Competitive inclusion of chloro-substituted acetic acids into β-cyclodextrin monitored by rotational correlation frequencies of 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxy radical

1982 ◽  
Vol 60 (15) ◽  
pp. 1959-1961 ◽  
Author(s):  
Yoshiaki Motozato ◽  
Tsukasa Nishihara ◽  
Chuichi Hirayama ◽  
Yoshiaki Furuya ◽  
Yoshio Kosugi
Keyword(s):  
Acetic Acid ◽  
Structural Change ◽  
Temperature Dependence ◽  
Trichloroacetic Acid ◽  
Esr Spectroscopy ◽  
Esr Spectra ◽  
Nmr Studies ◽  
Acetic Acids ◽  
Rotational Correlation

Competitive inclusion in β-cyclodextrin between 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxy and chloro-substituted acetic acids has been monitored by esr spectroscopy. The temperature dependence of the rotational correlation frequencies calculated by Kivelson's equation, using esr spectra of the radical, suggests that a structural change of β-cyclodextrin occurs at about 30 °C and that trichloroacetic acid is included extensively at 20–35 °C, but significant inclusion of acetic acid is not observed. The degree of competitive inclusion is in the order of trichloro, dichloro, and monochloroacetic acids over the range of 20–80 °C. Carbon-13 nmr studies also prove the inclusion of trichloroacetic acid showing an inclusion shift of the trichloromethyl carbon by 1.4 ppm.

Solution Coordination Chemistry of Protohaemin IX Peptide Derivatives

1999 ◽  
Vol 03 (08) ◽  
pp. 691-702
Author(s):  
ELENA A. ROZHKOVA ◽  
RIMA P. EVSTIGNEEVA ◽  
VICTOR N. NEMYKIN
Keyword(s):  
Acetic Acid ◽  
High Spin ◽  
Trichloroacetic Acid ◽  
Esr Spectroscopy ◽  
Strong Field ◽  
Electronic Spectroscopy ◽  
Weak Field ◽  
Sodium Cyanide ◽  
Peptide Fragments ◽  
Peptide Derivatives

As part of an investigation aimed at developing artificial models for mimicking haemoprotein activity, four C-aminoacyl protohaemin IX derivatives with one or two -L-Leu-L- HisOMe (complexes 3 and 1) or -β-Ala-L- HisOMe (complexes 4 and 2) peptide fragments have been studied by means of electronic and ESR spectroscopy. The bis-His complexes 1 and 2 are predominantly low-spin ( S = 1/2) species, while the mono-His complexes 3 and 4 are predominantly high-spin ( S = 5/2) species. Products of the treatment of starting complexes 1–4 with trichloroacetic acid, acetic acid, methylimidazole, sodium cyanide and sodium hydroxide have been analysed by electronic spectroscopy. Weak-field ligands lead to predominantly high-spin hexacoordinated complexes, while strong-field ligands result in predominantly low-spin ones.

Electrochemical behaviour and ESR spectra of nitro substituted mono- and dibenzoylmethylenebenzthiazolines and selenazolines

1979 ◽  
Vol 44 (5) ◽  
pp. 1540-1551 ◽  
Author(s):  
Jaro Komenda ◽  
Jiří Huzlík
Keyword(s):  
Electron Transfer ◽  
Esr Spectroscopy ◽  
Electrochemical Behaviour ◽  
Spectroscopic Studies ◽  
Esr Spectra ◽  
Slow Electron

Compounds of the type of 2-(4'-nitrobenzoyl)methylene-3-ethylbenzothiazoline (I) and 2-bis-(p-nitrobenzoyl)methylene-3-ethylbenzothiazoline (II) were studied polarographically and by ESR spectroscopy to obtain informations about their electrochemical and follow-up reactions and their conformation. Whereas with compounds of the type I the conjugation in their molecules is preserved, with type II the coplanarity of the molecules is disturbed, which is manifested in the values of the splitting constants of the ESR spectra and a slow electron transfer between both nitrophenyl substituents. These conclusions are supported by NMR spectroscopic studies.

Association of radical anion with alkali cations. IV. ESR study of the 4-nitrobenzophenone radical anion

1980 ◽  
Vol 45 (2) ◽  
pp. 369-375 ◽  
Author(s):  
Stanislav Miertuš ◽  
Ondrej Kyseľ
Keyword(s):  
Hyperfine Splitting ◽  
Radical Anion ◽  
Esr Spectroscopy ◽  
Supporting Electrolyte ◽  
Esr Spectra ◽  
Proton Donor ◽  
Alkali Cations

The 4-nitrobenzophenone radical anion prepared by electrolysis was studied by ESR spectroscopy. On the basis of the interpretation of ESR spectra, the conformation of this system was estimated. The effect of the concentration of supporting electrolyte and of the presence of a proton-donor agent (C2H5OH) was examined. It is assumed that changes in hyperfine splitting constants are caused by association.

