摘要:

The mercury-photosensitized decomposition of propane was investigated from 250 to 350 °C, and at pressures from 5 to 700 Torr. The following products were identified and their initial rates of formation measured: H2, CH4, C2H4, C2H6(CH3)2CHCH(CH3)2, (CH3)2CHCH2CH2CH3, andn-C6H14. The results lead to conclusions about the mechanism. The pressure dependence of the rates were determined and interpreted in terms of a simplified steady-state treatment based on the mechanism.

ISSN:0008-4042    

DOI:10.1139/v71-087

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The results of the previous paper are analyzed to yield information about the reactions of then-propyl andi-propyl radicals. The various combination and disproportionation reactions are considered. The rate of decomposition of then-propyl radical was determined as a function of temperature and pressure, and limiting high-pressure and low-pressure kinetic parameters were obtained. The high-pressure activation energy is 32.6 kcal mol−1, and this leads to a value of 24.3 kcal mol−1for the dissociation energy of the C—C bond in then-propyl radical, to 22.2 kcal mol−1for its heat of formation, and to 99.1 kcal mol−1for the primary C—H dissociation energy in propane. Entropy changes are also calculated from the results.For the decomposition of thei-propylE∞ = 38.7 kcal mol−1, and this leads to 37.7 kcal mol−1for the C—H bond dissocation energy in this radical and to 19.3 kcal mol−1for its heat of formation. The secondary C—H dissociation energy in propane is calculated to be 96.2 kcal mol−1. Corresponding entropy changes are calculated.

ISSN:0008-4042    

DOI:10.1139/v71-088

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The crystal structure of bis-(2,4-pentanedionato)4-aminopyridinecopper(II) has been refined to anRvalue of 0.070 from photometric Weissenberg film measurements. The cell is monoclinic witha = 836 ± 3 pm,b = 1475 ± 3 pm,c = 1435 ± 3 pm, β = 112.14 ± 0.20°. The space group isP21/c(No. 14) with four molecules per cell. The density is 1.44 ± 0.01 g cm−3(measured), 1.442 ± 0.013 g cm−3(calculated). The geometry about each copper atom is approximately that of a tetragonal pyramid, with the copper atom 22 pm above the basal plane. The apex of the pyramid is occupied by an oxygen atom, the heterocyclic nitrogen is in the basal plane, and the 4-amino group is uncoordinated and hydrogen bonded to oxygen in a neighboring molecule.

ISSN:0008-4042    

DOI:10.1139/v71-089

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The Cd(I) center has been produced by both tritium β-particle irradiation and by γ-irradiation. The tritium was introduced as water of crystallization in calcium tetraacetato cadmium(II) hexahydrate in the form of THO. It is found that both forms of irradiation lead to the same center. The orientation of the hyperfine components of the Cd(I) center throws some light on the possible mechanism of its formation.

ISSN:0008-4042    

DOI:10.1139/v71-090

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Methyl 2,3,4-tri-O-acetyl-6-deoxy-6-nitro-α-D-glucopyranoside (1) was acetolyzed to give 1,2,3,4-tetra-O-acetyl-6-deoxy-6-nitro-α-D-glucopyranose (2). Compound2(or alternatively, 6-deoxy-1,2-O-isopropylidene-6-nitro-α-D-glucofuranose4) was converted into 2,3,4-tri-O-acetyl-6-deoxy-6-nitro-α-D-glucopyranosyl bromide (3) which was condensed with chloromercuri 6-benzamidopurine. De-O-acetylation of the condensation product5afforded 6-benzamido-9-(6-deoxy-6-nitro-β-D-glucopyranosyl)purine (6) which could be hydrogenated to the corresponding 6′-amino nucleoside7. Periodate oxidation of6followed by internal Henry cyclization and borohydride reduction gave 6-benzamido-9-(3-deoxy-3-nitro-α-L-ribofuranosyl)purine (10) which upon catalytic hydrogenation and subsequent de-N-benzoylation produced the title compound,12. The sensitivity of certain nitro intermediates towards alkali is commented upon.

ISSN:0008-4042    

DOI:10.1139/v71-091

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Reaction of l,5-dicarbomethoxy-2,4-dimethyl-3-oxaquadricyclane with water gave a mixture ofcis,cis,cis-andcis,cis,trans-1,2-diacetyl-3,4-dicarbomethoxycyclobutanes. The latter on treatment with acid epimerized to the correspondingtrans,trans,trans-isomer, whereas the former yielded thetrans,trans, cis-epimer together with 3,10-dimethyl-3,10-epoxy-5,8-dioxo-4,9-dioxatricyclo[5.3.0.02,6]decane which contains a new bridged ring system. The structure and stereochemistry of each compound was derived from symmetry considerations as reflected in its p.m.r. spectrum, and was facilitated by selective deuteration experiments. Vicinal and long-range spin–spin interactions between the cyclobutane ring hydrogens were deduced from pertinent p.m.r. sub-spectra using the NMRIT–NMREN computer program.

ISSN:0008-4042    

DOI:10.1139/v71-092

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A study is presented which shows how, in the Hems synthesis of two tri-ortho-substituted diphenyl ethers, the nature of theleaving groupof the substrate is important in determining yield. The yield increases in the order: OTosyl (p-OSO2C6H4CH3) < Cl < F. As well, a synthetic method, involving reaction of an activated substrate with a sodium phenoxide in dimethyl sulfoxide, has been investigated in a similar way and a number of highly-hindered diphenyl ethers, which cannot be synthesized by the Hems synthesis, have been prepared.

ISSN:0008-4042    

DOI:10.1139/v71-093

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The13C chemical shifts of acetate- and methoxyl-methyl substituents of several pyranose carbohydrate derivatives have been measured by the1H–{13C} INDOR technique. The chemical shifts (δ13C) of anomeric methoxyl-methyl resonances fall into two groups: for α-anomers (axial substituent), δ13C = 55.12–56.63 p.p.m.; for β-anomers (equatorial substituent), δ13C = 56.63–8.69 p.p.m.O-Acetyl-methyl shifts fall between 20.54–20.72 p.p.m. andN-acetyl-methyl shifts were detected between 22.98–23.08 p.p.m.

ISSN:0008-4042    

DOI:10.1139/v71-094

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The effect of added Xe on the singlet and triplet yields of monofluorobenzene vapor excited at 2670, 2520, and 2470 Å has been reinvestigated. The fluorescent yields, and hence the singlet yields, were monitored directly while triplet yields were determined by both the sensitized emission of biacetyl technique and the isomerization of olefins technique. The data obtained confirm that Xe enhances intersystem crossing in monofluorobenzene (1). However, contrary to results previously published from this laboratory (1), Xe does not quench the triplet state of biacetyl.

ISSN:0008-4042    

DOI:10.1139/v71-095

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The crystal structure of the spinel CoNi2S4was refined from X-ray and neutron powder-diffractometer data. The lattice parameter at room temperature and the positional parameter of the sulfur atom were determined as 9.424(1) Å and 0.2591(3). The neutron intensities show clearly that CoNi2S4is an inverse spinel, Ni[CoNi]S4.

ISSN:0008-4042    

DOI:10.1139/v71-096

出版商:NRC Research Press    

年代:1971

数据来源: NRC