Oxygen-18 exchange accompanying the basic hydrolysis of primary, secondary, and tertiary toluamides. 2. The importance of amine leaving abilities from the anionic tetrahedral intermediate

1990 ◽  
Vol 112 (23) ◽  
pp. 8507-8514 ◽  
Author(s):  
H. Slebocka-Tilk ◽  
A. J. Bennet ◽  
J. W. Keillor ◽  
R. S. Brown ◽  
J. Peter Guthrie ◽  
...  
Keyword(s):  
Tetrahedral Intermediate ◽  
Basic Hydrolysis ◽  
Hydrolysis Of

The Importance of Conformation of the Tetrahedral Intermediate in the Hydrolysis of Amides. Selective Cleavage of the Tetrahedral Intermediate Controlled by Orbital Orientation

1973 ◽  
Vol 51 (10) ◽  
pp. 1665-1669 ◽  
Author(s):  
Pierre Deslongchamps ◽  
Claude Lebreux ◽  
Roland Taillefer
Keyword(s):  
Experimental Evidence ◽  
Lone Pair ◽  
Tetrahedral Intermediate ◽  
Basic Hydrolysis ◽  
Hydrolysis Of ◽  
Orbital Orientation

The basic hydrolysis of N-disubstituted imidate salts proceeds via a hemi-orthoamide tetrahedral intermediate which can in principle give amide–alcohol or ester–amine products. Experimental evidence has been obtained which shows that the specific conformation of the tetrahedral intermediate determines products formation and it is further suggested that the orientation of the lone pair orbitals of the heteroatoms governs this remarkable selective decomposition.

Basic hydrolysis of some N-phenylcarbamates and basic methanolysis of some N-phenylacetamides containing an ortho nitro substituent

1984 ◽  
Vol 37 (10) ◽  
pp. 2005
Author(s):  
TJ Broxton
Keyword(s):  
Induction Period ◽  
Nitro Group ◽  
Resonance Effect ◽  
Kinetic Studies ◽  
Bond Breaking ◽  
Hydroxide Ion ◽  
Tetrahedral Intermediate ◽  
Group Reaction ◽  
Basic Hydrolysis ◽  
Hydrolysis Of

Kinetic studies of the basic methanolysis of N-(2-nitropheny1)acetamides indicate that unlike the 4-nitro isomer, no change of mechanism occurs on inclusion of an N-methyl group. Reaction occurs with rate-determining C-N bond breaking for both the N-H and N-methyl compounds. Basic hydrolysis of some methyl N-(2-nitropheny1)carbamates occurred by the BAC2 mechanism and the tetrahedral intermediate formed during the hydrolysis decomposed with preferential C-O bond breaking. This is in contrast to the basic hydrolysis of methyl N-methyl-N-4-nitrophenyl- carbamate, which has previously been shown to occur with preferential C-N bond breaking. For the hydrolysis of methyl N-methyl-N-(2-nitrophenyl)carbamate, an induction period in amine production was detected at 0.45 M hydroxide ion. This was interpreted to mean that the tetrahedral intermediate breaks down by loss of methoxide ion. At 0.93 M hydroxide ion, however, no induction period in amine production was observed. The possibility of reaction through a dianionic intermediate was raised to explain this observation. The amide ion (2-NO2C6H4NMe-) is a poorer leaving group than its 4-nitro isomer. This is explained by steric crowding in the 2-nitro compound, resulting in twisting of the nitro group out of the plane of the benzene ring and a consequent reduction in the electron-withdrawing resonance effect of the 2-nitro group compared to the 4-nitro group.

The Hydrolysis of Imidate Salts. Stereoelectronic Control in the Cleavage of the Hemiorthoamide Tetrahedral Intermediate

1975 ◽  
Vol 53 (18) ◽  
pp. 2791-2807 ◽  
Author(s):  
Pierre Deslongchamps ◽  
Serge Dubé ◽  
Claude Lebreux ◽  
Dennis R. Patterson ◽  
Roland J. Taillefer
Keyword(s):  
Alkyl Group ◽  
Lone Pair ◽  
The Other ◽  
Tetrahedral Intermediate ◽  
Hydrolysis Products ◽  
Anti Conformation ◽  
Stereoelectronic Control ◽  
Basic Hydrolysis ◽  
Hydrolysis Of ◽  
Nitrogen Bond

A new stereoelectronic theory for the cleavage of the tetrahedral intermediate (hemiorthoamide) in the hydrolysis of amides is presented. In this new theory, the precise conformation of the tetrahedral intermediate controls the nature of the hydrolysis products. It is postulated that the breakdown of the tetrahedral intermediate depends upon the orientation of the lone pair orbitals of the heteroatoms. Specific cleavage of a carbon–oxygen or a carbon–nitrogen bond in any conformer is allowed only if the other heteroatoms (oxygen and nitrogen) each have an orbital oriented antiperiplanar to the leaving O-alkyl or N-alkyl group. Experimentally, a study of the basic hydrolysis of a variety of N,N-dialkylated imidate salts having either a syn or an anti conformation demonstrates clearly that there is a stereoelectronic control in the cleavage of the hemiorthoamide.

