O + CS reaction

Fig. 21. Relative CO vibrational energy distributions from the 0( R) + CS and CSj reactions. Open circles distribution obtained from the flash photolysis of SOj, CS2, N2O, and Ar mixtures above 200 nm, filled circles distribution obtained from the flash photolysis of NOj, CS2, and SFj mixtures above 300 nm. Both are normalized to c=I. (Ref. 145.) Triangles Data of Hancock et al. obtained from the O + CS reaction, (Ref. 147) normalized to c= 13 of the open-circle distribution. The distributions below c 5 are attributable to the O+CSj CO+ 2 reaction.

Figure 9.5 The relative population of vibrational states of CO in an O2—CS2—He flame plotted vs. the vibrational quantum number vfor different times after ignition. The COM molecules are mainly produced by the very exoergic, see Figure 5.17, O + CS reaction. The Treanor distribution, that neglects the V—T relaxation at high vs, is shown as a dashed line [adapted from S. Tsuchiya, N. Nielsen, and S. H. Bauer, J. Phys. Chem. 77, 2455 (1973)].

The O + CSe reaction is more exoergic than the O + CS reaction. However, the vibrational energy disposal is very similar as judged from the — Ay and values. Extrapolation of the linear surprisal plot again was used to estimate the populations of the lower vibrational levels for Table 2.13. 

Fig. 2. Vibrational energy distribution of the products of the reaction O + CS —> S+CO (from Gallis and Harvey ).

Key Words Ethylene oxide, Ethylene, Epoxidation, Silver, Cl promotion, Cs promotion. Promotion, Selectivity, Oxametallacycle, Adsorption, Desorption, Chemisorption, Activation energy, Ag-O bond. Reaction mechanism, Oxidation, Cyclisation, Heterogeneous catalysis, Selective oxidation, Eletrophilic oxygen. Nucleophilic oxygen. Subsurface O atoms, Ag/a-A Oj catalyst. 2008 Elsevier B.V. 

Spectroscopic and crystallographic studies of platinum-base complexes give some insight into the reactivity of the platinum compounds and their possible binding sites on DNA. The reactions of the different nucleosides or nucleotides with the chloro and aquo derivatives of O Cs- and trans-DDP have been studied by UV spectroscopy (36), raman difference spectrophotometry (37) and high pressure liquid chromatography (38). For both chloro isomers, the rates of the reactions with various nucleic acid monomers show the following trend GMP > AMP > CMP and dG > dA > dC T, The dichloro and diaquo derivatives react slowly with thymidine and UMP (37) or not at all (38, 39). 

Figure 2 Information-theoretic analysis of detailed rate data foe the reaction O + CS CO( ) + S. Panel (a) compares P(f ), the observed distributUm over CO vibrational states from the exothermic reaction, > with P°(f/) the ittstrStution expected on prior grounds. Panel (b) shows the surprisal associated with these CO(<0 concentrations as a function of f. In panel (c), the partially detailed rate constants for the endothermic reaction from selected CO v rational levels, calculated from detailed balance, are plotted against e >jhTfor T — 300 K...

I.r. laser techniques have been used to study [Fe(CO)4] in a nitrogen matrix at 20 K. Surprisingly, the quantum yield for intramolecular isomerization is greato-than the quantum yield for formation of [Fe(CO)4(N2)]. Photolysis of matrix isolated [Mo(CO)s] in the presence of Na at 20 K affords [Mo(CO)5Na)]. Under similar conditions, the analogous chromium and tungsten complexes have been detected by i.r. and Raman techniques. The photochemistry of [O(C0)5] and related species in matrices has been studied via polarized light spectroscopy. A mechanism has been proposed which accounts for almost all the experimental data on matrix-isolated [M(CO)s] (M=Cr, Mo, or W), [M(CO)5(Na)], and [M(CO)4(CS)]. Reactions occur via the following steps ... 

