Studies in the Physical Chemistry of Amino Acids, Peptides, and Related Substances. IX. The Dissociation Constants of Some Amino Acid Derivatives

Zief, Morris; Edsall, John T.

doi:10.1021/ja01290a040

Cited by 32 publications

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“…Indeed, the fact that 0-alkyl ureas are about 101° times a s basic as urea (21,22) must be attributed almost entirely t o the difference in resonance energies of the neutral molecules VI and VIII, since it is highly improbable that ions VII and I X have very different resonance energies. (The equilibrium between N-and 0-protonated forms of urea does not affect this argument.)…”

Section: Amidine Protonationmentioning

confidence: 99%

PROTONATION OF THE AMIDE GROUP: II. DICYCLOHEXYLUREA-O¹⁸

Stewart¹,

Muenster²

1961

Can. J. Chem.

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Dicyclohexylurea-018 containing 78% oxygen-18 has been prepared. The amide I and I1 bands in this molecule are located a t 1611 and 1575 cm-1 respectively compared to 1628 and 1575cm-1 in ordinary dicyclohexylurea(KBr disk).Thus the amide I band(carbony1 stretching) undergoes the expected shift to lower frequency on isotopic substitution. The p-toluenesulphonate salt of dicyclohexylurea has been prepared and been found to have a band a t 1669 cm-1 commonly attributed to carbonyl stretching in amide salts. This band, however, undergoes no isotopic shift and is clearly not due to a carbonyl stretching motion. This result casts doubt on the infrared evidence supporting N-protonation of amides.

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Section: Amidine Protonationmentioning

confidence: 99%

PROTONATION OF THE AMIDE GROUP: II. DICYCLOHEXYLUREA-O¹⁸

Stewart¹,

Muenster²

1961

Can. J. Chem.

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“…The reason for this is not known, but it is unlikely to be due to formation of the thiolactone, since this substance does not react appreciably with small amounts of silver ion at pH o 2. The carboxyl pK of N-formylcysteine does not appear to have been measured but is likely to be slightly below that of formylglycine, given as 3-4 by Zief & Edsall (1937). There is no complex formation between pH 6-5 and 9-0.…”

Section: Discussionmentioning

confidence: 93%

The estimation of thiols and disulphides by potentiometric titration with silver nitrate

Cecil

McPhee

1955

Biochemical Journal

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“…Second-order rate constants for the formation reaction of 3-chloro-5,5-dimetylhydantoin and 3-chloro-1hydroximethyl-5,5-dimethylhydantoin with HOCl Hydantoins + HOCl k 2 /M À1 s À1 (HOCl + RN À ) (7.5 ± 0.4) × 10 6 (10.1 ± 0.2) × 10 6 k 3 /M À1 s À1 (ClO À + RNH) (1.53 ± 0.08) × 10 5 (1.27 ± 0.02) × 10 5 pK 2 (RNH ⇄ RN À + H + ) 9.16 ± 0.08 9.37 ± 0.2 DMH, 5,5-dimethylhydantoin; MDMH, 1-hydroximethyl-5,5dimethylhydantoin. [32] 9.00 [58] 9.19 [59,60] 9.20 [61] H in position 1…”

Section: Hydrolysis Of N-chloro-hydantoins Formedmentioning

confidence: 99%

N-Chlorination rate of five-membered heterocyclic nitrogen compounds

Pastoriza

Antelo

Amoedo

et al. 2016

J. Phys. Org. Chem.

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aThe kinetics of N-chlorination reaction of pyrrolidine, pyrrolidone, succinimide, 5,5,-dimethyloxazolidine-2,4-dione, 5,5-dimethylhydantoin and 1-hydroximethyl-5,5-dimethylhydantoin with HOCl in aqueous solution were studied at 25°C, constant ionic strength and under isolation conditions in a wide pH range. The set of compounds studied in this paper is characterized by having different functional groups and the same cyclic structure, consisting of a five-member ring with a nitrogen atom in the ring, which is susceptible to be chlorinated. This series of compounds covers nine pK a units, and the kinetic studies allow us to know, like, the presence of an amino, amide or imide group modify the reactivity of nitrogenous compound.Experimental data were fitted to the first-order kinetic equation. All reactions were found to be of first order in both HOCl and nitrogenous compound concentration. Kinetics studies demonstrate that some of these compounds are hydrolyzed in alkaline medium. In each case, reaction mechanism in agreement with the experimental results is proposed. The results were compared with other compounds with similar cyclic structure (2-oxazolidinone and proline).

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Studies in the Physical Chemistry of Amino Acids, Peptides, and Related Substances. IX. The Dissociation Constants of Some Amino Acid Derivatives

Cited by 32 publications

References 0 publications

PROTONATION OF THE AMIDE GROUP: II. DICYCLOHEXYLUREA-O¹⁸

PROTONATION OF THE AMIDE GROUP: II. DICYCLOHEXYLUREA-O¹⁸

The estimation of thiols and disulphides by potentiometric titration with silver nitrate

N-Chlorination rate of five-membered heterocyclic nitrogen compounds

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Studies in the Physical Chemistry of Amino Acids, Peptides, and Related Substances. IX. The Dissociation Constants of Some Amino Acid Derivatives

Cited by 32 publications

References 0 publications

PROTONATION OF THE AMIDE GROUP: II. DICYCLOHEXYLUREA-O18

PROTONATION OF THE AMIDE GROUP: II. DICYCLOHEXYLUREA-O18

The estimation of thiols and disulphides by potentiometric titration with silver nitrate

N-Chlorination rate of five-membered heterocyclic nitrogen compounds

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Product

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PROTONATION OF THE AMIDE GROUP: II. DICYCLOHEXYLUREA-O¹⁸

PROTONATION OF THE AMIDE GROUP: II. DICYCLOHEXYLUREA-O¹⁸