摘要:

The irradiation of triacetic acid lactone in various solvents results in novel rearrangement to β-methyl-glutaconic acid derivatives. In benzene solution an efficient conversion to β-methylglutaconic acid anhydride occurs while in methanol solution a mixture of products is obtained whose structures represent retention and rearrangement of the original carbon skeleton. Results obtained from irradiation of the corresponding methyl ether of triacetic acid lactone in methanol solution are also described.

ISSN:0008-4042    

DOI:10.1139/v70-447

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The flow patterns around the mercury drop at the positive and negative polarographic maxima have been investigated by suspensions of activated carbon particles and laser interferometry. The accepted patterns due to Antweiler have been shown to require modification. Specifically the positive maximum flow is a downflowing annulus with a gently upwelling interior below the equator of the drop and the negative maximum flow is a torroidal whorl surrounding the drop. Speeds of particles were recorded by motion picture photography and concentration changes by interferograms.

ISSN:0008-4042    

DOI:10.1139/v70-448

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The thermal analyses of Cd2(OH)3X type of basic halides reveal that the decomposition occurs via a two-step dehydroxylation pattern, yielding CdOHX as an intermediate product after the initial mode. These results suggest that Cd2(OH)3X is an addition compound of the hydroxide and the 1:1 hydroxy-halide, i.e. Cd(OH)2•CdOHX. Calorimetric measurements along with related enthalpy values for the decomposition reaction are given.The kinetics of thermal decomposition of the compounds are classified into two main groups: (i) two-dimensional contracting plate model equation and (ii) first-order rate law.The infrared spectral data of thirteen Cd and Zn basic halides in the frequency region 4000–250 cm−1are presented with their assignments.

ISSN:0008-4042    

DOI:10.1139/v70-449

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The fulvic acid molecular weight fraction studied has two general types of carboxyl groups, one of which is ortho to phenolic —OH groups. The number of each type per gram of fulvic acid has been measured. The acid ionization equilibrium of each type has been calculated as a function of its degree of ionization in 0.1 mKCl at 25.0 °C. In both cases the acid strength decreases with increasing degree of ionization. The sample used shows the potentiometric titration behavior expected of a low molecular weight polyelectrolyte.

ISSN:0008-4042    

DOI:10.1139/v70-450

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The infrared and nuclear magnetic resonance spectra of a number of allyl-, but-3-enyl-, crotyl-, and vinyl-tin compounds in dimethylsulfoxide have been examined and compared with measurements made on solutions in methylene chloride and carbon tetrachloride. It is concluded from the changes which occur in the positions of the ν(C=C) bands and in the chemical shifts of the olefinic protons that there are no significant π-interactions between the d orbitals on tin and the olefinic π-systems.

ISSN:0008-4042    

DOI:10.1139/v70-451

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The kinetics of the oxidation ofp-toluenesulfonic acid by aqueous potassium permanganate have been studied in perchloric acid solutions ranging from 0.296 to 3.16 MHClO4. Below 1 MHClO4the rate law is found to be,v = k3[Arene][MnVII]h0while above 2 MHClO4it isv = k2[Arene]h0. The values obtained fork3andk2are 8.09 ± 0.25 × 10−4and 1.19 ± 0.13 × 10−7 M−1 s−1respectively.

ISSN:0008-4042    

DOI:10.1139/v70-452

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

A simple modification is described which enables a Varian HA-100 spectrometer to be used routinely for1H–{1H} internuclear double resonance experiments. Several examples are given to illustrate the results which may be obtained via this technique, with particular emphasis on carbohydrate derivatives.

ISSN:0008-4042    

DOI:10.1139/v70-453

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Electron spin resonance studies have been performed on methyl radicals stabilized on the surface of porous VYCOR glass. As previously reported, two very different methyl radicals, denoted Me and Me′, were seen. Results indicate that the radical Me′ is most probably weakly bound to the boroxane group (=B—O—B=) which is prominent on the surface of high temperature (700–900 °C) pretreated porous VYCOR glass. Four satellite lines about each Me line, denoted previously as radical X, were observed when the surface was pretreated at lower temperatures (400–500 °C). In an earlier publication radical X was attributed to the interaction between methyl radicals and the isotopic surface species11B. In this study two additional satellite lines about each Me line are reported as well as a reassignment of the origin of all satellite lines. Four of the six satellite lines have been assigned to forbidden "spin–flip" transitions while the other two have been assigned to direct interaction between methyl radicals and the surface hydroxyl protons. Support for the irreversibility of high temperature dehydroxylation of porous VYCOR glass is also presented.A partial resolution of the second-order splitting of each of the central pair of lines was achieved for the normal methyl radical. The value of the second-order splitting was between 220 and 230 mG. The linewidths of the two central lines were measured at 77 °K. The samples were then allowed to warm up to various temperatures and then recooled to 77 °K. The linewidths were smaller after completing this cycle. Storage of the sample at 77 °K allowed the linewidths to return to their original values. These linewidths effects are explained by postulating the existence of two different types of potential wells on the surface.

ISSN:0008-4042    

DOI:10.1139/v70-454

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Model calculations are reported for ArF2, KrF2, XeF2, ArCl2, KrCl2, and XeCl2. The approach is to compare the energies of a number of valence-bond structures for each molecule. The calculations use Slater-type radial functions and simplify the electron repulsion integrals with the Mulliken approximation. Energies are optimized by varying the d orbital exponent and a parameter which governs the ionic character of the covalent bonds. For all the molecules it is found that the structures such as (X—M+X− + X−M+—X) and X−M2+X−, which maintain the octet rule and exclude the use of d orbitals, are less stable than the structure X—M—X which implies localized electron-pair bonds based on pd hybrids at the noble-gas atom M.Approximate molecular wave functions are obtained from a configuration interaction calculation, and the general conclusion is that the valence-bond structures incorporating d orbitals become more important as the atomic number of the central atom increases. A preliminary study of the role of theorbital is also presented, but it seems this orbital contributes mainly as a polarization effect.

ISSN:0008-4042    

DOI:10.1139/v70-455

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The structures of sepedonin, 3,6,9-trihydroxy-3-methyl-1,3,4,7-tetrahydrocyclohepta[c]pyran-7-one, and its two dimethyl ether derivatives, as well as anhydrosepedonin and its three dimethyl ether derivatives, are unequivocally established from proton magnetic resonance and nuclear Overhauser enhancement parameters.

ISSN:0008-4042    

DOI:10.1139/v70-456

出版商:NRC Research Press    

年代:1970

数据来源: NRC