Carbon-13 Resonance Spectroscopic Studies on the Formation of Borate and Diphenylborinate Complexes of Polyhydroxy Compounds

1973 ◽  
Vol 51 (19) ◽  
pp. 3277-3286 ◽  
Author(s):  
Philip A. J. Gorin ◽  
Mytosk Mazurek
Keyword(s):  
Molecular Weight ◽  
Magnetic Resonance ◽  
Spectroscopic Studies ◽  
Sodium Tetraborate ◽  
Low Molecular Weight ◽  
Hydroxyl Groups ◽  
Polyhydroxy Compounds ◽  
Borate Complex ◽  
Equilibrium Reactions ◽  
Borate Complexes

On complexing with sodium tetraborate the 13C magnetic resonance (c.m.r.) spectra of certain sugars contain considerably broadened signals. Replacement of the reagent with sodium diphenylborinate resulted in spectra with sharp singlets corresponding to the diphenylborinate complex, indicating that 13C-11B coupling likely does not occur. Most of the broadening is due rather to either the presence of more than one conformer of the borate complex or the rapid interconversion of the compound with borate complexes of types II and III. In one group of experiments the complexing of diphenylborinate with several low molecular weight sugars and polysaccharides was followed through c.m.r. spectroscopy. In another, complexing was observed with pyranosides having 1,3-hydroxyl groups with orientations that were almost diaxial. In the equilibrium reactions the approximate extent of complexing was estimated and with compounds that can form more than one complex, such as glycerol, the number and structures of the complexes were determined.

Composition of low molecular weight impurities in dimethylmethylpheylsiloxane rubbers with terminal hydroxyl groups

2020 ◽  
Vol 86 (11) ◽  
pp. 20-27
Author(s):  
A. M. Filippov ◽  
N. Yu. Semenkova ◽  
S. M. Gorelov ◽  
T. I. Shulyatieva ◽  
P. A. Storozhenko
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
Hydroxyl Groups

The Chemistry of Phenol-Formaldehyde Resin Vulcanization of EPDM: Part I. Evidence for Methylene Crosslinks

1995 ◽  
Vol 68 (5) ◽  
pp. 717-727 ◽  
Author(s):  
Martin van Duin ◽  
Aniko Souphanthong
Keyword(s):  
Molecular Weight ◽  
Phenol Formaldehyde ◽  
Polymer System ◽  
Phenol Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Low Molecular Weight ◽  
Hydroxyl Groups ◽  
Reaction Products ◽  
Cure Reaction ◽  
Weight Model

Abstract The application of phenol-formaldehyde resins as crosslinking agents is increasing in importance due to the good high temperature properties of the corresponding vulcanizate and the use in thermoplastic vulcanizates. With respect to the chemistry of phenol-formaldehyde cure (reaction mechanism and structure of crosslink) there are still problems that have to be resolved. The reaction products of the phenol-formaldehyde resin curing of EPDM, contain 2-ethylidene norbornene (ENB) as the third monomer, have been studied. Since such an investigation is rather difficult to perform for the polymer system, a low molecular weight model for EPDM was used: 2-ethylidene norbornane (ENBH). Reaction of ENBH and a resole results in scission of the dimethylene ether bridges, i.e. in degradation of the resole into mono-, bis- and terisooctylphenol units. These are consequently converted into products, consisting of two ENBH molecules linked by mono-, bis- and terisooctylphenol units. The solid resole seems to be a technological solution for storing phenol in combination with formaldehyde. These results support the use of 2-hydroxymethylphenol (HMP) as a low molecular weight model for the resole. At low temperatures and/or short reaction times HMP oligomers (= resoles) and HMP oligomers linked to one ENBH molecule are formed, which are converted into ENBH/HMP (1:1) condensation products. The reaction products of ENBH with both the resole and HMP are shown to contain methylene linked structures, as demonstrated by the formation of monisooctylphenol crosslinks and the presence of residual unsaturation and hydroxyl groups, besides chroman linked structures. This is the first experimental evidence that during phenol-formaldehyde resin cure of rubber, formation of methylene bridges occurs.

Acid-labile poly(amino alcohol ortho ester) based on low molecular weight polyethyleneimine for gene delivery

2017 ◽  
Vol 32 (3) ◽  
pp. 349-361 ◽  
Author(s):  
Jun Wang ◽  
Lei Zhang ◽  
Xin Wang ◽  
Shengxiang Fu ◽  
Guoqing Yan
Keyword(s):  
Molecular Weight ◽  
Amino Alcohol ◽  
Water Solubility ◽  
Transfection Efficiency ◽  
Enzymatic Digestion ◽  
Low Molecular Weight ◽  
Hydroxyl Groups ◽  
Ortho Ester ◽  
Human Neuroblastoma ◽  
Acid Labile

A series of acid-labile poly(amino alcohol ortho ester) (POEeis) were synthesized through ring-opening polymerization between diglycidyl ethers with ortho ester bonded and low molecular weight polyethyleneimine by various feed molar ratios. The obtain POEei 1 and POEei 2 exhibited clear kinetic of degradation and condensed plasmid DNA into nanoparticles of suitable sizes (250–300 nm) and positive zeta potentials (+20–30 mV) while protecting DNA from enzymatic digestion. Further, these polymers have uniform distribution of abundant hydroxyl groups, which could improve their water solubility, biocompatibility, and lower protein adsorption. Significantly, ortho ester groups in POEeis main-chains could hydrolyze rapidly at acidic endosomal pH, resulting in intracellular DNA release and diminished material toxicity. MTT assay revealed that all the polymers exhibited much lower cytotoxicity than 25 kDa PEI in the human neuroblastoma SH-SY5Y cells. Moreover, the transfection efficiency of POEei 1 was higher than 25 kDa PEI in serum-free medium or 10% serum medium.

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