Ionization of sulfonic acids and dimethylsulfoxide basicity. A 13C nuclear magnetic resonance and calorimetric study

1989 ◽  
Vol 67 (12) ◽  
pp. 2148-2152 ◽  
Author(s):  
Robert L. Benoit ◽  
Monique Fréchette ◽  
Danielle Boulet
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Bulk Water ◽  
Calorimetric Study ◽  
Enthalpies Of Solution ◽  
Sulfonic Acids ◽  
13C Nuclear Magnetic Resonance ◽  
Related Compounds ◽  
C Nmr ◽  
Nuclear Magnetic

The ionization of trifluoromethane-, methane-, and benzene-sulfonic acids in Me2SO and in water has been studied by 13C nuclear magnetic resonance. While the protonation shifts of CF3SO3− and CH3SO3− in both solvents are too small to make a quantitative interpretation possible, the C6H5SO3− shift data in H2O–H2SO4 mixtures, when treated by the method of Cox and Yates, gave a pKa value of −2.5 for the ionization of C6H5SO3H. Our results are discussed in relation to those of other workers. Enthalpies of solution and of ionization of these acids and related compounds have been obtained in both solvents. Single ion enthalpies of transfer from water to Me2SO have been calculated from our data and from a transfer value for CF3SO3− (+1.9 kJ mol−1) based on the tetraphenylarsonium–tetraphenylborate extrathermodynamic assumption. The transfers are endothermic processes for the anions CH3SO3− (+29.6 kJ mol−1), C6H5SO3− (+ 20.2 kJ mol−1), and p-CH3C6H4SO3− (+ 21.8 kJ mol−1), and exothermic for H+(−27.4 kJ mol−1). These results are discussed in terms of the properties of the ions and solvents. The transfer value for H+ is a valuable measure of the basicity difference between bulk water and Me2SO. Keywords: sulfonic acids, ionization, dimethylsulfoxide, 13C NMR, calorimetry.

Nuphar thiaspirane sulfoxides. 13C nuclear magnetic resonance determined configuration and utilization in the interconversion of thiaspirane stereochemical types

1978 ◽  
Vol 56 (1) ◽  
pp. 56-61 ◽  
Author(s):  
R. T. LaLonde ◽  
C. F. Wong
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Subsequent Reduction ◽  
13C Nuclear Magnetic Resonance ◽  
Sodium Borodeuteride ◽  
C Nmr ◽  
Nuclear Magnetic

The configuration of the sulfoxide oxygen in syn- and anti-thiobinupharidine sulfoxide was determined by employing the 13C nmr sulfoxidation increments of C-6. Establishment of the 13C nmr line assignments for C-6 included the study of the C-6 and C-6′ deuterated thiobinupharidine and the corresponding sulfoxides. Thermolysis of syn-thiobinupharidine sulfoxide in DMSO and subsequent reduction with sodium borodeuteride in methanol yielded thiobinupharidine, labelled with deuterium only at C-6, and thionuphlutine B, labelled with deuterium at both C-6 and C-6′. Treatment of the anti sulfoxide in xylene or DMSO resulted in no thiobinupharidine or thionuphlutine B. Similarly, syn-neothiobinupharidine sulfoxide gave neothiobinupharidine and a new thiaspirane, thionuphlutine C. These two compounds were not produced from anti-neothiobinupharidine sulfoxide heated in xylene.

13C nuclear magnetic resonance spectra of the spirobenzylisoquinoline alkaloids and related model compounds

1977 ◽  
Vol 55 (18) ◽  
pp. 3304-3311 ◽  
Author(s):  
Donald W. Hughes ◽  
Bala C. Nalliah ◽  
Herbert L. Holland ◽  
David B. MacLean
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Isoquinoline Alkaloids ◽  
Model Compounds ◽  
Related Model ◽  
Nuclear Magnetic Resonance Spectra ◽  
13C Nuclear Magnetic Resonance ◽  
C Nmr ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The natural abundance 13C nuclear magnetic resonance spectra of a number of spirobenzylisoquinoline alkaloids and related model compounds have been recorded. The carbon resonances of the alkaloids were assigned by comparison with the spectra of other isoquinoline alkaloids and with those of the model compounds. It has been shown that 13C nmr spectroscopy may be used to differentiate between diastereomers in this series.

