- Facile N-nitrosation of secondary amines using poly(N,N'-dibromo-Nethylene- benzene-1,3-disulfonamide) and N,N,N′,N′-tetrabromobenzene-1,3- disulfonamide/NaNO2 under mild conditions
-
In this research project, a combination of poly(N,N′-dibromo-N- ethylene-benzene-1,3-disulfonamide) [PBBS] and/or (N,N,N′,N′- tetrabromobenzene-1,3-disulfonamide) [TBBDA] with sodium nitrite in the presence of wet SiO2 (50% w/w) was used as an efficient nitrosating agent for the conversion of secondary amines to their corresponding nitroso compounds. N-Nitrosation reaction has been performed in dichloromethane at room temperature under mild and heterogeneous conditions. The reaction is operationally simple and corresponding products were achieved in good to excellent yields.
- Ghorbani-Vaghei, Ramin,Shiri, Lotfi,Ghorbani-Choghamarani, Arash
-
p. 204 - 208
(2013/07/26)
-
- N-nitrosation of secondary amines using supported perchloric acid on silica gel and stereoselectivity study of nitrosated products
-
N-Nitrosation of different types of secondary amines has been proceeded using supported perchloric acid on silica gel and sodiume nitrite under heterogeneous conditions. The operational system is simple and high pure products can be easily isolated with good to high yields.
- Goudarziafshar, Hamid,Ghorbani-Choghamarani, Arash,Hadian, Laila
-
p. 1272 - 1276
(2014/04/03)
-
- Ph3P/Br2/n-Bu4NNO2 as an efficient system for the preparation of N-nitrosamines and azides
-
The combination PPh3/Br2/n-Bu4NNO2 was developed as a new reagent system for the efficient preparation of N-nitrosamines and azides from the corresponding amines and hydrazine derivatives, respectively, at 0 °C to room temperature, in excellent yields.
- Iranpoor, Nasser,Firouzabadi, Habib,Nowrouzi, Najmeh
-
p. 4242 - 4244
(2008/09/20)
-
- Efficient procedure for chemoselective N-nitrosation of secondary amines with trichloromelamine-NaNO2
-
A combination of trichloromelamine and sodium nitrite in the presence of wet silica gel was used as an effective nitrosating agent for the transformation of secondary amines into the corresponding N-nitroso derivatives under mild and heterogeneous conditions in good to excellent yields.
- Bamoniri,Zolfigol,Mirjalili,Fallah
-
p. 1393 - 1396
(2008/03/27)
-
- Molybdate sulfuric acid/NaNO2: A novel heterogeneous system for the N-nitrosation of secondary amines under mild conditions
-
Wet molybdate sulfuric acid (=dioxo[bis(sulfato-κO)]molybdenum; MSA), a new solid acid, can be used in combination with sodium nitrite (NaNO 2) to transform a variety of secondary amines to the corresponding N-nitroso compounds under mild, heterogeneous conditions (Table). The process has several advantages: the reagents are inexpensive and non-hazardous, the reaction is clean, fast, and high-yielding, and MSA can be readily removed by filtration and re-used (after treatment with HCl) without loss of activity. Further, only N-nitrosation was observed, but no C- or O-nitrosation.
- Montazerozohori, Morteza,Karami, Bahador
-
p. 2922 - 2926
(2007/10/03)
-
- Alumina-methanesulfonic acid (AMA)/NaNO2 as an efficient procedure for the chemoselectivite N-nitrosation of secondary amines
-
A combination of alumina/methanesulfonic acid (AMA) and sodium nitrite was used as an effective nitrosating agent for the nitrosation of secondary amines under mild and heterogeneous conditions in good to excellent yields. Copyright Taylor & Francis Group, LLC.
- Niknam, Khodabakhsh,Zolfigol, Mohammad Ali
-
p. 2311 - 2319
(2007/10/03)
-
- The use of Nafion-H/NaNO2 as an efficient procedure for the chemoselective N-nitrosation of secondary amines under mild and heterogeneous conditions
-
A combination of Nafion-H and sodium nitrite in the presence of wet SiO2 was used as an effective agent for the N-nitrosation of secondary amines under mild and heterogeneous conditions in good to excellent yields.
