scholarly journals An Oxidation Study of Phthalimide-Derived Hydroxylactams

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 548
Author(s):  
Bernard L. Adjei ◽  
Frederick A. Luzzio
Keyword(s):  
Silica Gel ◽  
Systematic Study ◽  
Special Interest ◽  
Scale Up ◽  
Reaction Times ◽  
Pyridinium Chlorochromate ◽  
Oxidation Study ◽  
Full Conversion ◽  
Oxidation System

A systematic study of the oxidation of 3-hydroxy-2-substituted isoindolin-1-ones (hydroxylactams) and their conversion to the corresponding phthalimides was undertaken using three oxidants. Of special interest was the introduction of nickel peroxide (NiO2) as an oxidation system for hydroxylactams and comparison of its performance with the commonly used pyridinium chlorochromate (PCC) and iodoxybenzoic acid (IBX) reagents. Using a range of hydroxylactams, optimal conversions of these substrates to the corresponding imides was achieved with 50 equivalents of freshly prepared NiO2 in refluxing toluene over 5–32 h reaction times. By comparison, oxidations of the same substrates using PCC/silica gel (three equivalents) and IBX (three equivalents) required oxidation times of 1–3 h for full conversion but required lengthier purification. While nominal amounts (~25 mg) of substrate hydroxylactams were used to ascertain conversion, scale-up procedures using all three methods gave good to excellent isolated yields of imides.

scholarly journals Ureido Functionalization through Amine-Urea Transamidation under Mild Reaction Conditions

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1583
Author(s):  
Natalia Guerrero-Alburquerque ◽  
Shanyu Zhao ◽  
Daniel Rentsch ◽  
Matthias M. Koebel ◽  
Marco Lattuada ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Reaction Times ◽  
Reaction Rates ◽  
Secondary Amines ◽  
Isocyanic Acid ◽  
Advantages And Disadvantages ◽  
Major Disadvantage ◽  
Wide Range ◽  
Potential Alternative ◽  
Full Conversion

Ureido-functionalized compounds play an indispensable role in important biochemical processes, as well as chemical synthesis and production. Isocyanates, and KOCN in particular, are the preferred reagents for the ureido functionalization of amine-bearing compounds. In this study, we evaluate the potential of urea as a reagent to graft ureido groups onto amines at relatively low temperatures (<100 °C) in aqueous media. Urea is an inexpensive, non-toxic and biocompatible potential alternative to KOCN for ureido functionalization. From as early as 1864, urea was the go-to reagent for polyurea polycondensation, before falling into disuse after the advent of isocyanate chemistry. We systematically re-investigate the advantages and disadvantages of urea for amine transamidation. High ureido-functionalization conversion was obtained for a wide range of substrates, including primary and secondary amines and amino acids. Reaction times are nearly independent of substrate and pH, but excess urea is required for practically feasible reaction rates. Near full conversion of amines into ureido can be achieved within 10 h at 90 °C and within 24 h at 80 °C, and much slower reaction rates were determined at lower temperatures. The importance of the urea/amine ratio and the temperature dependence of the reaction rates indicate that urea decomposition into an isocyanic acid or a carbamate intermediate is the rate-limiting step. The presence of water leads to a modest increase in reaction rates, but the full conversion of amino groups into ureido groups is also possible in the absence of water in neat alcohol, consistent with a reaction mechanism mediated by an isocyanic acid intermediate (where the water assists in the proton transfer). Hence, the reaction with urea avoids the use of toxic isocyanate reagents by in situ generation of the reactive isocyanate intermediate, but the requirement to separate the excess urea from the reaction product remains a major disadvantage.

scholarly journals Diels–Alder reactions of myrcene using intensified continuous-flow reactors

