THE INFRARED FREQUENCIES AND INTENSITIES OF THE HYDROXYL BAND IN ORTHO-SUBSTITUTED PHENOLS

1961 ◽  
Vol 39 (3) ◽  
pp. 471-480 ◽  
Author(s):  
K. U. Ingold ◽  
D. R. Taylor
Keyword(s):  
Alkyl Substituent ◽  
Hydroxyl Group ◽  
Cis And Trans Isomers ◽  
Stretching Vibration ◽  
Alkyl Phenols ◽  
The Difference ◽  
Ortho Cresol ◽  
Infrared Frequencies ◽  
Cis And Trans ◽  
Hydroxyl Band

The infrared frequencies, intensities, and half-band widths of the fundamental stretching vibration of the hydroxyl group have been measured for a large number of ortho-alkyl phenols. It has been found that phenols containing a single ortho-alkyl substituent exist as cis and trans isomers in unequal amounts, the trans isomer being the more abundant. The difference in free energy between the two isomers in dilute solution in carbon tetrachloride at 24 °C has been measured for ortho-cresol, 2,3-dimethyl phenol, and several ortho-tert-alkyl phenols.

THE INFRARED FREQUENCIES AND INTENSITIES OF THE HYDROXYL BAND OF ORTHO-ALKYL PHENOLS IN THE VAPOR PHASE

1962 ◽  
Vol 40 (1) ◽  
pp. 111-121 ◽  
Author(s):  
K. U. Ingold
Keyword(s):  
Vapor Phase ◽  
Hydroxyl Group ◽  
Trans Isomers ◽  
Polar Solvents ◽  
Cis And Trans Isomers ◽  
Stretching Vibration ◽  
Alkyl Phenols ◽  
Infrared Frequencies ◽  
Cis And Trans ◽  
Hydroxyl Band

The infrared frequencies and intensities of the fundamental stretching vibration of the hydroxyl group have been measured for a number of ortho-alkyl phenols in the vapor phase over a range of temperatures. Both quantities have been shown to depend on internal steric and environmental factors. The differences in enthalpy between the cis and trans isomers of several 2-tert-alkyl phenols have been measured, and it is concluded that the latter are not significantly stabilized relative to the former by solvation in non-polar solvents.

THE EFFECT OF SOLVENT AND TEMPERATURE ON THE CIS–TRANS ISOMERISM OF ORTHO-tert-ALKYL PHENOLS

1961 ◽  
Vol 39 (3) ◽  
pp. 481-487 ◽  
Author(s):  
K. U. Ingold ◽  
D. R. Taylor
Keyword(s):  
Trans Isomers ◽  
Infrared Band ◽  
Effect Of Solvent ◽  
Cis And Trans Isomers ◽  
Stretching Vibration ◽  
Alkyl Phenols ◽  
Enthalpy And Entropy ◽  
Cis And Trans

The effects of different solvents and of a change of temperature on the infrared band due to the fundamental hydroxyl stretching vibration in several 2,6-di-t-alkyl phenols and in the corresponding ortho-t-alkyl phenols have been examined. The conclusion that the two bands observed in ortho-t-alkyl phenols represent cis and trans isomers has been confirmed. The differences in enthalpy and entropy between the two isomers have been measured for six different phenols.

Reactivities of Piperazine-2,5-diones in Radical Bromination Reactions

1996 ◽  
Vol 49 (11) ◽  
pp. 1229 ◽  
Author(s):  
CLL Chai ◽  
DCR Hockless ◽  
AR King
Keyword(s):  
Crystal Structure ◽  
Amino Acid ◽  
Chemical Reactivity ◽  
Trans Isomers ◽  
Radical Bromination ◽  
Conformational Effects ◽  
Cis And Trans Isomers ◽  
The Difference ◽  
Cis And Trans

The reactivities of various N,N'- diacetylated piperazine-2,5-diones towards radical bromination reactions are reported. The studies show that glycyl centres of piperazine-2,5-diones are more reactive towards radical bromination reactions compared to α-substituted amino acid centres. In addition, large differences in reactivities were observed for the cis and trans isomers of N,N'-diacetylated alanine anhydride. Single-crystal structure determination of each isomer revealed that conformational effects may account for the difference in chemical reactivity.

Synthesis of the cis and trans isomers of 4-Chloro-L-proline, 4-Bromo-L-proline, and 4-Amino-L-proline

1967 ◽  
Vol 20 (7) ◽  
pp. 1493 ◽  
Author(s):  
RH Andreatta ◽  
V Nair ◽  
AV Robertson ◽  
WRJ Simpson
Keyword(s):  
Methyl Ester ◽  
Sodium Borohydride ◽  
Protecting Groups ◽  
Hydroxyl Group ◽  
Side Reactions ◽  
Trans Isomers ◽  
Azide Ion ◽  
Cis And Trans Isomers ◽  
Proline Derivatives ◽  
Cis And Trans

cis- and trans-4-Chloro- and 4-bromo-L-prolines have been synthesized stereospecifically, the key step being SN2 displacement of a free or substituted 4-hydroxyl group in suitably protected 4-hydroxy-L- prolines. Similar displacements with azide ion followed by reduction provide convenient routes to cis- and trans- 4-amino-L-proline. A less satisfactory pathway to cis-4-aminoproline is reduction of a 4- oximinoproline derivative. In the course of the syntheses, which involve a variety of protecting groups, 45 new L-proline derivatives have been prepared. Unexpected side reactions were the formation of cis-4-hydroxyprolinamide by the action of ammonia on trans-4- bromoproline, and the reduction by sodium borohydride of N- benzyloxycarbonyl-4-oximinoproline methyl ester to N-benzyloxycar- bonyl-4-oximinoprolinol.