- Zolfigol, Mohammad Ali,Habibi, Davood,Mirjalili, BiBi Fatemeh,Bamoniri, Abdolhamid
-
p. 3345 - 3349
(2007/10/03)
-
- Trichloroisocyanuric acid/NaNo2 as a novel heterogeneous system for the N-nitrosation of N,N-dialkylamines under mild conditions
-
A combination of trichloroisocyanuric acid and sodium nitrite in the presence of wet SiO2 was used as an effective nitrosating agent for the nitrosation of N,N-dialkyl amines to their corresponding nitroso derivatives under mild and heterogeneous conditions in moderate to excellent yields.
- Zolfigol, Mohammad Ali,Choghamarani, Arash Ghorbani,Hazarkhani, Hassan
-
p. 1002 - 1004
(2007/10/03)
-
- Silica sulfuric acid/NaNO2 as a novel heterogeneous system for the chemoselective N-nitrosation of secondary amines under mild conditions
-
Neat chlorosulfonic acid reacts with silica gel to give silica sulfuric acid in which sulfuric acid is immobilized on the surface of silica gel via a covalent bond. A combination of silica sulfuric acid and sodium nitrite in the presence of wet SiO2 was used as an effective nitrosating agent for the nitrosation of secondary amines to their corresponding nitroso derivatives under mild and heterogeneous conditions in excellent yields.
- Zolfigol, Mohammad Ali,Bamoniri, Abdolhamid
-
p. 1621 - 1624
(2007/10/03)
-
- Differences in the activity of neutral and ionized β-cyclodextrin on the nitrosation of amines by phenylpropyl nitrites
-
The influence of β-cyclodextrin (β-CD) on the base-catalyzed hydrolysis reaction of 1-phenyl-1-propyl, 2-phenyl-1propyl and 3-phenyl-1-propyl nitrites and on the nitrosation of pyrrolidine, piperidine and N-methylcyclohexylamine by the aforementioned alkyl nitrites (RONO) is studied in aqueous buffers of the amines and in an alkaline medium with [OH-] = 0.20 M. The hydrolysis reaction is catalyzed by the presence of β-CD owing to the formation of reactive 1:1 inclusion complexes between the alkyl nitrite and the ionized β-CD; the addition of potential inhibitors, such as dodecyltrimethylammonium bromide monomers, accelerates the reaction even more. The effect is quite significant in the case of 1-phenyl-1-propyl nitrite and is viewed as a case of allostery. In the presence of neutral β-CD, the nitrosation by 1-phenyl-1-propyl nitrite, either of pyrrolidine or piperidine, is inhibited by β-CD addition; however, the nitrosation reaction of piperidine by 2-phenyl-1-propyl nitrite is catalyzed (passing through a maximum) by β-CD, whereas the nitrosation of pyrrolidine promoted by 3-phenyl-1-propyl nitrite exhibits practically no change upon β-CD addition. In alkaline media (containing ionized β-CD) the nitrosation of pyrrolidine by 1-phenyl-1-propyl nitrite is inhibited by the presence of β-CD; in contrast, the nitrosation of both piperidine and N-methylcyclohexylamine is catalyzed in all cases, but the degree of catalysis depends not only on the alkyl nitrite structure, but also on the type and concentration of the amine. Kinetic results are quantitatively interpreted on the basis of the proposed reaction mechanism in each case, and the kinetic rate constants of the different steps are determined. Comparison of the results obtained in aqueous alkaline media and in aqueous buffers of the amines themselves allows us to establish important characteristics of the transition state of the reaction.
