scholarly journals Amino-functionalized (meth)acryl polymers by use of a solvent-polarity sensitive protecting group (Br-t-BOC)

2016 ◽  
Vol 12 ◽  
pp. 245-252
Author(s):  
Helmut Ritter ◽  
Monir Tabatabai ◽  
Markus Herrmann
Keyword(s):  
Free Radical ◽  
Nmr Spectroscopy ◽  
Free Amino ◽  
Solvent Polarity ◽  
Protecting Group ◽  
Amino Groups ◽  
Neighboring Group ◽  
H Nmr ◽  
Polarity Sensitive ◽  
Kinetics Of

We describe the synthesis of bromo-tert-butyloxycarbonyl (Br-t-BOC)-amino-protected monomers 2-((1-bromo-2-methylpropan-2-yl)oxycarbonylamino)ethyl (meth)acrylate 3a,b. For this purpose, 2-isocyanatoethyl (meth)acrylate 1a,b was reacted with 1-bromo-2-methylpropan-2-ol (2a). The free radical polymerization of (Br-t-BOC)-aminoethyl (meth)acrylates 3a,b yielded poly((Br-t-BOC)-aminoethyl (meth)acrylate) 6a,b bearing protected amino side groups. The subsequent solvolysis of the Br-t-BOC function led to the new polymers poly(2-aminoethyl (meth)acrylate) 8a,b with protonated free amino groups. The monomers and the resulting polymers were thoroughly characterized by 1H NMR, IR, GPC and DSC methods. The kinetics of the deprotection step was followed by 1H NMR spectroscopy. The solvent polarity and neighboring group effects on the kinetics of deprotection are discussed.

scholarly journals Kinetics of Free Radical Polymerization of N-Substituted Amides and Their Structural Implications

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Anca Aldea ◽  
Ana-Maria Albu ◽  
Alina Nicolescu ◽  
Victorita Tecuceanu
Keyword(s):  
Hydrogen Bonding ◽  
Free Radical ◽  
Nitrogen Atom ◽  
Steric Hindrance ◽  
Solvent Polarity ◽  
Hydrogen Bonding Interaction ◽  
H Nmr ◽  
Bonding Interaction ◽  
Kinetics Of ◽  
C Nmr

Two N-substituted amides (N-acryloyl morpholine and N-methyl-N-vinylacetamide) were polymerized in different solvents using radical initiator. The tacticity of obtained polymers was determined by 400 MHz1H-NMR and13C-NMR. At a given temperature, the syndiotacticity increased with increasing the solvent polarity. This solvent effect may be related to the hydrogen bonding interaction among solvent, monomer, and/or growing species. A peculiar aspect regards the steric hindrance at the nitrogen atom.

A NMR Study of the Exchange Kinetics of the Nonamethylimidodiphosphoramide with its Complexes of Diamagnetic Cations

1978 ◽  
Vol 33 (6) ◽  
pp. 684-685 ◽  
Author(s):  
P. R. Rubini ◽  
L. Rodehüser ◽  
J.-J. Delpuech
Keyword(s):  
Nmr Spectroscopy ◽  
Ligand Exchange ◽  
H Nmr ◽  
Nmr Study ◽  
Exchange Kinetics ◽  
Monodentate Ligands ◽  
Kinetics Of

Abstract The ligand exchange on nonamethylimidodiphosphoramide (NIPA) complexes is found to be very slow comparatively to analogous monodentate ligands; the rates determined by 1H or 31P NMR spectroscopy are: k(25°C)=4.3 × 10-2 s-1; 31.6 s-1 • M-1; 3.7 × 104 S-1 • M-1 and 1.35 × 104 s-1 · M-1 for Mg2+, Ca2+, Sr2+ and Li+ cations respectively. For the Al3+, Ga3+, In3+ and Be2+ ions no exchange could be detected by 1H NMR spectroscopy up to 120 °C, indicating rates lower than about 10-3 s-1

scholarly journals GLUTARALDEHYDE FIXATION OF ISOLATED EUCARYOTIC NUCLEI

1973 ◽  
Vol 59 (2) ◽  
pp. 304-317 ◽  
Author(s):  
Donald E. Olins ◽  
Everline B. Wright
Keyword(s):  
Free Amino ◽  
Divalent Cations ◽  
Amino Groups ◽  
Chromatin Decondensation ◽  
Mole Percent ◽  
First Order ◽  
Close Proximity ◽  
Erythrocyte Nucleus ◽  
Fixation Reaction ◽  
Kinetics Of