PREPARATION AND STEREOCHEMISTRY OF 1,2-O-(2′-HYDRO0XY-ETHYLIDENE)- AND 1,2-O-(HYDROXYISOPROPYLIDENE)-GLYCEROLS

1966 ◽  
Vol 44 (15) ◽  
pp. 1787-1793 ◽  
Author(s):  
P. A. J. Gorin ◽  
T. Ishikawa
Keyword(s):  
Hydrogen Bonding ◽  
Chemical Synthesis ◽  
Infrared Absorption ◽  
Hydroxyl Group ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Absorption Studies ◽  
Cis And Trans

The cis- and trans-isomers of 1,2-O-(2′-hydroxyethylidene)-glycerol (I and II) and 1,2-O-(hydroxyisopropylidene)-glycerol (V and VI) were prepared and their configurations assigned by stereospecific chemical synthesis. Equilibration of 1,2-O-(2′-cis-hydroxyethylidene)-L-glycerol (I) in acidified chloroform gave mainly 1,3-O-(2′-cis-hydroxyethylidene)-glycerol (III). In the 1,2-O-(hydroxyisopropylidene)-glycerol series, equilibration data and infrared absorption studies showed that hydrogen bonding of the O-(hydroxyisopropylidene) hydroxyl group was more pronounced in the cis-isomers.

Cyanoacrylate Inhibitors of the Hill Reaction V. The Effect of Chirality on Inhibitor Binding

1987 ◽  
Vol 42 (6) ◽  
pp. 684-689 ◽  
Author(s):  
John L. Huppatz ◽  
John N. Phillips
Keyword(s):  
Phenyl Ring ◽  
Alkyl Substituent ◽  
Receptor Site ◽  
Optically Active ◽  
Hill Reaction ◽  
Inhibitor Binding ◽  
Level Of Activity ◽  
The Difference ◽  
The Hill

Optically active α-methylbenzylamino 2-cyanoacrylic esters were synthesized and assayed as inhibitors of the Hill reaction in isolated pea chloroplast fragments. The 5-isomers were more potent inhibitors than the S-isomers with discriminations of from ten to greater than 100-fold being observed. A β-alkyl substituent in the cyanoacrylate molecule affected both the level of activity and the difference in activity between the isomers. An α,α-dimethylbenzylamino derivative was also active at about the same level as the corresponding α-methylbenzylamino racemate. This result could be explained in terms of the orientation of the phenyl ring in the receptor site. Replacement of the α-methylbenzylamino group by other α-alkyl and α-phenyl substituents had little effect on activity. However, an α-benzyl group was beneficial.

scholarly journals Identification of Anthocyanin Compounds in Butterfly Pea Flowers (Clitoria ternatea L.) by Ultra Performance Liquid Chromatography/Ultraviolet Coupled to Mass Spectrometry

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4539
Author(s):  
Nguyen Minh Thuy ◽  
Vo Minh ◽  
Tran Ben ◽  
My Tuyen Thi Nguyen ◽  
Ho Ha ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Ultra Performance Liquid Chromatography ◽  
Negative Ion ◽  
Trans Isomers ◽  
Clitoria Ternatea ◽  
Flower Extract ◽  
Cis And Trans Isomers ◽  
Butterfly Pea ◽  
Cis And Trans

Butterfly pea flower have great sensory attraction, but they have not yet been used widely in Vietnam. Extracts of butterfly pea flowers can be used conveniently as a natural blue colorant for food products. In this study, the identification of anthocyanin compounds in butterfly pea flowers was performed by UPLC coupled with a UV and Mass spectrometer instrument. Positive and negative ion electrospray MS/MS chromatograms and spectra of the anthocyanin compounds were determined. By analyzing the chromatograms and spectra for each ion, five anthocyanins were identified in the butterfly pea flower extract; these were delphinidin-3-(6”‐p-coumaroyl)-rutinoside, cyanidin 3-(6”-p-coumaroyl)-rutinoside, delphinidin-3-(p-coumaroyl) glucose in both cis- and trans- isomers, cyanidin-3-(p-coumaroyl-glucoside) and delphinidin-3-pyranoside. Additionally, based on their intensity, it was determined that cyanidin-3-(p-coumaroyl-glucoside) was the most abundant anthocyanin, followed by cyanidin 3-(6”-p-coumaroyl)-rutinoside, delphinidin-3-(p-coumaroyl-glucoside), delphinidin-3-(6”-p-coumaroyl)-rutinoside and delphinidin-3-pyranoside. In this study, cyanidin derivatives were discovered in butterfly pea flower extract, where these compounds had not been detected in previous studies.

Unveiling the coexistence of cis- and trans-isomers in the hydrolysis of ZrO2: A coupled DFT and high-resolution photoelectron spectroscopy study

2020 ◽  
Vol 153 (24) ◽  
pp. 244308
Author(s):  
Ali Abou Taka ◽  
Mark C. Babin ◽  
Xianghai Sheng ◽  
Jessalyn A. DeVine ◽  
Daniel M. Neumark ◽  
...  
Keyword(s):  
High Resolution ◽  
Photoelectron Spectroscopy ◽  
Spectroscopy Study ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Hydrolysis Of
Sign in / Sign up

Export Citation Format

Share Document