2017 ◽  
Vol 13 ◽  
pp. 120-126 ◽  
Author(s):  
Christian H Hornung ◽  
Miguel Á Álvarez-Diéguez ◽  
Thomas M Kohl ◽  
John Tsanaktsidis
Keyword(s):  
Continuous Flow ◽  
Flow Reactor ◽  
Scale Up ◽  
Reaction Times ◽  
Alder Reaction ◽  
Diels Alder ◽  
Flow Reactors ◽  
Diels Alder Reaction ◽  
Naturally Occurring ◽  
Continuous Flow Reactors

This work describes the Diels–Alder reaction of the naturally occurring substituted butadiene, myrcene, with a range of different naturally occurring and synthetic dienophiles. The synthesis of the Diels–Alder adduct from myrcene and acrylic acid, containing surfactant properties, was scaled-up in a plate-type continuous-flow reactor with a volume of 105 mL to a throughput of 2.79 kg of the final product per day. This continuous-flow approach provides a facile alternative scale-up route to conventional batch processing, and it helps to intensify the synthesis protocol by applying higher reaction temperatures and shorter reaction times.

Semantics

2018 ◽  
Author(s):  
Mark Crimmins
Keyword(s):  
Systematic Study ◽  
Special Interest ◽  
Semantic Theory ◽  
Current Work ◽  
Independent Interest ◽  
Semantic Function ◽  
The World

Semantics is the systematic study of meaning. Current work in this field builds on the work of logicians and linguists as well as of philosophers. Philosophers are interested in foundational issues in semantics because these speak to the nature of meaning, as it embeds in our thinking and in our relations to each other and to the world. Of special interest are questions about how a semantic theory should respect the connections of meaning to truth and to understanding. In addition, numerous semantic problems concerning particular linguistic constructions bear philosophical interest, sometimes because the problems are important to resolving foundational semantical issues, sometimes because philosophical problems of independent interest are expressed using the constructions, and sometimes because clarity about the semantic function of the constructions enables clarity in the development of philosophical theories and analyses.

scholarly journals Environmental-Friendly Synthesis of Alkyl Carbamates from Urea and Alcohols with Silica Gel Supported Catalysts

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 579
Author(s):  
Yubo Ma ◽  
Lei Wang ◽  
Xiaodong Yang ◽  
Ronghui Zhang
Keyword(s):  
Silica Gel ◽  
Supported Catalysts ◽  
Scale Up ◽  
Supported Catalyst ◽  
Catalyst System ◽  
Ethyl Carbamate ◽  
Impregnation Method ◽  
Methyl Ethyl ◽  
Environmental Friendly ◽  
Alkyl Carbamate

TiO2/SiO2, Cr2O3-NiO/SiO2, and TiO2-Cr2O3/SiO2 were prepared by the impregnation method for alkyl carbamate synthesis using urea as the carbonyl source. Up to 97.5% methyl carbamate yield, 97% ethyl carbamate yield, and 96% butyl carbamate yield could be achieved, respectively. The catalysts were characterized by ICP-AES, BET, XRD, XPS, NH3-TPD, and EPMA. Catalytic activity investigation revealed that TiO2/SiO2, Cr2O3-NiO/SiO2, and TiO2-Cr2O3/SiO2 were effective catalysts for methyl carbamate (MC), ethyl carbamate (EC), and butyl carbamate (BC), respectively. The recycling tests suggested that these silica gel supported catalyst system is active, stable, and reusable. A total of 96–97% alkyl carbamate (methyl, ethyl, and butyl) could be obtained in a 2 L autoclave, and these data suggested that our catalyst system is relatively easy to scale up.

