mohamed besheesh - Academia.edu (original) (raw)
Papers by mohamed besheesh
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Journal of Fluorine Chemistry, Sep 1, 1991
Iron oxide is a mineral compound that shows different polymorphic forms, including hematite (α-Fe... more Iron oxide is a mineral compound that shows different polymorphic forms, including hematite (α-Fe 2 O 3), magnetite (Fe 3 O 4) and maghemite (γ-Fe 2 O 3). Solid propulsion technology nanoparticulate materials, such as hematite and maghemite, exhibit high performance on thermal decomposition of ammonium perchlorate. The enhanced catalytic effect of metallic iron oxide nanoparticles is attributed to their particle size, more active sites and high surface area, which promotes more gas adsorption during thermal oxidation reactions. Nowadays, metallic iron nanoparticles can be synthesized via numerous methods, such as co-precipitation, sol-gel, microemulsion, or thermal decomposition. Although there are data on these synthetic methods in the literature, there is a lack of details related to nanoparticulate oxides and to their characterization techniques. In this context, this short review based on scientific papers, including data from the last two decades, presents methods for obtaining nanoparticulate iron oxides as well as the main aspects of the different characterization techniques and also about the decomposition aspects of these nanomaterials. Morphologies and structures of iron oxides can be characterized through transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy. As for textural properties, they are usually determined by physical adsorption techniques.
Accounts of Chemical Research, 1989
Gas-phase experiments with naked transition-metal ions offer a unique opportunity to probe, in ... more Gas-phase experiments with naked transition-metal ions offer a unique opportunity to probe, in the absence of any solvation, ion-pairing, and/or ligand effects, the intrinsic properties of reactive organometallic species and to evaluate the potential role these ...
Acta Crystallographica Section C Crystal Structure Communications, 2003
The structures of N-¯uoropyridinium tri¯uoromethanesulfonate, C 5 H 5 FN + ÁCF 3 O 3 S À , (I), a... more The structures of N-¯uoropyridinium tri¯uoromethanesulfonate, C 5 H 5 FN + ÁCF 3 O 3 S À , (I), and 1-¯uoro-2,4,6-trimethoxy-1,3,5-triazinium hexa¯uoroantimonate, (C 6 H 9 FN 3 O 3)[SbF 6 ], (II), are presented. The NÐF bond lengths in (I), a well known electrophilic¯uorinating agent, and its novel analogue, (II), are 1.357 (4) and 1.354 (4) A Ê , respectively.
Acta Crystallographica Section C Crystal Structure Communications, 1993
The N-F bond length of 1.407 (6) A in the title molecule is close to the value of 1.37 (2) ,& fou... more The N-F bond length of 1.407 (6) A in the title molecule is close to the value of 1.37 (2) ,& found in 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) [Banks, Sharif & Pritchard (1993).
Acta Crystallographica Section C Crystal Structure Communications, 2001
The title compound, N,N'-difluoro-N,N'-ethylenedi-p-toluenesulfonamide, C(16)H(18... more The title compound, N,N'-difluoro-N,N'-ethylenedi-p-toluenesulfonamide, C(16)H(18)F(2)N(2)O(4)S(2).CHCl(3), is a novel stable compound of the N-F class of reagents containing two R(2)N-F functionalities. The compound, as the chloroform solvate, is the first such bis(N-F) compound to be structurally characterized. It adopts a solid-state structure in which the two aromatic rings are antiperiplanar and a combination of weak C-H...F and C-H...O hydrogen bonds [distances and angles range from 3.265 (4) to 3.439 (4) A and 150 to 170 degrees, respectively] and pi-stacking between the rings of different molecules (separations of 3.717 and 3.926 A) results in a solid-state structure containing well defined channels in which CHCl(3) solvent molecules are located. The N-F distances are 1.428 (3) and 1.433 (3) A.
Journal of Fluorine Chemistry, 1995
Journal of Fluorine Chemistry, 1996
Journal of Fluorine Chemistry, 1996
Methods are described for the synthesis of 1-alkyl-4-aza-l-azoniabicyclo[2.
