Preparation of 1-Adamantyl Ketones: Structure, Mechanism of Formation and Biological Activity of Potential By-products.

ChemInform ◽  
2006 ◽  
Vol 37 (39) ◽  
Author(s):  
Robert Vicha ◽  
Marek Necas ◽  
Milan Potacek
Keyword(s):  
Biological Activity ◽  
Mechanism Of Formation ◽  
By Products

Preparation of 1-Adamantyl Ketones: Structure, Mechanism of Formation and Biological Activity of Potential By-Products

2006 ◽  
Vol 71 (5) ◽  
pp. 709-722 ◽  
Author(s):  
Robert Vícha ◽  
Marek Nečas ◽  
Milan Potáček
Keyword(s):  
Biological Activity ◽  
Grignard Reagents ◽  
Adamantane Derivatives ◽  
Mechanism Of Formation ◽  
Carbonyl Chloride ◽  
Leaving Group ◽  
Ar Process ◽  
By Products

Reactions between adamantane-1-carbonyl chloride and several Grignard reagents as well as interactions with solvents have been examined. Some new and unexpected adamantane derivatives were isolated, fully characterized and their biological activity determined. In particular, an unexpected isochromanone 16 was formed in an SEAr process, in which a stable hydrocarbon was the leaving group.

Amorphous Polymeric Dithiazine apDTZ Solid Fouling: Critical Review, Analysis and Solution of an Ongoing Challenge in Triazine-Based Hydrogen Sulphide Mitigation

2021 ◽  
Author(s):  
Grahame Taylor ◽  
Jonathan Wylde ◽  
Walter Samaniego ◽  
Ken Sorbie
Keyword(s):  
Hydrogen Sulphide ◽  
Reaction Pathway ◽  
Theoretical Calculations ◽  
Mechanism Of Formation ◽  
Review Analysis ◽  
Operational Problem ◽  
Depth Study ◽  
The Common ◽  
By Products ◽  
A Current

Abstract Despite attempts to inhibit or avoid the formation of fouling deposits (polymeric amorphous dithiazine or apDTZ for short) from the use of MEA triazine, this remains a major operational problem and limits the use of this most popular and ubiquitous hydrogen sulphide (H2S) scavenger. This paper (a) reviews and summarizes previous work, (b) provides fresh insights into the reaction product and mechanism of formation, (c) proposes an effective method of removal, and (d) proposes some mechanisms of apDTZ digestion. The mechanism of apDTZ formation is discussed and reasoning is provided from a variety of perspectives as to the mechanism of MEA-triazine reaction with H2S. These include basicity and nucleophilic substitution considerations, steric properties and theoretical calculations for electron density. Novel procedures to chemically react with and destroy this solid fouling are presented with an in-depth study and experimental verification of the underlying chemistry of this digestion process. A review of agents to chemically destroy apDTZ is undertaken and a very effective solution has been found in peroxyacetic acid, which is much more powerful and effective than previously suggested peroxides. The structure of amorphous polymeric dithiazine is emphasized and the reason why this fouling cannot be 1,3,5-trithiane is stressed. This work therefore overcomes a current industry misconception by providing insight on two major paradoxes in the reaction pathway; namely i) why the thiadiazine reaction product from tris hydroxyethyl triazine (MEA triazine) is never observed and ii) why does the dithiazine in all cases never progress to the trithiane (3rd sulphur molecule substitution)? The latter issue is probably the biggest misconception in the industry and literature regarding triazine and H2S reactions. Many reasons for this are put forward and the common misconception of "overspent" triazine is refuted. A very effective chemical reaction that results in soluble by-products, counteracting the problems produced by this intractable polymer is found and their composition is proposed and experimentally verified.

Flavan derivatives. XVII. Epimerization of the benzylic 4-hydroxyl group in flavan-3,4-diols and the formation of 4-alkyl ethers by solvolysis

1967 ◽  
Vol 20 (10) ◽  
pp. 2151
Author(s):  
JW Clark-Lewis ◽  
LR Williams
Keyword(s):  
Aqueous Media ◽  
Cyclic Ether ◽  
Hydroxyl Group ◽  
Mechanism Of Formation ◽  
Enol Ether ◽  
Mild Conditions ◽  
Ethoxyl Group ◽  
Alkyl Ethers ◽  
By Products ◽  
Thermodynamic Factors