- Iglesias
-
p. 1025 - 1035
(2007/10/03)
-
- Cyclodextrins as enzyme models in nitrosation and in acid-base- catalyzed reactions of alkyl nitrites
-
The widely studied cyclodextrin-mediated reactions of esters but not those of alkyl nitrites, together with the marked differences between the chemistry of esters and alkyl nitrites, prompted us to investigate the influence of β-cyclodextrin (β-CD) on the reactions of alkyl nitrites. Due to the particular characteristics of alkyl nitrite reactions, the system β- cyclodextrin-alkyl nitrites allows us to explore cyclodextrin's behavior under several experimental conditions, contrary to the case of esters. Therefore, general acid-base-catalyzed hydrolysis and nitrosation of amines by alkyl nitrites are studied. Alkyl nitrites of a particular structure have been chosen to clearly evidence the mimicry of enzyme catalysis by β-CD. Addition of β-CD strongly inhibits the acid hydrolysis of alkyl nitrites (a very fast reaction in water), except in the case of ethoxyethyl nitrite, where no effect is detected. The retardation of the reaction is attributed to a separation of the reagents: β-CD and alkyl nitrites form host-guest 1:1 inclusion complexes, but simple cations, such as H3O+ in the present case, did not prove to include into the β-CD cavity. In fact, at constant β-CD concentrations, addition of dodecyltrimethylammonium bromide monomers (DTABr), which strongly compete with alkyl nitrites for the hydrophobic β- CD cavity and, thus, expel the alkyl nitrites, catalyzes the reaction. On the contrary, in alkaline medium, when a secondary hydroxy group of β-CD is ionized, addition of β-CD to the reaction medium strongly catalyzes the basic hydrolysis of alkyl nitrites (an extremely slow reaction in water). The degree of catalysis depends on the alkyl nitrite structure, varying from a factor higher than 100 in the case of 3-phenyl-1-propyl nitrite, to 0 (no reaction is observed) in the case of 2-phenyl-2-propyl nitrite. The effective molarities calculated for the catalysis evidence a base-catalyzed mechanism for the reaction. The strong catalysis observed with 1-phenyl-1-propyl nitrite upon the addition of DTABr is indicative of an example of allosteric activation. Finally, the nitrosation of pyrrolidine, piperidine, and cyclohexylamine by ethoxyethyl nitrite is slightly catalyzed by the presence of β-cyclodextrin. The degree of the observed catalysis depends on both the amine concentration and the structure.
- Iglesias, Emilia
-
p. 13057 - 13069
(2007/10/03)
-
- Lack of detectable DNA alkylation for bromhexine in man
-
It is known that in vitro incubation of the expectorant drug bromhexine (N-methyl-N-cyclohexyl-(2-amino-3,5-dibromobenzyl)-ammonium hydrochloride) with nitrite yields methylcyclohexyl nitrosamine (NMCA). NMCA is capable of methylating DNA when administered to rats. In vivo tests with bromhexine have also demonstrated that the drug methylates DNA when it is orally administered in the presence of sodium nitrate, presumably due to the intragastric formation of NMCA. In this study the potential of bromhexine to methylate nucleic acids in man, under physiological conditions, has been investigated. 20 volunteers were orally administered on each of three successive days 48 mg of bromhexine hydrochloride, labelled with three deuterium atoms in the N-methyl group. Urine was collected before treatment and subsequent to the last dose, and analysed by GC-MS for d0- and d3-7-methylguanine. 7-Methylguanine is naturally occurring in urine owing to the turnover of t-RNA of which it is a minor constituent. It is also a repair product from nucleic acid methylated by carcinogens, which is known to be excreted unmetabolised largely within 24 h of the methylation process. Unlabelled 7-methylguanine was present at levels of 7.36 ± 2.43 mg/d in control urine and 6.12 ± 2.36 mg/d in treated urine, in a cord with previously published values. The excretion of isotopically labelled 7-methylguanine averaged 0.43 ± 0.077% of the unlabelled concentration for control urines and 0.44 ± 0.066% for treated urines, i.e. no d3-7-methylguanine could be detected following the drug treatment. The observed signals were largely accounted for by the naturally occurring isotopes 13C and 15N. This determines the detection limit of the assay which is able to detect an excess amount of d3-7-methylguanine of 0.15% of d0-7-methylguanine. With these methods no methylation of DNA by bromhexine under in vivo conditions could be detected.
- Farmer,Parry,Franke,Schmid
-
p. 1351 - 1354
(2007/10/02)
-