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.

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.

Steric Effects on the Near-Ultraviolet Absorption (Soret Band) of Porphyrins

1963 ◽  
Vol 85 (22) ◽  
pp. 3621-3624 ◽  
Author(s):  
Alsoph H. Corwin ◽  
David G. Whitten ◽  
Earl W. Baker ◽  
George G. Kleinspehn
Keyword(s):  
Soret Band ◽  
Ultraviolet Absorption ◽  
Steric Effects ◽  
Near Ultraviolet

The electrochemical behaviour of chromium plates in sulphuric acid media in the presence of selenite ions

1983 ◽  
Vol 18 (3) ◽  
pp. 209-216 ◽  
Author(s):  
St. Rashkov ◽  
M. Monev ◽  
G. Raichevski
Keyword(s):  
Sulphuric Acid ◽  
Electrochemical Behaviour ◽  
Acid Media

IONIZATION OF ORGANIC COMPOUNDS: III. BASICITIES OF PROPIONIC ACID AND PROPIONAMIDE

1962 ◽  
Vol 40 (5) ◽  
pp. 966-975 ◽  
Author(s):  
J. T. Edward ◽  
I. C. Wang
Keyword(s):  
Sulphuric Acid ◽  
Propionic Acid ◽  
Organic Compounds ◽  
Acid Concentration ◽  
Ultraviolet Absorption ◽  
Protonation Constants ◽  
Acidity Function ◽  
Hammett Acidity Function ◽  
Ionization Ratio

Protonation constants (pKBH+) of −6.8 and −0.9 have been determined for propionic acid and propionamide, respectively, from measurements of their ultraviolet absorption in various concentrations of sulphuric acid. The ionization ratio of propionamide and of other amides increases more slowly than the Hammett acidity function, h0, with increase in acid concentration. This may be explained by assuming that in a given concentration of sulphuric acid the protonated amide is more heavily hydrated than the protonated Hammett indicator used to establish the h0 scale for this region of acid concentrations.

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.

scholarly journals The Photochemical Reactivity of Some Benzoylthiophenes. III. The Effect of an Adjacent Methyl Group on the Excited State Reactivity of 2-Benzoylthiophene

1975 ◽  
Vol 53 (1) ◽  
pp. 1-11 ◽  
Author(s):  
D. R. Arnold ◽  
B. M. Clarke Jr.
Keyword(s):  
Excited State ◽  
Carbonyl Group ◽  
Emission Spectra ◽  
Ultraviolet Absorption ◽  
Photochemical Reactivity ◽  
Methyl Group ◽  
Partial Energy ◽  
Phosphorescence Emission ◽  
Π State

The ultraviolet absorption and phosphorescence emission spectra of 2-(2-methylbenzoyl) thiophene (1), 2-benzoyl-3-methylthiophene (2), 2-benzoyl-4-methylthiophene (3), and 2-benzoyl-5-methylthiophene (4) are reported and analyzed. Partial energy diagrams are constructed. The lowest triplet is assigned as a π,π* state of the 2-thienoyl chromophore in every case. Photocycloaddition of isobutylene to the carbonyl group was observed with 1 and 2. The oxetanes are thermally unstable; olefins 1-(2-thienyl)-1-(2-methylphenyl)-2-methylpropene (from 1) and 1-phenyl-1-(2-(3-methylthienyl))-2-methylpropene (from 2) were formed and characterized. Irradiation of 1 and 2 in O-deuteromethanol did not lead to incorporation of deuterium; no reaction was observed. These results are discussed in terms of the existing generalizations potentially useful for predicting photochemical reactivity.

scholarly journals New aminothiazolylglycylcephalosporins with a 1,5-dihydroxy-4-pyridone-2-carbonyl group. II. Synthesis and antibacterial activity of MT0703 and its diastereomers.

1990 ◽  
Vol 43 (2) ◽  
pp. 189-198 ◽  
Author(s):  
HIROKO OGINO ◽  
KATSUYOSHI IWAMATSU ◽  
KIYOAKI KATANO ◽  
SATORU NAKABAYASHI ◽  
TAKASHI YOSHIDA ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Carbonyl Group ◽  
Group Ii

Reaction of galena in ferric sulphate—sulphuric acid media

1994 ◽  
pp. 125-138 ◽  
Author(s):  
J. E. Dutrizac ◽  
T. T. Chen
Keyword(s):  
Sulphuric Acid ◽  
Ferric Sulphate ◽  
Acid Media

Studies of the Wallach Transformation. II. Steric Effects in Some Symmetrically Disubstituted Azoxybenzenes

1951 ◽  
Vol 4 (2) ◽  
pp. 185
Author(s):  
PH Gore ◽  
GK Hughes
Keyword(s):  
Sulphuric Acid ◽  
Important Influence ◽  
Steric Effects ◽  
Hydroxyl Group ◽  
Azoxy Compounds ◽  
Point Of Entry ◽  
Substituent Group

Study of the behaviour of symmetrical azoxy compounds in the Wallach Transformation shows the important influence of size of a substituent group ortho to the point of entry of the hydroxyl group.�The various processes known to occur in a solution of azoxybenzene in sulphuric acid are discussed.

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