Aliphatic hydrocarbons photolysis

Aromatic nitrenes are as selective in their insertion reactions as carbonyl nitrenes. In phenyl nitrene the insertion yields into primary, secondary and tertiary C—H bonds are in the approximate ratios 1 10 100 . Aromatic nitrenes insert into aromatic G—H bonds about as efficiently as into secondary G—H bonds of aliphatic hydrocarbons photolysis and thermolysis of 2-azidobiphenyI produces... 

Though most of the oxygen in the atmosphere has been formed by photosynthesis in plants, some is produced by photolysis of water vapour in the vacuum ultraviolet region A <200 nm. Photolysis of N2, NO, N02, NHa, CO, 002 and small aliphatic hydrocarbons (alkanes) set up complex reactions in the upper atmosphere. 

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... 

Arylalkenes, such as stilbene derivatives, are important model compounds for the study of the E Z photoisomerization.529 559 560 The compounds absorb significantly over 250 nm, therefore direct irradiation is technically simple. Photolysis of unsubstituted stilbene in aliphatic hydrocarbons at 313 nm affords a photostationary state (PSS) consisting of 93% of (Z)-stilbene and 7% of ( )-stilbene (Scheme 6.4).112 In addition, a photoinduced 67t-electrocyclic (Section 6.1.2) formation of dihydrophenanthrene with a quantum yield of < > 0.10 competes with (Z)-stilbene isomerization ([Pg.232]

Photolysis of the carbodiimide complex 395 in hydrocarbon solvents similarly effects C H activation, via initial dissociation of the carbodiimide ligand to afford Tp Rh(CNCH2 Bu) as the active species. The reaction proceeds in a variety of neat aliphatic hydrocarbons, with apparently exclusive selectivity for the primary C H of terminal methyl groups. This includes the case of chloroalkanes, for which no oxidative addition of the C Cl bond is observed. Competition is, however, noted for aromatic substrates bearing methyl substituents, " with both benzylic and aromatic activation proceeding under kinetic control, though the aromatic activation products are thermodynamically favoured. Thus, toluene affords a kinetic mixture of aryl and benzyl complexes, which thermally redistributes to a 2 1 mixture of meta and para isomers of the aryl complex, while mesitylene yields a 3 1 mixture of the mesityl and benzyl complexes. 

Irradiation of aliphatic thiols, sulfides, and disulfides with a mercury lamp produces gaseous products identified by the mass spectrograph. Thiols are the least stable to light, with the formation of hydrogen95-129 as the main product. Sulfides and disulfides yield, as the predominant products, saturated hydrocarbons of structures corresponding to the smallest alkyl radical attached to sulfur. Haines et al.95-97 have offered a mechanism to explain the predominant production of hydrogen during photolysis of thiols. 

Another physical study which used flash photolysis relates directly on the MB/amine system. Kayser and Young (36) examined a more extensive series of amines, both aromatic and aliphatic, than Steiner (33). Their results are shown in Table 3. Excellent correlation was obtained between the amine ionization potential and the rate constant for MB quenching the slope of the logarithmic plot was -1.75 eV-1- This value is relatively small compared to some oxidizing excited states (e.g. hydrocarbons, -17 eV l (37)), but it is similar to the value observed for ketone triplet quenching by amines (-1.5 eV l (38)), and does indicate that the quenching interaction becomes more facile as... 

In a somewhat different kind of reaction 2-butyl-3-propyl-oxaziridine has been reported to be converted to 3,5-diethyl-4-propylpyridine by heat a similar result had been reported previously. Oxaziridines have been implicated as the precursors of lactams and amides in the photolysis of aliphatic nitro compounds in hydrocarbons. ... 

The addition of sodium to aromatic hydrocarbons produces only the corresponding radical anion [121]. Alkali metals, however, dissolve in aliphatic ethers, e.g. tetrahydrofuran, dioxan, producing the characteristic blue colour [122], The solutions are diamagnetic because of the formation of higher ion pairs. Flash photolysis of solutions of sodium in ethers forms the ion pair consisting of the solvated electron and a sodium cation [123]. Three transients are formed in the flash photolysis of sodium pyrenide in tetrahydrofuran [124]. These have been identified as the solvated electron, es"oiv. the ion pair, esoiv> Na, and the sodium atom, Na°. Rate coefficients of reactions of es ,iv with various compounds relative to the rate of reaction with NjO have been determined recently by the 7-radiolysis of 2-methyl-tetrahydrofuran [125]. 

Analysis methods for the determination of hydroperoxides and hydroxyhydro-peroxides in reaction mixtures were developed and applied to photolysis mixtures of aliphatic and aromatic hydrocarbons, carbonyls, alcohols and halogenated hydrocarbons. HPLC with chemiluminescence, electrochemical and fluorescence detection was used for selective detection of hydroperoxides and hydroxohydro-peroxides and gas chromatography with mass spectrometric and flame ionisation detection for the analysis of all reaction products. 

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