PROTONATION OF THE AMIDE GROUP: I. THE BASICITIES OF SUBSTITUTED BENZAMIDES

1960 ◽  
Vol 38 (9) ◽  
pp. 1518-1525 ◽  
Author(s):  
J. T. Edward ◽  
H. S. Chang ◽  
K. Yates ◽  
Ross Stewart
Keyword(s):  
Sulphuric Acid ◽  
Spectrophotometric Method ◽  
Amide Group ◽  
Benzoic Acids ◽  
Acid Media ◽  
Group I ◽  
Substituted Benzamides ◽  
Hammett Σ Constants

The basicities of benzamide and of 11 meta- and para-substituted benzamides in sulphuric acid media have been determined by a spectrophotometric method. The [Formula: see text] values of the protonated benzamides were found to be proportional to the Hammett σ constants for the substituents, unlike the [Formula: see text] values of the protonated benzaldehydes, acetophenones, and benzoic acids, which are approximately proportional to σ+ constants. The lack of conjugation between the protonated amide group and the ring, which is indicated by these results, is most easily interpreted in terms of N-protonation although O-protonation cannot be completely excluded. Various other aspects of the problem of N- versus O-protonation are also discussed.

PROTONATION OF THE CARBONYL GROUP: II. THE BASICITIES OF SUBSTITUTED BENZALDEHYDES

1959 ◽  
Vol 37 (4) ◽  
pp. 664-671 ◽  
Author(s):  
K. Yates ◽  
Ross Stewart
Keyword(s):  
Sulphuric Acid ◽  
Carbonyl Group ◽  
Spectrophotometric Method ◽  
Ultraviolet Absorption ◽  
Steric Effects ◽  
Acid Media ◽  
Substituted Benzaldehydes ◽  
Group Ii

The basicities of seven meta- and para-substituted benzaldehydes have been determined by a spectrophotometric method in sulphuric acid media. The simple Hammett relation does not hold for these bases but a good correlation exists between [Formula: see text] and σ+. The effects of substitution on the wavelengths of maximal ultraviolet absorption in benzaldehyde are compared with those in acetophenone.The basicity of o-tolualdehyde was determined in an attempt to estimate the steric effects of ortho substitution. The effects of symmetrical trisubstitution on the basicity of benzaldehyde and acetophenone are compared and discussed.

scholarly journals Spectrophotometric investigation of the Fe(III)-disulphonate hydroquinone complex

2005 ◽  
Vol 70 (4) ◽  
pp. 651-659
Author(s):  
Mirjana Obradovic ◽  
Snezana Mitic ◽  
Snezana Tosic ◽  
A.N. Pavlovic
Keyword(s):  
Stability Constant ◽  
Spectrophotometric Method ◽  
Calibration Curve ◽  
Relative Stability ◽  
Time Stability ◽  
Acid Media ◽  
Influence Of Temperature ◽  
Complex Dependence ◽  
Indigo Blue

Iron(III) form an indigo-blue complex with the disulphonated product of hydroquinone (K2S2Hy) in acid media with an absorption maxima at 600 nm. The time stability of the complex, dependence of the complex absorbance on pH and the influence of temperature and solvent were followed on the basis of spectrophotometric measurements. Using the Job, mole ratio and Henry?Franck?Ostwald methods, the composition and relative stability constant of this complex, in 80 vol.% ethanol as solvent, were determined (1:1;log??293 = 3.37). A new spectrophotometric method for the determination of iron has been developed and the calibration curve is linear in the concentration range from0.65 to 6.45 ?g cm-3. The effects of foreign ions on the determination of iron were investigated in order to assess the selectivity of the method. The method was applied for the determination of Fe(III) in the natural juice of beet.

Mechanism of reactions of some N 1-substituted biguanides with chromium(VI) in aqueous sulphuric acid media

1988 ◽  
pp. 1557 ◽  
Author(s):  
Rupendranath Banerjee ◽  
Anamika Bhattacharya ◽  
Prabir K. Das ◽  
Amiya K. Chakraburtty
Keyword(s):  
Sulphuric Acid ◽  
Acid Media ◽  
Chromium Vi
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