Cyanogen photolysis

The methyl ester (100, R = CH3), derived from this A-nor acid by treatment with diazomethane, is different from the ester (102) obtained either by Favorskii rearrangement of 2a-bromo-5a-cholestan-3-one (101) or by the action of cyanogen azide on 3-methoxy-5a-cholest-2-ene (103) followed by hydrolysis on alumina. The ketene intermediate involved in photolysis of (99) is expected to be hydrated from the less hindered a-side of the molecule to give the 2j -carboxylic acid. The reactions which afford (102) would be expected to afford the 2a-epimer. These configurational assignments are confirmed by deuteriochloroform-benzene solvent shifts in the NMR spectra of esters (100) and (102). ... 

Photolysis of ethyl l-azido-A-cyanoformimidate (21) (readily prepared by the treatment of 5-ethoxytetrazole with cyanogen bromide) in benzene produces a 1.17 1 mixture (not separated) of l-(jV-cyanoethoxycarbonimidoyl)-l//-azepine(22) and 2-ethoxy-l-phenylisourea-3-carboni-trile (23).166 More recently, a similar reaction has been reported under thermal conditions.293... 

Milligan and Jacox 44 have recently reported an elegant synthesis of CF2 in an argon matrix. Carbon atoms, produced from the photolysis of cyanogen azide, were allowed to react with molecular fluorine, and the presence of CF2 was demonstrated from infrared spectra. Use of radiation effective in photolyzing F2 produced CF3 from the reaction of the CF2 with atomic fluorine. 

The X2L+ state has been observed in the photolysis of various cyanogen compounds in the near and vacuum ultraviolet. The B2 + and -42n states have been seen in the photolysis of cyanogen compounds in the vacuum ultraviolet [Mele and Okabe (692)]. Lifetimes of the A2U and B21 + states have been measured by Jeunehomme (532), Cook and Levy (236), Luk and Bersohn (650), Liszt and Hesser (641), and Jackson (518). These values are given in Table V-12. Quenching of the 02X state has been measured by Jackson (518) and Luk and Bersohn (650). 

Kroto (588) suggests that the primary process in the near ultraviolet photolysis of cyanogen azide is... 

HCo(CN)5]3- gives hydrogen and [Co(CN)5]3 on photolysis with 313 nm radiation but photolysis of the product with 254 nm radiation regenerates [HCo(CN)5]3, probably with formation of cyanogen.68... 

Simons, J.P. and Tasker, P.W. (1974). Further comments on energy partitioning in photodissociation and photosensitization Vacuum u.v. photolysis of cyanogen halides, Mol. Phys. 27, 1691-1695. 

Dichloromethyleneamino Tellurium Pentafluoride2 Equimolar quantities of tellurium chloride pentafluoride and cyanogen chloride are loaded into a 61 Pyrex flask to give a pressure of approximately 1 atm at 20°. This mixture is irradiated for 5 h with an internal low-pressure mercury lamp. The volatile products are distilled under vacuum through a series of traps at — 70°, — 110°, and —196°. The trap at — 70° contained the crude product. A series of photolysis reactions starting with 150.7 g of tellurium chloride pentafluoride yielded 82.3 g crude product that is distilled on a 100-cm spinning-band column at 76 torr yield 59.7 g (32%) b.p. 63-65776 torr. 

The existence of the cyanogen free radical (CN) in aqueous solution has not been extensively demonstrated. Oxidation of CN by OH yields an adduct (39), and photolysis of Mo(CN)83 , which was proposed to yield CN (295), has now been shown not to do so (66). The sole report that seems to stand is an ESR study in which CN, generated by reaction of S04 with CN , was detected as a spin adduct of CH2=N02 (82). 

Oxalyl chloride yields COCl radicals on photolysis and this reaction has been used to directly substitute alkanes with the chloroacyl group (equation 30). Similarly, biacetyl reacts with alkanes in a benzoyl peroxide-initiated chain reaction to give ketones in ca. 60-70% yield (equation Cyanogen... 

McGrath and Morrow " studied the reactions of both 0( D) and 0( P) with cyanogen at room temperature by flash photolysis. The 0( D) was produced by the photolysis of ozone. The reaction was monitored by absorption spectroscopy. At first, they attributed the previously unidentified ultraviolet absorption bands at 3250-3330 A to the fulminate radical (CNO), concluding that the initial step of the reaction was... 

CN radicals appear to have been those of Paul and Dalby , who studied the kinetics of disappearance of CN formed from the flash photolysis of cyanogen under varying conditions. They determined the rate coefficient for the disappearance of CN in the presence of O2 to be 5.5 x 10 I.mole . sec , assuming there was no chain reaction occurring. The nature of the products of the reation was not determined. 

Trifluoromethyl cyanide photolysis at X 1849 A results in the formation of hexafluoroethane, cyanogen and perfluoro-3-methyl-2-aza-2-butene. An initial rupture of the trifluoromethyl cyanide molecule into CF3 and CN radicals is proposed. 

The photolysis of cyanogen azide has been examined in both the vapour and solid phases. In the solid phase, ESR measurements showed the presence of NCN using filtered radiation (2800-3000 A) and triplet CNN using unfiltered light. In the vapor phase flash photolysis, the following steps have been established by kinetic spectroscopy ... 

Primary photochemical processes also may yield vibrationally excited products. Flash photolysis of cyanogen, cyanogen bromide and cyanogen iodide in each case yields a product whose absorption spectrum identifies it as a vibrationally hot CN radical with up to 6 quanta of excitation. VibrationaUy excited nitric oxide in the ground electronic state (detected by the A absorption system) is... 

Jacox et al. (17) have observed the three vibrational fundamentals of C2O in absorption in matrix-isolated C3O2 at 4.2 K which had been irradiated with 147 nm light. The same spectra were produced by photolysis of matrix-isolated cyanogen azlde/CO mixtures with wavelengths shorter than 280 nm. An absorption... 

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