Supporting Electrolyte in Indirect Electrolytic Reactions.

SummaryThe range of applications of cellulose, a glucose-based polysaccharide, is limited by its inherently poor mechanical properties. The grafting of synthetic polymer chains by, for example, a “grafting from” process may provide the means to broaden the range of applications. The nitroxide-mediated polymerization (NMP) method is a technique of choice to control the length, the composition and the architecture of the grafted copolymers. Nevertheless, cellulose is difficult to solubilize in organic media because of inter- and intramolecular hydrogen bonds. One possibility to circumvent this limitation is to solubilize cellulose in N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMA) with 5 to 10 wt % of lithium salts (LiCl or LiBr), and carry out grafted polymerization in this medium. The stability of nitroxides such as SG1 has not been studied under these conditions yet, even though these parameters are of crucial importance to perform the graft modification of polysaccharide by NMP. The aim of this work is to offer a model study of the stability of the SG1 nitroxide in organic media in the presence of unprotected glucose or cellobiose (used as a model of cellulose) and in the presence of lithium salts (LiBr or LiCl) in DMF or DMA.Contrary to TEMPO, SG1 proved to be stable in the presence of unprotected sugar, even with an excess of 100 molar equivalents of glucose. On the other hand, lithium salts in DMF or DMA clearly degrade SG1 nitroxide as proven by electron-spin resonance measurements. The instability of SG1 in these lithium-containing solvents may be explained by the acidification of the medium by the hydrolysis of DMA in the presence of LiCl. This, in turn, enables the disproportionation of the SG1 nitroxide into an unstable hydroxylamine and an oxoammonium ion.Once the conditions to perform an SG1-based nitroxide-mediated graft polymerization from cellobiose have been established, the next stage of this work will be the modification of cellulose and cellulose derivatives by NMP.

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“…10. The redox potential of the reduction of Li + /Li in DMF is around −2.1 V as already reported [31]. …”

Section: Resultssupporting

confidence: 79%

Stability of SG1 nitroxide towards unprotected sugar and lithium salts: a preamble to cellulose modification by nitroxide-mediated graft polymerization

Moreira¹,

Charles²,

Major³

et al. 2013

Beilstein J. Org. Chem.

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“…Among the problems studied were the electrochemistry of sulfur adsorbed on carbon [241], the carbon prepared by electrolytic reduction of polytetrafluoroethylene [242][243][244][245], and the TiO 2 electrodes modified by Nafion [246,247]. Pt and other solid electrodes were used in the institute [248,249], for example, for study of adsorption [250][251][252][253][254][255][256][257][258]. The electrochemical instrumentation was digitalized, and by 1980, the experiments were controlled on-line by a small computer of institute's construction.…”

Section: Academy Institutesmentioning

confidence: 99%

“…For example, the idea of vector-polarography was further developed by Bryksin, Petrii, and coworkers [248]. In 1960, Tsfasman has published the book "Electronic Polarographs" [249]. The list of references proves that he knew all the important Western publications, in both journals and books; and he noted in the preface, this was the first book devoted only to polarographs, i.e., to polarographic instruments.…”

Section: Semёn Borisovich Tsfasman and Ivan Yemelyanovichmentioning

confidence: 99%

“…During that time he worked in a group of highly talented enthusiastic people at the TSLA, headed by Semën Tsfasman. The references [245,246,248,249,255,[257][258][259][260][261][262][263][264][265][266] give some impression of the achievements of Tsfasman and Bryksin as inventors and designers of electrochemical instrumentation. The patent relating to the measurement of the capacitance of the electrical double layer [266], appeared, when Ivan Yemelyanovich was no longer.…”

Section: Semёn Borisovich Tsfasman and Ivan Yemelyanovichmentioning

confidence: 99%

“…These systems became the subject of investigations in the early 1970s independently by three groups of researchers [248][249][250][251][252]. The first publication was the article by Lund and coworkers [248]; our work, fragments of which I reported in Riga's EKhOS-73 [250], was submitted by Frumkin for publication in Doklady AN SSSR 19 [251].…”

Section: Homogeneous Electrocatalysismentioning

confidence: 99%

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Supporting Electrolyte in Indirect Electrolytic Reactions.

Cited by 24 publications

References 0 publications

Stability of SG1 nitroxide towards unprotected sugar and lithium salts: a preamble to cellulose modification by nitroxide-mediated graft polymerization

Stability of SG1 nitroxide towards unprotected sugar and lithium salts: a preamble to cellulose modification by nitroxide-mediated graft polymerization

Electrochemistry in a Divided World

Elektro-Deblockierung — Elektrochemische Abspaltung von Schutzgruppen

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