Isolated chicken erythrocyte nuclei have been incubated with dilute concentrations of the bifunctional cross-linking agent glutaraldehyde (0–20 mM) in order to stabilize histone-histone interactions within the native nucleus. The kinetics of the disappearance of acid-soluble histones, free amino groups, and of individual histones have been observed to be pseudo first-order. Apparent first-order rate constants for the disappearance of individual histones correlate with the lysine mole percent of that fraction and follow the ranking, kapp: F1 > F2C > F2B ≥ F2A2, F2A1, F3. Histone polymers were observed to form very rapidly during the fixation reaction. Partial fractionation and amino acid analyses of these polymers support the view that they are composed principally of cross-linked (F2C)n molecules (where n = 2 to ∼8). The rate of glutaraldehyde reaction with free amino groups in histones is drastically reduced in solvents that promote chromatin decondensation (i.e., low ionic strengths in the absence of divalent cations) whereas the formation of cross-linked F2C polymers is less severely reduced. It is proposed that some F2C histones exist in close proximity within the isolated erythrocyte nucleus.

Kinetische und proteinchemische Untersuchungen am Succinyl-Papain / Kinetic and Chemical Investigations of Succinyl-Papain

1972 ◽  
Vol 27 (12) ◽  
pp. 1490-1497 ◽  
Author(s):  
H. G. Löffler ◽  
Fr. Schneider
Keyword(s):  
Free Amino ◽  
Succinic Anhydride ◽  
Kinetic Studies ◽  
Amino Groups ◽  
Native State ◽  
Limited Effect ◽  
X Ray ◽  
The Stability ◽  
Kinetics Of ◽  
Increased Activity

Kinetic studies of the reaction of papain with succinic anhydride demonstrate the reactivity of 10 amino groups, two of which are easily deacylated giving a stable succinylpapain with 3 free amino groups one of which is the free amino group of the terminal isoleucin. This modified enzyme has the tenfold solubility of papain between pH 5,9 - 9 and is a little more sensible to temperature than papain. Kinetic parameters of succinylpapain with N-Benzoyl-ʟ-arginine ethylester are: Km app =1,2 x 10-2 ᴍ( papain: 1,8 x 10-2 M) κcat=505 min-1 (papain: 475 min-1) at pH 6,2 and 37°C. The activity with the anionic substrate casein was 120 ± 10%, with the cationic protamine was 200 ± 20% of the activity of papain.Nitration of 17 ± 1 tyrosines of succinylpapain with tetranitromethane has only a limited effect on the activity of the enzyme. The kinetics of this reaction suggests the existence of three groups of tyrosines with different reactivity. The reaction of papain with tetranitromethane gives only insoluble, cross-linked products.Three of five present tryptophanes of papain and succinylpapain are oxidized by N-bromosuccinimide in the native state; in 8 ᴍ urea all residues are accessible. The esterase- and proteolytic activity of the oxidized enzyme decrease to less than 50% of controls while with benzoyl-ᴅ, ʟ-arginine-p-nitro-anilide there was observed an increased activity of about 250%. The stability of the enzyme drops considerably after oxidation of five tryptophane residues. Function and reactivity of the modified amino acids are discussed with regard to the results of the x-ray analysis of the enzyme

scholarly journals The reaction of 2,4,6-trinitrobenzenesulphonic acid with amino acids, peptides and proteins

1968 ◽  
Vol 108 (3) ◽  
pp. 383-391 ◽  
Author(s):  
R. B. Freedman ◽  
G. K. Radda
Keyword(s):  
Amino Acids ◽  
Glutamate Dehydrogenase ◽  
Free Amino ◽  
Reactive Species ◽  
Second Order ◽  
Amino Group ◽  
Exponential Rate ◽  
Amino Groups ◽  
Sh Group ◽  
Kinetics Of

1. The kinetics of the reaction of 2,4,6-trinitrobenzenesulphonic acid with various amino acids, peptides and proteins were studied by spectrophotometry. 2. The reaction of the α- and ∈-amino groups in simple amino acids was found to be second-order, and the unprotonated amino group was shown to be the reactive species. 3. By allowing for the concentration of unreactive −NH3+ group, intrinsic reactivities for the free amino groups were derived and shown to be correlated with the basicities. 4. The SH group of N-acetylcysteine was found to be more reactive to 2,4,6-trinitrobenzenesulphonic acid than most amino groups. 5. The reactions of insulin, chymotrypsinogen and ribonuclease with 2,4,6-trinitrobenzenesulphonic acid were analysed in terms of three exponential rate curves, each referring to one or more amino groups of the proteins. 6. The reaction of lysozyme with 2,4,6-trinitrobenzenesulphonic acid was found to display an acceleration effect. 7. From the reaction of 2,4,6-trinitrobenzenesulphonic acid with glutamate dehydrogenase at several enzyme concentrations, it was possible to discern two sets of amino groups of different reactivity, and to show that the number of groups in each set was decreased by aggregation of the enzyme.