Journal of Fluorine Chemistry, 1997
Bis(4-fluoro-1,4-diazoniabicyclo[2.2.2]oct-1-yl)-ethane and -propane tetratriflates (4, 5), and 1... more Bis(4-fluoro-1,4-diazoniabicyclo[2.2.2]oct-1-yl)-ethane and -propane tetratriflates (4, 5), and 1,1′-difluoro-4,4′-bipyridinium ditriflate (6) were prepared by solution-phase direct fluorination of bis(4-aza-1-azoniabicyclo[2.2.2]oct-1-yl)-ethane or -propane ditriflate (10,11), and 4,4′-bipyridine respectively. The same technique was employed to convert the complex 4,4′-bipyridine · 2BF3 to the mono-NF derivative F3B·NC5H4-C5H4N+-F BF4− (7) and its monomethylated analogue (4-NC5H4)C5H4N+-CH4 TfO− to F- +NC5H4-C5H4N+-CH3 (TfO−)2 (8). The results of site-specific electrophilic fluorination of some model substrates (1-morpholinocyclohexene, phenol, 2-naphthol, anisole, di- and tri-methoxybenzene) with 5,7 and 8 are presented.
Journal of Fluorine Chemistry, 1996
Perfluoro-[N-fluoro-N-(4-pyridyl)acetamide] (2), prepared via direct fluorination of the sodium s... more Perfluoro-[N-fluoro-N-(4-pyridyl)acetamide] (2), prepared via direct fluorination of the sodium salt (4) of perfluoro-[N-(4-pyridyl)acetamide ], readily fluorinates diethyl sodio (phenyl) malonate [ ~ PhCF(CO2Et) 2 ], 1-morpholinocyclohexene (-, 2-fluorocyclohexanone), anisole (-, 2-and 4-FC~H4OMe), and phenol (-, 2-and 4-FC6H4OH) under mild conditions. The sodium salt precursor (4) of this sidechain N-F reagent (2) is easily made from pentafluoropyridine via the trifluoroacetylation of its 4-amino derivative or, more directly, by treating it with two equivalents of the monosodium salt of trifluoroacetamide.
Journal of Fluorine Chemistry, 2001
The¯uorine plus (F) detachment energy values (FPDE values) of the oxidative¯uorinators C 3 N 3 X ... more The¯uorine plus (F) detachment energy values (FPDE values) of the oxidative¯uorinators C 3 N 3 X 3 F (X H, F, Cl), which are structurally based on the 1,3,5-trihalogenotriazine moiety, and C 5 NX 5 F (X H, F, Cl), based on pyridine or pentahalogeno pyridine, have been computed quantum-chemically at the density functional B3LYP hybrid level of theory at a 6±31G(d,p) basis. The gas-phase¯uorine plus detachment energy values (FPDE) have been additively calibrated by an experimental value for KrF and have been determined to be:
Journal of Fluorine Chemistry, 2003
Chemical Communications, 1999
Unexpectedly, treatment of perfluoro(2,6-dimethyl-1-azacyclohexene) with 2 equiv. of PhLi in cycl... more Unexpectedly, treatment of perfluoro(2,6-dimethyl-1-azacyclohexene) with 2 equiv. of PhLi in cyclohexane-Et 2 O at 250 to 40 °C gives a good yield (72%) of (±)-3,3,4,4,5-pentafluoro-2,6-diphenyl-2,6-bis(trifluoromethyl)-1-azabicyclo-[3.1.0]hexane 1; the nitranion implicated in this novel conversion can be trapped with sulfuric acid, giving 2,2,4,4,5,5-hexafluoro-2(e),6(e)-diphenyl-2(a),6(a)-bis(trifluoromethyl)piperidine 5.
