulphides, hydrogen chloride, and elemental sulphur.72... 

The rate coefficients for the gas-phase reaction of OH radicals with dimethyl sulphide were determined using a relative rate method. The kinetic experiments were performed at a total pressure of 1000 mbar diluent gas (N2, synthetic air, or N2/O2 mixtmes), at three different O2 partial pressure ( 0 mbar, 205 mbar, and 500 mbar) and six different temperatures (250 K, 260 K, 270 K, 280 K, 290 K, and 299 K). The photolysis of hydrogen peroxide (H2O2) was used as the OH radical source ... 

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