scholarly journals Metal- and Oxidant-Free Photoinduced Aromatic Trifluoromethylation Performed in Aerated Gel Media: Determining the Effects on Yield and Selectivity

Molecules ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 29 ◽  
Author(s):  
Alex Abramov ◽  
Hendrik Vernickel ◽  
César Saldías ◽  
David Díaz Díaz
Keyword(s):  
Molecular Weight ◽  
Room Temperature ◽  
Homogeneous Solution ◽  
Product Distribution ◽  
Blocking Effect ◽  
Low Molecular Weight ◽  
Metal Free ◽  
Potential Benefits ◽  
Media Concentration ◽  
Reaction Media

In this work we have investigated the potential benefits of using supramolecular gel networks as reaction media to carry out air-sensitive metal-free light-induced trifluoromethylation of six-membered (hetero)arenes under aerobic conditions. This reaction was performed at room temperature (RT) using sodium triflinate (CF3SO2Na, Langlois’ reagent) as a source of radicals and diacetyl as electron donor. The effects of confinement in gel media, concentration of reactants, and type of light source on yield and product distribution were evaluated and compared to the results obtained in homogeneous solution. Four different low molecular weight (LMW) gelators were employed in this study. The results confirmed the blocking effect of the gel medium against reaction quenching by external oxygen, as well as a certain control on the kinetics and selectivity.

Production of low molecular weight esters using vegetable oils or butter oil as reaction media

2007 ◽  
Vol 52 (2) ◽  
pp. 201-209 ◽  
Author(s):  
Frank W. Welsh ◽  
Ross E. Williams ◽  
Shirley C. Chang ◽  
Chantel J. Dicaire
Keyword(s):  
Molecular Weight ◽  
Vegetable Oils ◽  
Low Molecular Weight ◽  
Butter Oil ◽  
Reaction Media

Effect of Various Curing Agents On the Chemical Stability of Epoxy Resins

CORROSION ◽  
1961 ◽  
Vol 17 (1) ◽  
pp. 11t-20t ◽  
Author(s):  
RONALD L. DeHOFF
Keyword(s):  
Molecular Weight ◽  
Chemical Stability ◽  
Epoxy Resins ◽  
Room Temperature ◽  
Low Molecular Weight ◽  
Curing Agent ◽  
Corrosion Prevention ◽  
Curing Agents ◽  
Outdoor Weathering ◽  
Better Than

Abstract The epoxy resins most widely used in corrosion prevention are liquids of low molecular weight which can be converted to hard, tough, chemically resistant polymers by the use of various curing agents. Unlike other thermosetting resins such as polyesters, the curing agents may produce chemical linkages in the final polymers that differ from those present in the uncured form. Hence, the properties of cured epoxy resins are likely dependent upon, and may even reflect the properties of the curing agent used. Some seven different epoxy resin systems were exposed to various chemical environments and evaluatd for changes in dimensional stability and flexural strengths over a six month period. From the data presented herein, only limited conclusions may be drawn. Heat cured systems fare better than room temperature cured systems in every case. Anhydride cured epoxy resins show greater resistance to outdoor weathering than amine cured systems. 5.4.5, 6.6.8

Room-temperature Sinterable Silver Nanoparticle Ink with Low-molecular-weight Poly(N-vinylpyrrolidone) Ligand

2013 ◽  
Vol 42 (3) ◽  
pp. 232-234 ◽  
Author(s):  
Mi Yeon Lee ◽  
Won Jin Lee ◽  
Arup Kumer Roy ◽  
Kang Seok Lee ◽  
Sung Young Park ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Silver Nanoparticle ◽  
Room Temperature ◽  
Low Molecular Weight ◽  
Nanoparticle Ink

Use of low molecular weight oligomers as non-volatile reaction media

Polymer ◽  
1998 ◽  
Vol 39 (25) ◽  
pp. 6513-6518
Author(s):  
Q Weng ◽  
X Ni ◽  
A Gopala ◽  
J Xu ◽  
P Heiden
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
Reaction Media

Influence of low molecular weight tail of polypropylene resin on the pore structure by room-temperature stretching

2013 ◽  
Vol 53 (12) ◽  
pp. 2594-2602 ◽  
Author(s):  
Lei Caihong ◽  
Wu Shuqiu ◽  
Xu Ruijie ◽  
Peng Xinlong ◽  
Shi Wenqiang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Pore Structure ◽  
Room Temperature ◽  
Low Molecular Weight

A Potential New RAFT - Click Reaction or a Cautionary Note on the Use of Diazomethane to Methylate RAFT-synthesized Polymers

2011 ◽  
Vol 64 (4) ◽  
pp. 433 ◽  
Author(s):  
Ming Chen ◽  
Graeme Moad ◽  
Ezio Rizzardo
Keyword(s):  
Molecular Weight ◽  
Methyl Methacrylate ◽  
Room Temperature ◽  
Click Reaction ◽  
Raft Polymerization ◽  
Dipolar Cycloaddition ◽  
Low Molecular Weight ◽  
Similar Reaction ◽  
Poly Methyl Methacrylate ◽  
End Groups

It has been found that diazomethane undergoes a facile 1,3‐dipolar cycloaddition with both dithiobenzoate RAFT agents and the dithiobenzoate end‐groups of polymers formed by RAFT polymerization. Thus, 2‐cyanoprop‐2‐yl dithiobenzoate on treatment with diazomethane at room temperature provided a mixture of stereoisomeric 1,3‐dithiolanes in near quantitative (>95%) yield. A low‐molecular‐weight RAFT‐synthesized poly(methyl methacrylate) with dithiobenzoate end‐groups underwent similar reaction as indicated by immediate decolourization and a quantitative doubling of molecular weight. Higher‐molecular‐weight poly(methyl methacrylate)s were also rapidly decolourized by diazomethane and provided a product with a bimodal molecular weight distribution. Under similar conditions, the trithiocarbonate group does not react with diazomethane.

Encapsulated Laccases for the Room-Temperature Oxidation of Aromatics: Towards Synthetic Low-Molecular-Weight Lignins

ChemSusChem ◽  
2016 ◽  
Vol 9 (7) ◽  
pp. 756-762 ◽  
Author(s):  
Lucia Pistone ◽  
Gianluca Ottolina ◽  
Sudipta De ◽  
Antonio A. Romero ◽  
Lígia O. Martins ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Room Temperature ◽  
Low Molecular Weight ◽  
Temperature Oxidation
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