Journal of Fluorine Chemistry, 1997
During the past decade, N-fluoro-compounds prepared by direct fluorination techniques have featur... more During the past decade, N-fluoro-compounds prepared by direct fluorination techniques have featured prominently in the search for “ideal” (easily handled, safe-in-use, site-specific, enantioselective, transportable, relatively inexpensive) fluorinating agents capable of acting in a positive mode (POS-F Reagents). Reagents of the NF class developed recently in our laboratory, e.g. (1) – (4), will be discussed, and their fluorinating capabilities exemplified. Particular attention will be paid to power-adjustable reagents derived from TEDA, for which (4) is the prototype.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Journal of Fluorine Chemistry, Sep 1, 1991
Iron oxide is a mineral compound that shows different polymorphic forms, including hematite (α-Fe... more Iron oxide is a mineral compound that shows different polymorphic forms, including hematite (α-Fe 2 O 3), magnetite (Fe 3 O 4) and maghemite (γ-Fe 2 O 3). Solid propulsion technology nanoparticulate materials, such as hematite and maghemite, exhibit high performance on thermal decomposition of ammonium perchlorate. The enhanced catalytic effect of metallic iron oxide nanoparticles is attributed to their particle size, more active sites and high surface area, which promotes more gas adsorption during thermal oxidation reactions. Nowadays, metallic iron nanoparticles can be synthesized via numerous methods, such as co-precipitation, sol-gel, microemulsion, or thermal decomposition. Although there are data on these synthetic methods in the literature, there is a lack of details related to nanoparticulate oxides and to their characterization techniques. In this context, this short review based on scientific papers, including data from the last two decades, presents methods for obtaining nanoparticulate iron oxides as well as the main aspects of the different characterization techniques and also about the decomposition aspects of these nanomaterials. Morphologies and structures of iron oxides can be characterized through transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy. As for textural properties, they are usually determined by physical adsorption techniques.
Accounts of Chemical Research, 1989
Gas-phase experiments with naked transition-metal ions offer a unique opportunity to probe, in ... more Gas-phase experiments with naked transition-metal ions offer a unique opportunity to probe, in the absence of any solvation, ion-pairing, and/or ligand effects, the intrinsic properties of reactive organometallic species and to evaluate the potential role these ...
Acta Crystallographica Section C Crystal Structure Communications, 2003
The structures of N-¯uoropyridinium tri¯uoromethanesulfonate, C 5 H 5 FN + ÁCF 3 O 3 S À , (I), a... more The structures of N-¯uoropyridinium tri¯uoromethanesulfonate, C 5 H 5 FN + ÁCF 3 O 3 S À , (I), and 1-¯uoro-2,4,6-trimethoxy-1,3,5-triazinium hexa¯uoroantimonate, (C 6 H 9 FN 3 O 3)[SbF 6 ], (II), are presented. The NÐF bond lengths in (I), a well known electrophilic¯uorinating agent, and its novel analogue, (II), are 1.357 (4) and 1.354 (4) A Ê , respectively.
Acta Crystallographica Section C Crystal Structure Communications, 1993
The N-F bond length of 1.407 (6) A in the title molecule is close to the value of 1.37 (2) ,& fou... more The N-F bond length of 1.407 (6) A in the title molecule is close to the value of 1.37 (2) ,& found in 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) [Banks, Sharif & Pritchard (1993).
Acta Crystallographica Section C Crystal Structure Communications, 2001
The title compound, N,N'-difluoro-N,N'-ethylenedi-p-toluenesulfonamide, C(16)H(18... more The title compound, N,N'-difluoro-N,N'-ethylenedi-p-toluenesulfonamide, C(16)H(18)F(2)N(2)O(4)S(2).CHCl(3), is a novel stable compound of the N-F class of reagents containing two R(2)N-F functionalities. The compound, as the chloroform solvate, is the first such bis(N-F) compound to be structurally characterized. It adopts a solid-state structure in which the two aromatic rings are antiperiplanar and a combination of weak C-H...F and C-H...O hydrogen bonds [distances and angles range from 3.265 (4) to 3.439 (4) A and 150 to 170 degrees, respectively] and pi-stacking between the rings of different molecules (separations of 3.717 and 3.926 A) results in a solid-state structure containing well defined channels in which CHCl(3) solvent molecules are located. The N-F distances are 1.428 (3) and 1.433 (3) A.
Journal of Fluorine Chemistry, 1995
Journal of Fluorine Chemistry, 1996
Journal of Fluorine Chemistry, 1996
Methods are described for the synthesis of 1-alkyl-4-aza-l-azoniabicyclo[2.