The formation of CO from O 4- CS has been studied by infrared chemiluminescence (analysis of steady-state populations), by the chemical laser method and by laser probe techniques. Good agreement exists for the relative populations in v = 6-15. The disagreement over the populations of the lower levels recently was resolvedby the discovery that the O 4- CSg reactions, which in most systems accompanies the O 4- CS reaction, yields CO in the lower levels. Following the suggestion of Kelley, the lower levels in Table 2.13 were obtained from extrapolation of the linear... 

Both the CO and N atom products have been observedfrom the O + CN reaction. The bimodal CO distribution is a consequence of two exit channels forming CO and N( S) or N( D) with < > of 11 and 22 kcal mole respectively. The N( D)/N( S) ratio is 4. Deconvolution of the bimodal CO vibrational distribution gives a vibrational distribution for each channel. The v = 0-3 populations from the N( D) channel correspond to Ty = 5700 K and = 0.2 the distribution for the higher CO levels corresponding to N( S) formation is strongly inverted and = 0.5. The N( D) channel is thought to proceed via dissociation of the bound NCO radical whereas, the N( S) channel involves direct reaction on a repulsive potential. Classical trajectory calculations on two empirical surfaces selected to represent the two types of reaction generally support the two-channel interpretation. The CO v) distribution from the direct component of the O + CN reaction appears to be very similar to that for O + CS or CSe. 

Carbon monoxide also is formed by the reaction of ground state O atoms with OCS the CO vibrational distribution closely resembles the A + BCD prior distribution,or a 9500 K Boltzmann distribution, and = O il- The reaction channel forming SO + CO has a 5 kcal mole" activation energy, and probably corresponds to the SO + CS channel of the O + CS2 reaction. The similarity of and for the two reactions supports this contention. The CO + SO products were not observed in molecular-beam experiment with Et = 5 kcal mole S which is the magnitude of the activation energy. 

The metal-atom reactions of Cu (98), Ag (134), and Au (135) with O provided interesting results, especially when these were compared with the results from the nickel triad (137). As shown by standard matrix-techniques, Ag forms two O2 complexes that are best formulated as Ag 02 and Ag+Oj, based on the absence of visible absorptions and the similarity of the IR spectra to those of Cs" 02 and Cs Oj (3a,b). The UV absorptions for Ag(02) and AgiOJ, at 275 and 290 nm, respectively, could be associated with the O2 and O4 anions. The shifts in the IR spectra on going from Ag(02) to Ag(04) also argue against an (02)Ag(02) formulation for the latter complex, being in the opposite sense to those observed for Pd(02)ian[Pg.139]

Insertion of a C=0, C=S or S=0 group between an amino and a hydroxy function of a 1,2-aminoalcohol produces a five-membered heterocycle with O and N as ring heteroatoms linked by -CO-, -CS- and -SO-groups. Although the reaction proceeds in two steps, it can often be carried out as a one-pot process. 

Fig. 25. Comparison between the experimental abstraction reaction H + H2O(00)(0) cross-section (solid point with error bars), and the 5D QM calculations (solid line). The 6D QM cross-sections with the CS approximation (dotted line), and the QCT data using normal (o) and Gaussian (A) binning procedures are shown.

Hori and co-workers accomplished the first synthesis of azathianaphthalene and azathiaphenanthrene in 1979 <79TL3969>. Their approach began with the formation of an olefin from o rt/20 -ni t ro b e n za 1 dehyde 43, via a Wittig reaction with an ylide and a subsequent reduction with zinc to afford cis and trans ortho-aminostyryl methyl sulfide 45. The cis-olefin was then treated with NCS, AgCKAi and KOH to yield 2-methyl- l-aza-2-thianaphthalene 47 in 41% yield. 9-Methyl- 10-aza-9-thiaphenanthrene 48a and 9-ethyl-10-aza-9-thiaphenanthrene 48b were obtained in a similar fashion in almost quantitative yields, whereas 6-benzyl-67/-d i b e n zo [ c, e] [ 1,2 J t h i azi n cs 50 were isolated in moderate yields via a 1,2-rearrangement (Scheme 13) <90TL7021>. 

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