The effects of electronic buttressing on the conformations of some orthodisubstituted benzenes

1972 ◽  
Vol 25 (4) ◽  
pp. 811 ◽  
Author(s):  
RI Herrmann ◽  
ID Rae
Keyword(s):  
Magnetic Resonance ◽  
Benzene Ring ◽  
Aromatic Ring ◽  
Proton Magnetic Resonance ◽  
The Other ◽  
Magnetic Resonance Spectra

When one of a pair of substituents ortho to each other on a benzene ring is conjugated with an appropriate para substituent, it is pulled towards coplanarity with the aromatic ring and the other substituent has to take a greater share of the twisting necessary to avert steric conflict. This effect, termed electronic buttressing, is demonstrated in the proton magnetic resonance spectra of 5-dimethylamino-2- nitroanilines, 5-substituted methyl 2-nitrobenzoates, and 4-substituted 1,2-dinitrobenzenes. In this latter group the size of the effect is shown to depend on the conjugative ability of the 4-substituent.

Proton magnetic resonance spectra of the mannans of some new species of Hansenula and their phylogenetic significance

1970 ◽  
Vol 16 (6) ◽  
pp. 445-448 ◽  
Author(s):  
J. F. T. Spencer ◽  
P. A. J. Gorin ◽  
L. J. Wickerham
Keyword(s):  
New Species ◽  
Magnetic Resonance ◽  
Phylogenetic Relationships ◽  
Proton Magnetic Resonance ◽  
Hansenula Polymorpha ◽  
The Other ◽  
Phylogenetic Significance ◽  
Lower Content ◽  
Haploid Species ◽  
Magnetic Resonance Spectra

The proton magnetic resonance spectra of the mannose-containing polysaccharides from some new species of Hansenula were obtained and used as an aid in establishing their phylogenetic relationships to other members of the genus. The spectrum of the mannan from Hansenula dimennae is identical with that of the mannan from Hansenula californica. These two haploid species are taxonomically closely related and are adjacent on the same line of the phylogenetic diagram according to Wickerham. Hansenula saturnus var. subsufficiens mannan has a spectrum like those of the mannans of some strains of Hansenula mrakii and Hansenula beijerinckii. The new species Hansenula henricii, Hansenula nonfermentans, and Hansenula glucozyma all form mannans with spectra having characteristic signals at about τ4.24 and τ4.38, as do the spectra of the mannans formed by the other species on the same phylogenetic line, Hansenula polymorpha, Hansenula minuta, and Hansenula wickerhamii. These species have, relatively, DNA's with the highest guanine and cytosine percentages in the genus. Hansenula platypodis, a species which, unlike other Hansenula species, forms ascophores and anastomoses, has DNA with a lower content of guanine plus cytosine. The spectrum of H. platypodis mannan is like that of H. minuta mannan, with the exception of two small signals at τ4.44 and τ4.48 which do not occur in the spectrum of H. minuta mannan.

Aromatic amides. VI. Proton magnetic resonance spectra of some 2-substituted 1,3-phenylenediamines and their N,N'-diacyl derivatives

1971 ◽  
Vol 24 (2) ◽  
pp. 413 ◽  
Author(s):  
BD Andrews ◽  
ID Rae
Keyword(s):  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Aromatic Ring ◽  
Proton Magnetic Resonance ◽  
New Technique ◽  
A New Technique ◽  
Magnetic Resonance Spectra ◽  
Amide Protons

A number of 2-substituted 1,3-phenylenediamines and their N-acyl and N,N?-diacyl derivatives have been prepared and the proton magnetic resonance spectra examined for evidence that hydrogen bonding between the amide protons and the 2-substituents can occur so as to constrain two amido groups to coplanarity with the aromatic ring. The nitro and methylsulphonyl substituents behave in this way. Weaker, but still effective, dual hydrogen bonding to methoxycarbonyl, chloro, methoxy, and methylthio substituents is observed. A new technique is described for performing the Hoffman degradation of the bis-amide of 2- nitroisophthalic acid to 1,3-diamino-2-nitrobenzene.

