Low Temperature Infrared Study of Hydrogen Bonding in Dissolved Pyrrole and Indole

1973 ◽  
Vol 51 (7) ◽  
pp. 1075-1082 ◽  
Author(s):  
Marie-Claude Bernard-Houplain ◽  
C. Sandorfy
Keyword(s):  
Hydrogen Bonding ◽  
Low Temperature ◽  
Spectroscopic Methods ◽  
Infrared Study ◽  
Stretching Vibration ◽  
Self Association ◽  
Associated Species

Self-association by hydrogen bonding in the case ot pyrrole was studied by i.r. spectroscopic methods. The fundamental first and second overtones of the NH stretching vibration were measured at different concentrations and at temperatures ranging from 22 to −190 °C. The existence of at least two associated species in solution has been ascertained. 2,5-Dimethylpyrrole and indole were also studied and gave similar results.

A Low Temperature Infrared Study of Self-association in Thiols

1972 ◽  
Vol 50 (22) ◽  
pp. 3594-3600 ◽  
Author(s):  
R. Bicca de Alencastro ◽  
C. Sandorfy
Keyword(s):  
Hydrogen Bonding ◽  
Low Temperature ◽  
Infrared Spectra ◽  
Low Temperatures ◽  
Infrared Study ◽  
Text Type ◽  
Stretching Vibration ◽  
Aliphatic Thiols ◽  
Self Association ◽  
Associated Species

The infrared spectra of several aliphatic thiols and of benzenethiol were measured between 2400 and 2700 cm−1, and 4800 and 5300 cm−1 in a 1:1 mixture of CCl3F and C2F4Br2, at temperatures ranging from 20 to −190 °C. Dimerization takes place at low temperatures and more highly associated species also appear. Free S—H groups are present in the solutions as well as in the pure liquids, even at the lowest temperatures. The association is of the [Formula: see text] type in aliphatic thiols; both [Formula: see text] and [Formula: see text] bonds are found in the case of benzenethiol and α-toluenethiol. Hydrogen bonding has little effect on the anharmonicity of the S—H stretching vibration.

A Low-temperature Infrared Study of Self-association in Thiolic Acids

1973 ◽  
Vol 51 (9) ◽  
pp. 1443-1447 ◽  
Author(s):  
R. Bicca de Alencastro ◽  
C. Sandorfy
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Carbonyl Groups ◽  
Infrared Study ◽  
Text Type ◽  
Stretching Vibration ◽  
Self Association ◽  
High Concentrations ◽  
Associated Species ◽  
Anharmonicity Constants

The i.r. spectra of thioloacetic and thiolobenzoic acids were measured in both the fundamental and first overtone regions of the S—H stretching vibration, in a mixture of CCl3F and C2F4Br2, at temperatures ranging from 20 to −190 °C. [Formula: see text] type bonds are formed at low temperatures or at high concentrations of solute. Two different species can be detected. The first is probably an open dimer and the second a cyclic dimer. The S—H anharmonicity constants are of the order of 50–60 cm−1, for both free and associated species, and have about the same value as in aliphatic or aromatic mercaptans. Carbonyl groups have lower anharmonicities. Their value is about 10 cm−1, for both free and associated species.

A Low Temperature Infrared Study of Hydrogen Bonding in N-Alkylacetamides

1973 ◽  
Vol 51 (21) ◽  
pp. 3640-3646 ◽  
Author(s):  
Marie-Claude Bernard-Houplain ◽  
C. Sandorfy
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Low Temperature ◽  
Infrared Spectra ◽  
Bond Formation ◽  
Coupling Constant ◽  
Infrared Study ◽  
Hydrogen Bond Formation ◽  
Stretching Vibration ◽  
Secondary Amides

The infrared spectra of N-methylacetamide and two other secondary amides were measured in solution at temperatures ranging from 22 to −190 °C in both the fundamental and the overtone regions. At least two hydrogen bonded species are found as association increases with decreasing temperature. The effect of hydrogen bond formation on the anharmonicity of the NH stretching vibration and on the NH stretching – NH bending coupling constant is examined.

A Low Temperature Infrared Study on the Association of Thiols with Pyridine and Triethylamine

1973 ◽  
Vol 51 (7) ◽  
pp. 985-990 ◽  
Author(s):  
R. Bicca De Alencastro ◽  
C. Sandorfy
Keyword(s):  
Low Temperatures ◽  
Bond Formation ◽  
Infrared Study ◽  
Hydrogen Bond Formation ◽  
Text Type ◽  
Predominant Species ◽  
Type Complex ◽  
Proton Donors ◽  
Stretching Vibration ◽  
Associated Species

The infrared spectra of solutions containing propane-1-thiol or benzenethiol as proton donors, and pyridine or triethylamine as proton acceptors were measured down to about −100 °C. The dependence of hydrogen bond formation on concentration and temperature was studied at the fundamental and overtone region of the S—H stretching vibration. The predominant species is found to be a 1:1 [Formula: see text] type complex. In addition, evidence was found for the existence of more highly associated species at low temperatures. Thiol–thiol [Formula: see text] type hydrogen bonds are also present in the case of benzenethiol–pyridine mixtures.

Low Temperature Infrared Study of Hydrogen Bonding in Acetone Oxime-d6

1973 ◽  
Vol 51 (9) ◽  
pp. 1441-1442 ◽  
Author(s):  
Thérèse Di Paolo ◽  
Camille Sandorfy
Keyword(s):  
Hydrogen Bonding ◽  
Low Temperature ◽  
Infrared Spectrum ◽  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Infrared Study ◽  
Acetone Oxime

The infrared spectrum of (CD3)2C=N—OH was measured in solution down to liquid nitrogen temperature. As the temperature is lowered several new "associated bands" appear indicating the presence of species more highly associated than cyclic dimers or trimers.

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