ULTRAVIOLET ABSORPTION SPECTRA OF ARYL SUBSTITUTED UREAS

1953 ◽  
Vol 31 (10) ◽  
pp. 896-908 ◽  
Author(s):  
J. P. Picard ◽  
A. F. McKay
Keyword(s):  
Absorption Band ◽  
Absorption Spectra ◽  
Inductive Effect ◽  
Progressive Increase ◽  
Ultraviolet Absorption

Absorption spectra of a number of substituted aryl-and sym-diarylureas have been determined in ethanol. As conjugation in the chromophores increased, a gradual displacement of the maxima of the conjugative absorption band towards the visible occurred. This displacement was accompanied by a progressive increase in intensity of absorption. The effect on the absorption spectra of replacing hydrogen of the aryl substituents by alkoxy, methyl, or halogeno groups is discussed. A relationship between the inductive effect of these groups and their influence on the absorption spectra is indicated.

SPECTROSCOPIC STUDIES OF KETO–ENOL EQUILIBRIA: PART 2. ANOMALOUS ULTRAVIOLET ABSORPTION SPECTRA OF SATURATED 1,2-DICYANO ESTERS

1962 ◽  
Vol 40 (12) ◽  
pp. 2272-2277 ◽  
Author(s):  
T. R. Kasturi ◽  
B. N. Mylari ◽  
A. Balasubramanian ◽  
C. N. R. Rao
Keyword(s):  
Absorption Band ◽  
Absorption Spectra ◽  
Spectroscopic Studies ◽  
Anomalous Behavior ◽  
Enol Form ◽  
Ultraviolet Absorption ◽  
Polar Solvents ◽  
Solvent Dependence

1,2-Dicyano esters show an absorption band around 245 mμ in alcoholic solutions which is not found in non-polar and other polar solvents. This anomalous behavior has been found to be due to the unusual solvent dependence of the equilibrium between the keto and enol forms. The intensity of the absorption band in alcoholic solutions decreases with increase in concentration of the 1,2-dicyano ester, indicating association of the enol form. The keto–enol equilibrium is also found to be sensitive to the substituent R of the alcohol ROH.

Coordination complexes of amino acids: Preparation and properties of some Amino-acidatobis(acetylacetonato)cobalt(III) and Bis(amino-acidato)(acetylacetonato)cobalt(III) complexes

1968 ◽  
Vol 21 (3) ◽  
pp. 679 ◽  
Author(s):  
SH Laurie
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Absorption Band ◽  
Absorption Spectra ◽  
Coordination Complexes ◽  
Optically Active ◽  
Ultraviolet Absorption ◽  
Visible Absorption ◽  
Molecular Weights ◽  
Cotton Effects

Complexes of the type [Co(acac)2(aa)] have been synthesized, in which the amino acid is DL- and L-phenylalanine, L-valine, L-leucine, L-proline, DL-, L-,and D-alanine, and glycine. The complexes were characterized by means of analyses, molecular weights, and their infrared, visible, and ultraviolet absorption spectra. During the syntheses several of the bis(amino-acidato) complexes, [Co(acac)(aa)2], were also formed; the L-phenylalanine and glycine complexes were isolated and characterized. The complexes prepared from the optically active amino acids exhibited Cotton effects in the region of the visible absorption band (lA1g, + 1T1g). These effects have been attributed to induced asymmetry rather than stereoselectivity. Amino acids of the same configuration gave rise to Cotton effects of the same sign, ie. (-)590-[Co(acac)2(L-aa)], (-)6590-[Co(acac)(L-aa)2], and (+)590-[Co(acac),(D-aa)].

FAR ULTRAVIOLET ABSORPTION SPECTRA OF N3AND N2+GENERATED BY ELECTRONS IMPACTING GASEOUS N2

2013 ◽  
Vol 779 (1) ◽  
pp. 40 ◽  
Author(s):  
Yu-Jong Wu ◽  
Hui-Fen Chen ◽  
Shiang-Jiun Chuang ◽  
Tzu-Ping Huang
Keyword(s):  
Absorption Spectra ◽  
Ultraviolet Absorption ◽  
Far Ultraviolet

scholarly journals ULTRAVIOLET ABSORPTION SPECTRA AT REDUCED TEMPERATURES

1950 ◽  
Vol 187 (1) ◽  
pp. 299-312
Author(s):  
R.L. Sinsheimer ◽  
J.F. Scott ◽  
J.R. Loofbourow
Keyword(s):  
Absorption Spectra ◽  
Ultraviolet Absorption

ULTRAVIOLET ABSORPTION SPECTRA AND ACIDITIES OF ISOMERIC THIATRIAZOLE AND TETRAZOLE DERIVATIVES

1959 ◽  
Vol 37 (3) ◽  
pp. 563-574 ◽  
Author(s):  
Eugene Lieber ◽  
J. Ramachandran ◽  
C. N. R. Rao ◽  
C. N. Pillai
Keyword(s):  
Absorption Spectra ◽  
Absorption Maximum ◽  
Dipole Moments ◽  
Ring System ◽  
Ultraviolet Absorption ◽  
Characteristic Absorption ◽  
Tetrazole Derivatives

The ultraviolet absorption spectra of 5-(substituted)amino-1,2,3,4-thiatriazoles and the corresponding isomeric 1-substituted-tetrazoline-5-thiones have been studied. The spectra and the dipole moments of the 5-(substituted)amino-1,2,3,4-thiatriazoles eliminate the possibility of meso-ionic structures for these compounds. The dipole moments of 5-amino-, 5-methylamino-, and 5-dimethylamino-1,2,3,4-thiatriazole were all high but approximately of the same value (5.77 to 5.84 D). This suggests that the amino thiatriazoles are best represented by conventional covalent structures with significant ionic resonance contributions. The thiatriazole ring system exhibits a characteristic absorption maximum at 250–255 mμ and an electron-withdrawing effect approximately equal to the tetrazolyl ring system. The tetrazolinethionolyl ring system is similarly electron-withdrawing. The relative acidities of the 1-substituted-tetrazoline-5-thiones and the 5-alkylmercaptotetrazoles have also been studied and the results support the observations made on the basis of their ultraviolet absorption spectra.

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