REACTIONS OF ORGANOTIN COMPOUNDS: VI. THE REACTIONS OF TIN HYDRIDES WITH PERFLUOROVINYL TIN COMPOUNDS

1966 ◽  
Vol 44 (2) ◽  
pp. 179-189 ◽  
Author(s):  
A. D. Beveridge ◽  
H. C. Clark ◽  
J. T. Kwon
Keyword(s):  
Magnetic Resonance ◽  
Ultraviolet Irradiation ◽  
Proton Magnetic Resonance ◽  
Hydrogen Exchange ◽  
The Other ◽  
Organotin Compounds ◽  
Tin Compounds ◽  
Other Hand ◽  
Vinyl Group ◽  
Magnetic Resonance Spectra

The reactions of methyltin hydrides with methylperfluorovinyltin compounds have been examined under heat or ultraviolet irradiation. In no case is there evidence of addition to the C=C bond. Instead, extensive reduction of the vinyl group occurs to give cis-1,2-difluorovinyltin derivatives as the principal products, with smaller amounts of the trans-1,2-difluorovinyltin isomers, 2,2′-difluorovinyltin compounds, and products containing one or more —C2H2F groups. Trimethyl- or dimethyl-tin fluoride is formed quantitatively from the corresponding hydride. In the reaction of dimethyl bis(perfluorovinyl)tin with dimethyltin dihydride, vinyl-hydrogen exchange occurs at 60° in the dark to give dimethylperfluorovinyltin hydride, while under ultraviolet irradiation partially fluorinated vinyltin compounds are formed. On the other hand, no reaction takes place between dimethyl bis(perfluorovinyl)tin and 2 moles of trimethyltin hydride in the dark at 50°, but under ultraviolet irradiation at 25°, partial vinyl-hydrogen exchange occurs, accompanied by reduction, to yield both trimethyl and dimethyl partially fluorinated vinyltin compounds. The infrared and proton magnetic resonance spectra of the products are discussed.

The preparation of 2-Fluoro-5-nitrobenzonitrile and the proton magnetic resonance spectra of some compounds containing the N-(2-Cyano-4-nitrophenyl) group

1967 ◽  
Vol 20 (8) ◽  
pp. 1663 ◽  
Author(s):  
JFK Wilshire
Keyword(s):  
Amino Acids ◽  
Magnetic Resonance ◽  
Nitro Group ◽  
Proton Magnetic Resonance ◽  
Cyano Group ◽  
Aromatic Nucleus ◽  
Heteroaromatic Compounds ◽  
Magnetic Resonance Spectra

2-Fluoro-5-nitrobenzonitrile, an analogue of 1-fluoro-2,4- dinitrobenzene, in which the 2-nitro group has been replaced by a cyano group, has been prepared and made to react with several amines, amino acids, and NH-heteroaromatic compounds. The proton magnetic resonance spectra of some of the resultant N-(2-cyano-4-nitrophenyl) derivatives were compared with the spectra of the corresponding N-(2,4- dinitrophenyl) derivatives and furnish further evidence that the ortho nitro group of the latter derivatives is rotated out of the plane of the aromatic nucleus.

Investigation and Identification of the Bromination Products of Dimethoxyamphetamines

1976 ◽  
Vol 59 (5) ◽  
pp. 1162-1169
Author(s):  
Keith Bailey ◽  
Denise R Gagné ◽  
Richard K Pike
Keyword(s):  
Magnetic Resonance ◽  
Qualitative Analysis ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Infrared Spectra ◽  
Proton Magnetic Resonance ◽  
Positive Identification ◽  
Aromatic Bromination ◽  
Layer Chromatography ◽  
Magnetic Resonance Spectra

Abstract The qualitative analysis of the aromatic bromination products of the 6 isomeric dimethoxyamphetamines and their hydrochloride or hydrobromide salts is described. Their ultraviolet, mass, and proton magnetic resonance spectra are not sufficiently different for distinction but infrared spectra allow a positive identification to be made and reference spectra are provided for the bromination products of 2,4-, 2,5-, 2,6-, 4,5-, and 3,5-dimethoxyamphetamines. The application of gas-liquid and thin layer chromatography for the analysis of these products is discussed. The bromination of 2,3-dimethoxyamphetamine consistently gave mixtures which could not be separated satisfactorily; spectra are included for completeness of the comparison of products.

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