Kinetics of the Dehydration of the β-Cages of Sodium Faujasites as Studied by H-NMR Spectroscopy

1992 ◽  
Vol 96 (4) ◽  
pp. 545-549 ◽  
Author(s):  
W. D. Basler ◽  
H. T. Lechert ◽  
D. Carboo ◽  
A. Knöchel
Keyword(s):  
Nmr Spectroscopy ◽  
H Nmr ◽  
Kinetics Of

Perhalogenated 2-pyridylporphyrin complexes: synthesis, self-coordinating aggregation properties, and catalytic studies

2002 ◽  
Vol 06 (01) ◽  
pp. 50-57 ◽  
Author(s):  
Júlio S. Rebouças ◽  
Maria Eliza M. D. de Carvalho ◽  
Ynara M. Idemori
Keyword(s):  
Nmr Spectroscopy ◽  
First Generation ◽  
Reduction Potential ◽  
Catalyst Concentration ◽  
Acid Base ◽  
H Nmr ◽  
Highly Active ◽  
Ph Dependent ◽  
Metal Insertion ◽  
Kinetics Of

The synthesis of 2, 3, 7, 8, 12, 13, 17, 18-octabromo-meso-tetrakis(2-pyridyl)porphyrin, H 2 Br 8 T 2 PyP , is described, including the comparison of four attempted methods for the demetallation of ZnBr 8 T 2 PyP . One of the methods represents a strategy of demetallation based on the acid-base properties of the macrocycle, the solvent-dependent kinetics of metal insertion into porphyrins and the pH -dependent solubility of the 2-pyridylporphyrin derivatives in water. Self-coordinating aggregation of ZnBr 8 T 2 PyP in non-coordinating solvents was verified by 1 H NMR spectroscopy. The Mn(III)/Mn(II) redox potential for MnBr 8 T 2 PyPCl is 0.38 V higher than the reduction potential measured for its first-generation analogue, MnT 2 PyPCl . Cyclohexane hydroxylation by iodosylbenzene was performed in CH3 CN catalyzed by MnBr 8 T 2 PyPCl and MnT 2 PyPCl . MnBr 8 T 2 PyPCl was highly active, even at low concentration (5 × 10−5 M ), but perhalogenation did not account for oxidative robustness. At such a low catalyst concentration, MnT 2 PyPCl exhibited no activity as inferred by comparison to blank experiments.

Synthesis of Oil-Soluble Aliphatic Acylated Epicatechin and their Free Radical Scavenging Activity

2013 ◽  
Vol 781-784 ◽  
pp. 1424-1429
Author(s):  
Zhe Gao ◽  
Yu Lei Pan ◽  
Ai Xia Qin ◽  
Xiao Hu Kang ◽  
Xi Yue Li ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Nmr Spectroscopy ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Free Radical Scavenging ◽  
Scavenging Activity ◽  
Tea Polyphenol ◽  
H Nmr ◽  
Better Than

A series of epicatechin derivatives, including 3-O-palmitoyl epicatechin, 3-O-myristoyl epicatechin, 3-O-lauroyl epicatechin, 3-O-decanoyl epicatechin and 3-O-octanoyl epicatechin, were prepared by the acylation method. Structures of these prepared products were characterized by LC/MS and 1H-NMR spectroscopy. Their antioxidant activity were assessed by the methods of DPPH and ABTS free radical scavenging. The results showed that aliphatic acyl epicatechin derivatives with varying aliphatic groups were synthesized by this method. The antioxidant activity of aliphatic acyl epicatechin derivatives were better than the oil-soluble tea polyphenol and BHT, equal to TBHQ.

Grafting of living poly(tetrahydrofuran) onto aminodendrimers

e-Polymers ◽  
2001 ◽  
Vol 1 (1) ◽  
Author(s):  
Leen M. Tanghe ◽  
Eric J. Goethals
Keyword(s):  
Nmr Spectroscopy ◽  
Molar Mass ◽  
Polymer Chains ◽  
Linear Polymer ◽  
Amino Groups ◽  
Hybrid Polymers ◽  
H Nmr ◽  
Primary Amino ◽  
Linear Poly ◽  
Grafting Degree

AbstractHybrid polymers consisting of poly(propyleneimine) dendrimers (AstramolTM) and linear poly(tetrahydrofuran) (polyTHF) were obtained by grafting living cationic polyTHF onto the dendrimer. By varying the mole ratio of polyTHF to dendrimer, either modified dendrimers, containing only a few linear polymer chains, or ‘superstar’ polymers, i.e. dendrimers containing a large number of polyTHF chains, were obtained. The average number of grafted chains per dendrimer unit, the grafting degree, could be estimated by means of 1H NMR spectroscopy. For polyTHF with molar mass of 2000 g/mol or lower, all primary amino functions of the dendrimers up to the 5th generation (32 primary amino functions) could be grafted. For polyTHF with molar mass of 4000 g/mol, the maximum grafting degree was lower than the number of primary amino groups available and decreased with increasing dendrimer generation.

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