Micellar catalysis of organic reactions. XII. Basic hydrolysis of some alkyl and aryl N-(4-Nitrophenyl)carbamates

1984 ◽  
Vol 37 (1) ◽  
pp. 47 ◽  
Author(s):  
TJ Broxton
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Kinetic Studies ◽  
Micellar Catalysis ◽  
Organic Reactions ◽  
Bond Breaking ◽  
Tetrahedral Intermediate ◽  
Stable Product ◽  
Methyl Derivatives ◽  
Basic Hydrolysis ◽  
Hydrolysis Of

The basic hydrolysis of a number of alkyl and aryl N-(4-nitrophenyl)carbamates in the presence and absence of micelles of cetyltrimethylammonium bromide (ctab) are reported. In water the stable product at 26�C was N-(4-nitrophenyl)carbamate ion (3). At higher temperatures this carbamate ion slowly decomposed to 4-nitroaniline. In ctab the decarboxylation of the N-(4-nitrophenyl)carbamate ion was strongly catalysed (× 45) and thus the observed final product even at 26�C was 4-nitroaniline. Kinetic studies in water and in ctab were consistent with decomposition of the methyl carbamate (la) by a BAC2 mechanism and the 2,2,2-trifluoroethyl carbamate (lc) by an E1cB mechanism. The extent of ionization of the substrate carbamates to nitranion (4) was enhanced in ctab as was the rate of spontaneous decomposition of the nitranion. This is in contrast to other E1cB reactions reported in the literature, for which the rate of spontaneous decomposition of the carbanion was inhibited by ctab. For compounds reacting by the BAC2 mechanism, the tetrahedral intermediate (2) partitioned in favour of C-OR bond breaking rather than C-N bond breaking observed previously for some N-methyl derivatives.

Basic hydrolysis of some alkyl and phenyl N-Aryl-N-methylcarbamates

1983 ◽  
Vol 36 (11) ◽  
pp. 2203 ◽  
Author(s):  
TJ Broxton
Keyword(s):  
Rate Constants ◽  
Cetyltrimethylammonium Bromide ◽  
Ester Hydrolysis ◽  
Micellar Catalysis ◽  
Bond Breaking ◽  
Methyl Ethyl ◽  
Hydroxide Ion ◽  
Tetrahedral Intermediate ◽  
Basic Hydrolysis ◽  
Hydrolysis Of

Rate constants for the basic hydrolysis of methyl, ethyl and phenyl N-aryl-N-methylcarbamates in the presence and absence of micelles of cetyltrimethylammonium bromide are reported. Hammett plots for the methyl and ethyl carbamates were curved, and this is explained by consideration of the competition between C-N and C-OR bond breaking for decomposition of the tetrahedral intermediate. In one case (p-nitro-substituted), rate-determining formation of the tetrahedral intermediate is suggested, whereas for other compounds rate-determining C-N bond breaking or C-OR bond breaking is proposed. Micellar catalysis for each of the reactions is reported, and large catalysis (× 50) was observed for compounds where C-N bond breaking was kinetically significant. This is compared with results in the literature for amide and ester hydrolysis. Whereas, for ester hydrolysis, loss of alkoxide ion from the tetrahedral intermediate is favoured over loss of hydroxide ion, in carbamate hydrolysis, loss of hydroxide ion is favoured. A possible reason for this reversal of nucleofugicity of OH- and OR- is proposed.

A FACILE SYNTHESIS AND REACTIONS OF AMINO SELENOLO[2,3-b]PYRIDINE CARBOXYLATE

2015 ◽  
Vol 12 (1) ◽  
pp. 3910-3918 ◽  
Author(s):  
Dr Remon M Zaki ◽  
Prof Adel M. Kamal El-Dean ◽  
Dr Nermin A Marzouk ◽  
Prof Jehan A Micky ◽  
Mrs Rasha H Ahmed
Keyword(s):  
Biological Activity ◽  
Carbonyl Compounds ◽  
Mass Spectra ◽  
The Other ◽  
Pyridine Derivatives ◽  
Facile Synthesis ◽  
High Biological Activity ◽  
Basic Hydrolysis ◽  
Pyridine Carboxylate ◽  
Hydrolysis Of

 Incorporating selenium metal bonded to the pyridine nucleus was achieved by the reaction of selenium metal with 2-chloropyridine carbonitrile 1 in the presence of sodium borohydride as reducing agent. The resulting non isolated selanyl sodium salt was subjected to react with various α-halogenated carbonyl compounds to afford the selenyl pyridine derivatives 3a-f  which compounds 3a-d underwent Thorpe-Ziegler cyclization to give 1-amino-2-substitutedselenolo[2,3-b]pyridine compounds 4a-d, while the other compounds 3e,f failed to be cyclized. Basic hydrolysis of amino selenolo[2,3-b]pyridine carboxylate 4a followed by decarboxylation furnished the corresponding amino selenolopyridine compound 6 which was used as a versatile precursor for synthesis of other heterocyclic compound 7-16. All the newly synthesized compounds were established by elemental and spectral analysis (IR, 1H NMR) in addition to mass spectra for some of them hoping these compounds afforded high biological activity.

ChemInform Abstract: THE UNUSUALLY MILD AND FACILE BASIC HYDROLYSIS OF N-NITROSO-2-(METHYLAMINO)ACETONITRILE

1977 ◽  
Vol 8 (9) ◽  
pp. no-no
Author(s):  
S. K. CHANG ◽  
G. W. HARRINGTON ◽  
H. S. VEALE ◽  
D. SWERN
Keyword(s):  
Basic Hydrolysis ◽  
Hydrolysis Of
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