Journal of Fluorine Chemistry, 1997
Bis(4-fluoro-1,4-diazoniabicyclo[2.2.2]oct-1-yl)-ethane and -propane tetratriflates (4, 5), and 1... more Bis(4-fluoro-1,4-diazoniabicyclo[2.2.2]oct-1-yl)-ethane and -propane tetratriflates (4, 5), and 1,1′-difluoro-4,4′-bipyridinium ditriflate (6) were prepared by solution-phase direct fluorination of bis(4-aza-1-azoniabicyclo[2.2.2]oct-1-yl)-ethane or -propane ditriflate (10,11), and 4,4′-bipyridine respectively. The same technique was employed to convert the complex 4,4′-bipyridine · 2BF3 to the mono-NF derivative F3B·NC5H4-C5H4N+-F BF4− (7) and its monomethylated analogue (4-NC5H4)C5H4N+-CH4 TfO− to F- +NC5H4-C5H4N+-CH3 (TfO−)2 (8). The results of site-specific electrophilic fluorination of some model substrates (1-morpholinocyclohexene, phenol, 2-naphthol, anisole, di- and tri-methoxybenzene) with 5,7 and 8 are presented.
Journal of Fluorine Chemistry, 1996
Perfluoro-[N-fluoro-N-(4-pyridyl)acetamide] (2), prepared via direct fluorination of the sodium s... more Perfluoro-[N-fluoro-N-(4-pyridyl)acetamide] (2), prepared via direct fluorination of the sodium salt (4) of perfluoro-[N-(4-pyridyl)acetamide ], readily fluorinates diethyl sodio (phenyl) malonate [ ~ PhCF(CO2Et) 2 ], 1-morpholinocyclohexene (-, 2-fluorocyclohexanone), anisole (-, 2-and 4-FC~H4OMe), and phenol (-, 2-and 4-FC6H4OH) under mild conditions. The sodium salt precursor (4) of this sidechain N-F reagent (2) is easily made from pentafluoropyridine via the trifluoroacetylation of its 4-amino derivative or, more directly, by treating it with two equivalents of the monosodium salt of trifluoroacetamide.
Journal of Fluorine Chemistry, 2001
The¯uorine plus (F) detachment energy values (FPDE values) of the oxidative¯uorinators C 3 N 3 X ... more The¯uorine plus (F) detachment energy values (FPDE values) of the oxidative¯uorinators C 3 N 3 X 3 F (X H, F, Cl), which are structurally based on the 1,3,5-trihalogenotriazine moiety, and C 5 NX 5 F (X H, F, Cl), based on pyridine or pentahalogeno pyridine, have been computed quantum-chemically at the density functional B3LYP hybrid level of theory at a 6±31G(d,p) basis. The gas-phase¯uorine plus detachment energy values (FPDE) have been additively calibrated by an experimental value for KrF and have been determined to be:
Journal of Fluorine Chemistry, 2003
Chemical Communications, 1999
Unexpectedly, treatment of perfluoro(2,6-dimethyl-1-azacyclohexene) with 2 equiv. of PhLi in cycl... more Unexpectedly, treatment of perfluoro(2,6-dimethyl-1-azacyclohexene) with 2 equiv. of PhLi in cyclohexane-Et 2 O at 250 to 40 °C gives a good yield (72%) of (±)-3,3,4,4,5-pentafluoro-2,6-diphenyl-2,6-bis(trifluoromethyl)-1-azabicyclo-[3.1.0]hexane 1; the nitranion implicated in this novel conversion can be trapped with sulfuric acid, giving 2,2,4,4,5,5-hexafluoro-2(e),6(e)-diphenyl-2(a),6(a)-bis(trifluoromethyl)piperidine 5.
Journal of Fluorine Chemistry, 1997
During the past decade, N-fluoro-compounds prepared by direct fluorination techniques have featur... more During the past decade, N-fluoro-compounds prepared by direct fluorination techniques have featured prominently in the search for “ideal” (easily handled, safe-in-use, site-specific, enantioselective, transportable, relatively inexpensive) fluorinating agents capable of acting in a positive mode (POS-F Reagents). Reagents of the NF class developed recently in our laboratory, e.g. (1) – (4), will be discussed, and their fluorinating capabilities exemplified. Particular attention will be paid to power-adjustable reagents derived from TEDA, for which (4) is the prototype.