35Cl NQR Spectroscopy on Salts and Molecular Compounds of Trichloroacetic Acid

1986 ◽  
Vol 41 (1-2) ◽  
pp. 215-224 ◽  
Author(s):  
Winfried Fichtner ◽  
Axel Markworth ◽  
Norbert Weiden ◽  
Alarich Weiss
Keyword(s):  
Frequency Shift ◽  
Temperature Dependence ◽  
Linear Relation ◽  
Trichloroacetic Acid ◽  
Mean Frequency ◽  
35Cl Nqr ◽  
The Mean ◽  
Molecular Compounds

The temperature dependence of salts M(1)H(Cl3CCOO)2 and molecular compounds of trichloroacetic acid with amines and benzaldehydes, TCA · X, was studied,The data fit rather well to the known dependence of the mean frequency shift Δ <v(35Cl)> on the pkadifference of X with respect to TCA. A linear relation is observed between the bleaching out temperature Tb of the 35Cl NQR lines and Δ <v(35Cl)> for M(1)H(Cl3CCOO)2 and for TCA · X, X = benzaldehydes.

scholarly journals Computational notes on the electronic properties of carboxylic acid

2020 ◽  
Vol 9 (2) ◽  
pp. 1079-1082
Keyword(s):  
Acetic Acid ◽  
Carboxylic Acid ◽  
Electronic Properties ◽  
Carboxylic Acids ◽  
Normal Mode ◽  
Normal Modes ◽  
Carboxyl Groups ◽  
Vibrational Characteristics ◽  
Vibrational Features ◽  
Acetic Acids

The present work describing the electronic properties and vibrational characteristics of carboxylic acids. Acetic acid is chosen as model molecules then optimized at B3LYP/6-31g(d,p) level of theory. The vibrational frequencies were calculated at the same level of theory. Band assignments which were calculated as 18 normal modes were assigned as one compare the normal mode coordinates with original one. Band assignments were described indicating the directions of normal modes in terms the vibrating atoms of the acetic acids. It could be concluded that DFT could be a useful tool for elucidation both the structural and vibrational features of carboxylic acids and then further utilized for assignment of the structures contains carboxyl groups which are known as most reactive structures in chemistry, biology and environment.

scholarly journals SYNTHESIS OF ESTERS OF HALOGENOACETIC ACIDS

2020 ◽  
Vol 2020 (3) ◽  
pp. 38-43
Keyword(s):  
Acetic Acid ◽  
Acid Catalyst ◽  
Primary Amines ◽  
Primary Alcohols ◽  
Sulfuric Acid Catalyst ◽  
Nucleophilic Exchange ◽  
Pmr Spectra ◽  
High Yields ◽  
Esterification Reactions ◽  
Acetic Acids

Amidoalkylating reagents containing a phthalimide group are used in the synthesis of hard-to-reach primary amines and complex heterocyclic compounds. These types of amidoalkylating compounds are suitable reagents for nucleophilic substituted reactions in acidic media due to their resistance to acids. Result of reactions of amidoalkylating reagents-N-hydroxyethylphthalimide and N-hydroxymethylphthalimide with aliphatic carbonic acids can also produce new bactericidal and fungicidal esters. In this study, halogen acids reacted with N-hydroxymethylphthalimide monochloric acetic acid, monobromic acetic acid, monoiodic acetic acid, trifluoric acetic acid and trichloroacetic acid, as well as, N-b-hydroxyethylphthaleidyl monohydric acid. As a result of the reactions, new phthalimidomethyl and phthalimidoethyl esters of haloacetic acids were synthesized. The physical properties of crystalline esters have been determined. The structure of these compounds were confirmed by the analysis of their IR and PMR spectra. The esterification reactions of halogenated acetic acids were carried out in a benzene solvent and a sulfuric acid catalyst with primary alcohols, N-hydroxymethylphthalimide and N-β- beta hydroxyethylphthalimide,. It was found that in a benzene solvent, which increases the rate of bimolecular nucleophilic exchange in primary alcohols, phthalimidoethyl esters of halogen acid are formed in high yields, and phthalimidomethyl esters are formed in low yields. It was shown that the reaction of esterification of halogen acids with N-hydroxymethylphthalimide proceeds with monomolecular nucleophilic exchange.

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