Epimerization and solvolysis of the benzylic 4-hydroxyl group is shown to be a general property of flavan-3,4-diols, and the diols give 4- ethoxyflavan-3-ols with ethanolic hydrochloric acid (1%). The diols are first converted into epimeric mixtures of 3,4-cis- and 3,4-trans-diols and in aqueous media cis-cis-flavan-3,4-diols yield mainly 2,3-cis-3,4- trans-diols. These 2,3-cis-3,4-diols undergo solvolysis to yield 2,3- cis-3,4-trans-4-ethoxyflavan-3-ols in which the 3,4-trans- stereochemistry is controlled by participation of the neighbouring 3ax- hydroxyl group. 2,3-trans-Flavan-3,4-diols give mixtures of trans- trans-diols and 2,3-trans-3,4-cis-diols and solvolysis first yields 2.3-trans-3,4-cis-4-ethoxyflavan-3-ols and then mixtures of the 3,4- cis- and 3,4-trans-ethers; the final proportion of these two ethers is controlled by thermodynamic factors. Solvolysis under mild conditions gives minor products considered to be 3-oxoflavans (or their enols) because of their immediate conversion into antho-cyanidins by cold acids in the presence of air, and from the formation of an enol-ether on prolonged solvolysis under more vigorous conditions. The relevance of these observations to the mechanism of formation of anthocyanidins from flavan-3,4-diols is discussed. Other by-products of solvolysis reactions include a dimeric cyclic ether (dioxan derivative) of 2,3- trans-3,4-cis-7,8,4?-trimethoxyflavan-3,4-diol. The structure and stereochemistry of solvolysis products were established by N.M.R. data; the 4-ethoxyl group in the ethers generally gave rise to an ABX3 multiplet.

scholarly journals Biological activity and sensory evaluation of cocoa by-products NADES extracts used in food fortification

2020 ◽  
Vol 66 ◽  
pp. 102514
Author(s):  
Panić Manuela ◽  
Saša Drakula ◽  
Giancarlo Cravotto ◽  
Robert Verpoorte ◽  
Mirjana Hruškar ◽  
...  
Keyword(s):  
Biological Activity ◽  
Sensory Evaluation ◽  
Food Fortification ◽  
By Products

Westphalen rearrangement. Mechanism of formation of 5α-acetoxy derivatives

1979 ◽  
Vol 44 (1) ◽  
pp. 234-245 ◽  
Author(s):  
Pavel Kočovský ◽  
Václav Černý ◽  
František Tureček
Keyword(s):  
Mechanism Of Formation ◽  
Neighboring Group ◽  
Group Participation ◽  
Rearrangement Mechanism ◽  
Neighboring Group Participation ◽  
By Products

5α-Acetoxy derivatives formed as by-products in the course of Westphalen rearrangement of [5-18O]-5-hydroxy-5α-cholestanes Ia and Ib are shown to preserve their 18O content. This fact rules out previously proposed neighboring group participation of the 6β-substituent involving a 5β,6β-„onium" intermediate (F).

Impact of extraction processes on phytochemicals content and biological activity of Citrus × clementina Hort. Ex Tan. leaves: New opportunity for under-utilized food by-products

2020 ◽  
Vol 127 ◽  
pp. 108742 ◽  
Author(s):  
Mariarosaria Leporini ◽  
Rosa Tundis ◽  
Vincenzo Sicari ◽  
Teresa Maria Pellicanò ◽  
Annabelle Dugay ◽  
...  
Keyword(s):  
Biological Activity ◽  
Extraction Processes ◽  
By Products

Synthesis of Analogues of GABA. II. 4-Alkyl-4-aminobut-2-enoic Acids and a New Synthesis of Some Vinyl α-Amino Acids

1979 ◽  
Vol 32 (11) ◽  
pp. 2507 ◽  
Author(s):  
RD Allan
Keyword(s):  
Amino Acids ◽  
Biological Activity ◽  
Gaba Uptake ◽  
Synthetic Route ◽  
Conformationally Restricted ◽  
Enzyme Systems ◽  
New Synthesis ◽  
Methylene Groups ◽  
By Products

A series of 4-alkyl-4-aminobut-2-enoic acids (2)-(5) has been prepared as conformationally restricted analogues of GABA. The synthetic route which involved allylic bromination followed by displacement with ammonia also gave vinyl glycine analogues (7)-(9) as readily purified by-products of the reaction. The low biological activity in vitro against GABA uptake, binding and enzyme systems of (E)-2-aminocyclohexylideneacetic acid (4) and (E)-2-aminocyclopentylideneacetic acid (5) has been interpreted in terms of steric hindrance by the ring-forming methylene groups at the particularactive sites concerned.

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