15N and 13C nuclear magnetic resonance of deoxydinucleotide monophosphates. II. Protonation of the homo dimers deoxycytidylyl-(3′,5′)-deoxycytidine, thymidylyl-(3′,5′)-thymidine, and deoxyadenylyl-(3′,5′)-deoxyadenosine in dimethyl sulfoxide

1990 ◽  
Vol 68 (11) ◽  
pp. 2033-2038 ◽  
Author(s):  
Giovanna Barbarella ◽  
Massimo Luigi Capobianco ◽  
Luisa Tondelli ◽  
Vitaliano Tugnoli
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Dimethyl Sulfoxide ◽  
Phosphate Group ◽  
Nmr Data ◽  
13C Nuclear Magnetic Resonance ◽  
C Nmr ◽  
Nuclear Magnetic

The preferential protonation sites of the homo dimers deoxycytidylyl-(3′,5′)-deoxycytidine, thymidylyl-(3′,5′)-thymidine, and deoxyadenylyl-(3′,5′)-deoxyadenosine were established by nitrogen-15 and carbon-13 NMR in dimethyl sulfoxide, in the presence of varying amounts of CF3COOH. The nitrogen-15 NMR data show that in d(CpC) the capability of the two N3 nitrogens to accept the proton is slightly different. In d(TpT) and d(ApA) the protonation of the phosphate group leads to significant variations of the chemical shift of the carbons adjacent to phosphorus. Keywords: deoxydinucleotides, protonation, 15N and 13C NMR.

13C nuclear magnetic resonance studies. 58. 13C spectra of a variety of bicyclo[2.2.2]octane derivatives. Further definition of the deshielding δ effect

1976 ◽  
Vol 54 (6) ◽  
pp. 917-925 ◽  
Author(s):  
J. B. Stothers ◽  
C. T. Tan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
Definition Of ◽  
C Nmr ◽  
Nuclear Magnetic

The 13C nmr spectra of 35 bicyclo[2.2.2]octane and -octene derivatives have been determined to extend our examinations of the effects of stereochemistry on the shieldings of closely neighboring carbons. This series includes a variety of methyl substituted bicyclooctanols and -octenols as well as the corresponding hydrocarbons and some bicyclooctanones. With the bicyclo[2.2.2]octane skeleton it is possible to examine an array of systems having substituents separated by three and four bonds in a variety of orientations. The interactions, termed γ and δ effects, respectively, produce distinctive shielding variations which are useful for stereochemical elucidations. Particularly interesting are the pronounced shifts observed for the carbons bearing closely neighboring substituents. Characteristically, for vicinal substituents, these carbons are shielded while for syn-axial δ interactions, these carbons are deshielded by as much as 8.6 ppm. The results are compared with the trends found in other sterically crowded Systems.

Microbial hydroxylation of steroids. 7. Hydroxylation of B-nortestosterone and related compounds by Rhizopus arrhizus ATCC 11145, and 13C nuclear magnetic resonance spectra of some B-norsteroids

1981 ◽  
Vol 59 (11) ◽  
pp. 1651-1655 ◽  
Author(s):  
Herbert L. Holland
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Rhizopus Arrhizus ◽  
Nuclear Magnetic Resonance Spectra ◽  
13C Nuclear Magnetic Resonance ◽  
Mechanism Of Oxidation ◽  
Related Compounds ◽  
Stereoelectronic Interactions ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The incubation of B-norandrost-4-ene-3-ones and B-nor-3β-hydroxyandrost-5-enes with Rhizopus arrhizus ATCC 11145 has been described. The products are consistent with a mechanism of oxidation at C-6 in which the stereochemistry of substitution at C-6 is controlled by stereoelectronic interactions in the substrate, and is not dictated by enzymic constraint during the reaction. The carbon-13 nuclear magnetic resonance spectra of several B-nor-Δ4 and Δ5 steroids have been presented.

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