Ferric hydrogensulphate as a recyclable catalyst for the synthesis of fluorescein derivatives

2011 ◽  
Vol 65 (4) ◽  
Author(s):  
Hossein Eshghi ◽  
Narges Mirzaie
Keyword(s):  
Phthalic Anhydride ◽  
Scale Up ◽  
Reaction Times ◽  
Catalytic Amount ◽  
Recyclable Catalyst ◽  
Environmentally Benign ◽  
Absorption And Emission ◽  
Emission Properties ◽  
Benign Nature ◽  
High Yields

AbstractPolycondensation reactions of phenols with phthalic anhydride were carried out in the presence of ferric hydrogensulphate under melt conditions. The reactions proceeded in short reaction times by using a catalytic amount of Fe(HSO4)3 and the corresponding fluorescein derivatives were obtained in high yields. The simplicity, scale-up, along with the use of an inexpensive, non-toxic, recyclable catalyst of an environmentally benign nature, are other remarkable features of the procedure. The absorption and emission properties of these fluorescein derivatives were studied.

scholarly journals P2O5/SiO2as a New, Efficient and Reusable Catalyst for Preparation of 4,4′-Epoxydicoumarins Under Solvent-free Conditions

2011 ◽  
Vol 8 (4) ◽  
pp. 1626-1631 ◽  
Author(s):  
Liqiang Wu ◽  
Xiao Wang
Keyword(s):  
Silica Gel ◽  
Low Cost ◽  
Reaction Times ◽  
Catalytic Amount ◽  
Phosphorus Pentoxide ◽  
Solvent Free ◽  
Reusable Catalyst ◽  
Solvent Free Conditions ◽  
High Yields

An efficient solvent-free procedure for the preparation of 4,4′-epoxydicoumarins via the ondensation of 4-hydroxycoumarin with aldehydes in the presence of catalytic amount of phosphorus pentoxide/silica gel at 110°C is described. The advantages of this method are generality, high yields, short reaction times, ease of product isolation, low cost and ecologically friendly.

A Facile Oxidation of Alcohols Using Pyridinium Chlorochromate/Silica Gel

1999 ◽  
Vol 76 (7) ◽  
pp. 974 ◽  
Author(s):  
Frederick A. Luzzio ◽  
Richard W. Fitch ◽  
William J. Moore ◽  
Kelli J. Mudd
Keyword(s):  
Silica Gel ◽  
Pyridinium Chlorochromate ◽  
Oxidation Of Alcohols

Scale-up of electrochemical oxidation system for treatment of produced water generated by Brazilian petrochemical industry

2014 ◽  
Vol 21 (14) ◽  
pp. 8466-8475 ◽  
Author(s):  
Elisama Vieira dos Santos ◽  
Shirley Feitosa Machado Sena ◽  
Djalma Ribeiro da Silva ◽  
Sergio Ferro ◽  
Achille De Battisti ◽  
...  
Keyword(s):  
Electrochemical Oxidation ◽  
Petrochemical Industry ◽  
Produced Water ◽  
Scale Up ◽  
Oxidation System

scholarly journals A Task-Specific Ionic-Liquid-Mediated Solvent-Free Protocol for Direct Access to Dimethyl Acetal Protected Benzimidazole 2-Carboxaldehydes

SynOpen ◽  
2020 ◽  
Vol 04 (04) ◽  
pp. 89-95
Author(s):  
Swapan Majumdar ◽  
Barnali Deb ◽  
Ankita Chakraborty ◽  
Jewel Hossain
Keyword(s):  
Ionic Liquid ◽  
Scale Up ◽  
Reaction Times ◽  
Dimethyl Acetal ◽  
Single Step ◽  
Direct Access ◽  
Imidazolium Ionic Liquid ◽  
Reaction Conditions ◽  
High Yields ◽  
Task Specific Ionic Liquid

AbstractA robust and straightforward protocol has been developed for the synthesis of a diverse array of dimethyl acetal protected benz­imidazole-2-carboxaldehydes by reacting various 2-amino aniline derivatives with methyl 4,4-dimethoxy-3-oxobutanoate using the task-specific­ imidazolium ionic liquid (HBIm·TFA) as a promoter for N-C/C-N annulation processes. The present protocol offers several advantages over existing protocols, such as single-step process, short reaction times, very mild reaction conditions, high yields, ease of purification, recovery and reusability of the catalyst, and scale-up of the reaction.

Sign in / Sign up

Export Citation Format

Share Document