1,721,069 research outputs found
One-pot synthesis of unsymmetrical aryl methylphosphinates by insertion of dichlorophosphines into the O-Me bond of anisoles
No full textThis letter describes a new one-pot method for the synthesis of unsymmetrical aryl methylphoshinates by insertion of phosphorus moiety into the O-Me bond of anisoles. These products are very difficult to obtain with other reported methods requiring several steps. © 2001 Elsevier Science Ltd. All rights reserved
Molecules
Full text linkMolecules (ISSN 1420-3049; CODEN: MOLEFW) is the leading international peer-reviewed open access journal of chemistry. Molecules is published semi-monthly online by MDPI. Indexed by the Science Citation Index Expanded (Web of Science), MEDLINE (PubMed), Scopus and other databases.Impact Factor: 3.098 (2017) ; 5-Year Impact Factor: 3.268 (2017
Formation and stability of zwitterionic complexes between nitrobenzofuroxans and amines
No full textSpectroscopic and kinetic investigations on the reactions between 4,6-dinitrobenzofuroxan, 4-nitrobenzofuroxan and tertiary and secondary amines (i.e. 1,4-diazabicyclo[2.2.2]octane, quinuclidine, 1,8-diazabicyclo[5.4.0]undec-7-ene and piperidine) indicate the formation of zwitterionic or anionic complexes. The equilibrium between zwitterionic and anionic complexes is discussed (for reaction with piperidine) on the basis of 1H NMR spectral data, which indicate the presence of anionic complexes arising from the zwitterionic complex by a fast proton departure. The stability and the rate of formation of title complexes are discussed and compared to similar reactions of 1,3,5-trinitrobenzene
Kinetics and mechanism of condensation reactions of thiobenzamides and N-substituted thioureas
No full textThe condensation reaction of thiobenzamides and of N-substituted thioureas in dimethyl sulfoxide or in methanol, in the presence of the mixture DMSO–H+–X− (X = Cl, Br) produces 1,2,4-thiadiazole derivatives. Kinetic investigation emphasizes the importance of the presence of dimethyl sulfoxide, of halide ions and of an acidic catalyst. For reactions of thiobenzamide, the bromide ion increases the reaction rate 150 times more than the chloride ion. The presence of electron-donating groups on the starting thioamidic group enhances the reactivity. Reported data indicate that the mixture DMSO–H+–X− produces a positive halogen species. The proposed mechanism involves the formation of the N-halogenated thioamides (or N-substituted thioureas) in the rate-determining step. The reactivity of thionicotinamide S-oxide is also reported and discussed. © 2002 The Royal Society of Chemistry
Kinetics of formation of zwitterionic complexes between 1,3,5-trinitrobenzene and diazabicyclo derivatives
No full textThe title reactions are a simple model of nucleophilic attack of tertiary nitrogen on aromatic sp carbons activated by the presence of nitro groups. The formation of the zwitterionic complexes is mildly affected by solvent changes and by addition of tetraethylammonium chloride. The reactivity of 1,4-diazabicyclo[2.2.2]octane, quinuclidine and 1,8-diazabicyclo[5.4.0]undec-7-ene is compared with that of primary and secondary amines
New feature of Friedel-Crafts phosphonation of anisoles: Unexpected in situ methylphosphorylation reaction
No full textAnisoles 1, reacting with AlCl3 and PCl3 with appropriate reagent ratios, give, in good yields, the corresponding diaryl methylphosphonates 2 or the methylphoshinates 3b,c and the methylphosphine oxides 4b,c. This unexpected in situ methylphosphorylation explains the reported limited and conflicting results to obtain methoxy-substituted arylphosphonous dichloride with the same reagents. A suggested mechanism is also reported
A one-pot synthesis of 1-substituted cyclic phosphine sulfides by simultaneous addition of bis- and mono-grignard reagents to a new efficient phosphorus donating reagent
No full textThe synthesis of the reported cyclic phosphine sulfides (4, 5, 6) is carried out in good yields in a one-pot reaction with simultaneous addition of the three reagents (1, BrMgCH2(CH2)(n)CH2MgBr, RMgBr) and final treatment with sulfur. The new phosphorus donating reagent benzothiadiphosphole 1 is an inexpensive, facile to prepare, and air-insensitive solid
Particulate matter in urban area of Bologna (Italy): Data dissection
No full textParticulate matter arising from usual activities in urban area is generally indicated as dangerous pollutant. We are reporting some data obtained by aerosol spectrometer which allowed us to know the concentration of three classes of particulate matter (PM10, PM2,5, PM1). The comparison of data recorded in summer and in winter and in some days presenting a particular social situation or in particular weather conditions, indicates the possibility to discriminate the particulate matter amount arising from traffic and arising from other human activities, mainly from heating house. This possibility is due to the values of ratio of the amount of particulate matter: PM10/PM2,5 and PM10/PM1 ratio are near to 1 value for PM deriving from heating house and they are much higher for PM deriving from traffic. The tentative evaluation of the relative importance of the two main sources of particulate matter is about half for one, but the emission of particulate matter of heating house is largely predominant in the presence of some meteorological events such as thermal inversion. The fashion regarding heating house by firewood heaters, without any check or abatement, aggravates the hazards associated to the home heating. However, the pollution from traffic regards the whole year, while the pollution from heating house is on 5 or 6 months only. Consequently, the relative importance of the two sources in releasing PM10 in air in a year results in four times higher for traffic than for home heating
4,6-dinitro-7-(Thiazol-2-ylamino)benzo[c][1,2,5] oxadiazole 1-oxide
Full text link4,6-Dinitro-7-(thiazol-2-ylamino)benzo[c][1,2,5]oxadiazole 1-oxide was synthesized by a SN Ar reaction between 7-chloro-4,6-dinitrobenzofuroxan and 2-aminothiazole. The structure of the newly synthesized compound (45% yield) was elucidated based on1 H-NMR,13 C-NMR, NOESY-1D, ESI-MS, UV-Vis, and FT-IR techniques
Kinetics and mechanism of reactions between 2,4,6-trinitrofluorobenzene and alcohols
No full textThe kinetics of formation of some ethers from alcohols and 2,4,6-trinitrofluorobenzene were studied under first order conditions ([ROH]o > [TNFB]o). In CCl4, k (in dm3 s-1 mol-1) values are increased on increasing the values of the initial concentrations of the alcohols. This anomalous kinetic behaviour parallels that of reactions between amines and activated aromatic fluoro derivatives. The presence of a substrate-alcohol interaction which precedes the substitution process explains the kinetic behaviour of the alcohols
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