Cyclization Kinetics of Nondiluted Bond Fluctuation Chains

2002 ◽  
Vol 35 (14) ◽  
pp. 5681-5687 ◽  
Author(s):  
Ana M. Rubio ◽  
Marcos Pita ◽  
Juan J. Freire
Keyword(s):  
Cyclization Kinetics ◽  
Bond Fluctuation ◽  
Kinetics Of

Kinetics and mechanism of cyclization of N-(2-methoxycarbonylphenyl)-N’-methylsulphonamide to 3-methyl-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide

1991 ◽  
Vol 56 (8) ◽  
pp. 1701-1710 ◽  
Author(s):  
Jaromír Kaválek ◽  
Vladimír Macháček ◽  
Miloš Sedlák ◽  
Vojeslav Štěrba
Keyword(s):  
Potassium Hydroxide ◽  
Acid Catalysis ◽  
Potassium Hydroxide Solution ◽  
Hydroxide Solution ◽  
General Base ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Cyclization Kinetics ◽  
Rate Limiting ◽  
Kinetics Of

The cyclization kinetics of N-(2-methylcarbonylphenyl)-N’-methylsulfonamide (IIb) into 3-methyl-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide (Ib) has been studied in ethanolamine, morpholine, and butylamine buffers and in potassium hydroxide solution. The cyclization is subject to general base and general acid catalysis. The value of the Bronsted coefficient β is about 0.1, which indicates that splitting off of the proton from negatively charged tetrahedral intermediate represents the rate-limiting and thermodynamically favourable step. In the solutions of potassium hydroxide the cyclization of dianion of the starting ester IIb probably becomes the rate-limiting step.

Cyclization kinetics of poly(acrylonitrile)

Carbon ◽  
1996 ◽  
Vol 34 (5) ◽  
pp. 561-566 ◽  
Author(s):  
L.A. Beltz ◽  
R.R. Gustafson
Keyword(s):  
Cyclization Kinetics ◽  
Kinetics Of ◽  
Poly Acrylonitrile

Cyclization Kinetics of N-(β-Haloalkyl)benzenesulfonamides

1966 ◽  
Vol 31 (2) ◽  
pp. 568-575 ◽  
Author(s):  
Walter J. Gensler ◽  
Barry A. Brooks
Keyword(s):  
Cyclization Kinetics ◽  
Kinetics Of

Cyclization kinetics and mechanism of N-benzoyl-N'-(1,2-dimethyl-3-oxo-1-butenyl)thiourea

1983 ◽  
Vol 48 (2) ◽  
pp. 578-585 ◽  
Author(s):  
Jaromír Kaválek ◽  
Tomáš Potěšil ◽  
Vojeslav Štěrba
Keyword(s):  
Hydrochloric Acid ◽  
Secondary Amines ◽  
Tertiary Amines ◽  
Cyclization Product ◽  
Ph Values ◽  
Hydroxyl Ion ◽  
Primary And Secondary Amines ◽  
Acids And Bases ◽  
Cyclization Kinetics ◽  
Kinetics Of

Cyclization kinetics of N-benzoyl-N'-(1,2-dimethyl-3-oxo-1-butenyl)thiourea have been studied in aqueous and methanolic solutions of acids and bases. In all cases the cyclization product is 4,5,6-trimethyl-2,5-dihydro-2-thioxopyrimidine or its protonated or deprotonated forms. In dilute methanolic and aqueous hydrochloric acid the substrate reacts in its monoprotonated form. The cyclization in basic media is catalyzed by methoxide or hydroxyl ion and also by primary and secondary amines at such pH values where the catalysis by lyate ion is practically insignificant. Tertiary amines and acetate ion do not catalyze the cyclization.

scholarly journals Reactive conformations and non-Markovian cyclization kinetics of a Rouse polymer

2013 ◽  
Vol 138 (9) ◽  
pp. 094908 ◽  
Author(s):  
T. Guérin ◽  
O. Bénichou ◽  
R. Voituriez
Keyword(s):  
Cyclization Kinetics ◽  
Kinetics Of

On the kinetics of nematic ordering in solutions of semiflexible macromolecules: a Monte Carlo simulation

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Mikhail R. Stukan ◽  
Viktor A. Ivanov ◽  
Marcus Müller ◽  
Wolfgang Paul ◽  
Kurt Binder
Keyword(s):  
Monte Carlo ◽  
Liquid Crystalline ◽  
Persistence Length ◽  
Grand Canonical Monte Carlo ◽  
Solvent Quality ◽  
Nematic Ordering ◽  
Bond Fluctuation ◽  
Kinetics Of ◽  
Grand Canonical ◽  
Fluctuation Model

Abstract The occurrence of nematic liquid-crystalline ordering in semidilute and concentrated solutions of semiflexible macromolecules has been studied by means of grand canonical Monte Carlo computer simulations using the bond fluctuation model and the configurational bias scheme. Chain length was equal to 20 monomer units, while the persistence length was about 5 monomer units. We used an intramolecular stiffness potential depending on the angle between successive bonds along the chain and on the bond length, and an attractive interaction between monomer units to model variable solvent quality. We have monitored the processes of appearance and destruction of monodomain and multidomain nematic configurations. Our findings are that the first stages of both the ordering and disordering processes occur upon sufficient oversaturation through the spinodal ordering scenario. Possible screening of nucleation processes and the applicability of our model to real kinetics are discussed. Results of our simulations are visualized in six movies.

Kinetics of Cyclization of Methyl S-(2,4,6-Trinitrophenyl)mercaptoacetate to 2-Methoxycarbonyl-5,7-dinitrobenzo[d]thiazol-3-oxide

1997 ◽  
Vol 62 (9) ◽  
pp. 1429-1445 ◽  
Author(s):  
Marek Janík ◽  
Vladimír Macháček ◽  
Oldřich Pytela
Keyword(s):  
Rate Equation ◽  
Reaction Order ◽  
Gradual Decrease ◽  
Reaction Paths ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Cyclization Kinetics ◽  
The Given ◽  
Rate Limiting ◽  
Kinetics Of

The cyclization kinetics of methyl S-(2,4,6-trinitrophenyl)mercaptoacetate to 2-methoxycarbonyl-5,7-dinitrobenzo[d]thiazol-3-oxide have been studied in acetate, methoxyacetate or N-methylmorpholine buffers. In the acetate and methoxyacetate buffers, the cyclization obeys the rate equation v = [SH](k'MeO[CH3O-] + k'B[B-] + k'B,MeO[B-][CH3O-]) and goes by two reaction paths differing in the order of their reaction steps, the splitting off of the proton from C-H group being the rate-limiting step in either path. In the N-methylmorpholine buffers, increasing concentration of the base results in gradual decrease of reaction order in the base and change in the rate-limiting step of cyclization. Methyl S-(2,4-dinitrophenyl)mercaptoacetate undergoes cyclization neither in the given buffers nor in methoxide solution.

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