Vinyl ether hydrolysis. XII. Use of cis–trans isomerism to probe the reaction mechanism

1978 ◽  
Vol 56 (4) ◽  
pp. 461-464 ◽  
Author(s):  
Y. Chiang ◽  
A. J. Kresge ◽  
C. I. Young
Keyword(s):  
Reaction Mechanism ◽  
Vinyl Ether ◽  
Hydrolysis Reaction ◽  
Trans Isomers ◽  
Vinyl Methyl ◽  
Reaction Conditions ◽  
Carbonium Ion ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Hydrolysis Of

Rates of hydrolysis of cis- and trans-β-phenylvinyl methyl ethers, cis- and trans-β-(p-nitrophenyl)vinyl methyl ethers, and cis- and trans-β-cyanovinyl ethyl ethers were measured in concentrated (10–55 wt%) aqueous perchloric acids. The results show that these cis and trans isomers do not interconvert under the hydrolysis reaction conditions, and that formation of the alkoxy carbonium ion intermediate in these reactions is therefore not reversible.

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

The Effect of N-Substitution on the Rates of Saponification of Some Amino Acid Esters

1971 ◽  
Vol 49 (21) ◽  
pp. 3468-3476 ◽  
Author(s):  
Jocelyn E. Purdie ◽  
N. Leo Benoiton
Keyword(s):  
Amino Acid ◽  
Methyl Esters ◽  
Activation Parameters ◽  
Side Chain ◽  
Amino Acid Esters ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Hydrolysis Of ◽  
Acid Esters

The saponification rates (measured at 25 ° by a titrimetric method) of the unprotonated forms of the methyl esters of glycine, alanine, leucine, valine, and phenylalanine were compared with those of the N-methyl, the N-acetyl, and the N-acetyl, N-methylamino acid analogues. N-Acetylation slightly increased or decreased the rate but N-methylation caused a reduction by as much as a factor of ten, depending on the complexity of the side-chain. The esters of the N-acetyl, N-methylamino acids, which exist as cis and trans isomers, were saponified at rates intermediate between those of the esters of the N-acetylamino acids and N-methylamino acids. Activation parameters were obtained for the phenylalanine and leucine derivatives. N-Methylation resulted in an increase in ΔH≠ and ΔS≠ which was attributed in part to solvation effects. The hydrolysis of the cationic esters of glycine and alanine was still evident at pH 11.0. N-Methylation had little effect on the rates of saponification of the charged forms.

scholarly journals Alkaline Hydrolysis of the cis and trans Isomers of the Cyclic Phosphinate: 1-Oxo-1-ethoxy-2,2,3,4,4-pentamethyl-phospha-cyclobutan.

1967 ◽  
Vol 21 ◽  
pp. 1587-1591 ◽  
Author(s):  
Knut Bergesen ◽  
Ole Østerberg ◽  
Thor A. Bak ◽  
Pär Holmberg ◽  
G. Eriksson ◽  
...  
Keyword(s):  
Alkaline Hydrolysis ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Hydrolysis Of

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.

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