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61.
Desai S. R. Shaikh M. M. Dharwadkar S. R. 《Journal of Thermal Analysis and Calorimetry》2003,71(2):651-658
Chemical compatibility of two drugs, namely, etamsylate and fluconazole was studied with lactose as excipient, employing differential
scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. The DSC patterns recorded for the mixtures of both the
drugs with the common excipient (lactose) indicated that fluconazole as well as etamsylate were incompatible with lactose
at high temperatures. X-ray diffraction patterns recorded for pure drugs and lactose and the mixtures of individual drugs
with lactose prepared at room temperature by intimate grinding of the components revealed incompatibility of both the drugs
with lactose also at room temperature.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
62.
Mohamed Rifaat Hamza Elmoghayar Mohamed Hilmy Elnagdi Mohamed Kamal Ahmed Ibrahim Mohamed Mohamed Mohamed Sallam 《Helvetica chimica acta》1977,60(7):2171-2176
The Carbo(3-phenylpyrazol-5-yl-hydrazonoyl) halides 1a , b react with active methylene compounds to yield the 1-(3-phenylpyrazol-5-yl)-pyrazole derivatives 2a – k (Scheme 1). The acyclic intermediates 3a , b could be isolated from reaction of 1a , b with acetylacetone, thus establishing the substitution mechanism for these reactions. Compounds 1a , b reacted with carbon disulfide, phenyl isothiocyanate, methyl cyanide, and with p-chlorobenzaldehyde to yield the corresponding heterocyclic derivatives 5 – 8 , respectively (Scheme 2). The behaviour of compounds 2 with hydrazine hydrate is reported. 相似文献
63.
Ahmed Kamal K. Laxma Reddy V. Devaiah N. Shankaraiah Y. Narasimha Reddy 《Tetrahedron letters》2004,45(41):7667-7669
A methodology based on reductive cleavage followed by cyclization, for the solid-phase synthesis of pyrrolo[2,1-c][1,4]benzodiazepines employing DIBAL-H, is described. 相似文献
64.
Ahmed Abd El-Fattah Mohamad Nageeb Hassan Ahmad Rashad Mona Marei Sherif Kandil 《International Journal of Polymer Analysis and Characterization》2020,25(5):362-373
Abstract An injectable composite hydrogel composed of polyvinyl alcohol (PVA) and bioactive glass (BG) particles were synthesized by a physical crosslinking approach. The morphology, mechanical properties, and viscoelasticity of the PVA/BG composite hydrogel were characterized. Scanning electronic microscopy (SEM) showed uniform and homogeneous distribution of BG particles throughout the composite hydrogel. The incorporation of 2.5?wt% of BG particles in the composite hydrogel formulations, enhanced the static compressive strength and static elastic modulus by 325% and 150%, respectively. The storage molds (G′) was greater than the loss modules (G′′) at all the frequency range studied, which revealed a self-standing elastic composite hydrogel with a smooth injectability. The PVA/BG composite hydrogel was also implanted subcutaneously in the dorsal region of adult male rats. After 4?weeks of implantation, no inflammatory cells were seen within and around the implant, which indicated that the composite hydrogel was biocompatible. The properties of the synthesized injectable PVA/BG composite hydrogel demonstrate its capability toward bone regeneration. 相似文献
65.
A.A. Ahmed I.M. Youssof A.F. Abbas O. Abou Eleinen 《Journal of Sol-Gel Science and Technology》1998,13(1-3):753-756
The chemical durability of lead glass tumblers (24% PbO) in a 4% (v/v) acetic acid solution before and after coating with sol-gel derived SiO2 films was assessed to determine the extent of reduction in Pb-leaching that can be achieved. It was found that by coating the internal surface of the glass tumblers with 1 ml of 10% TEOS solutions at 100°C and densifying the coating formed at 500°C for 1 h, it was possible to reduce Pb-leaching to about one quarter of that of the uncoated glass. 相似文献
66.
The solvation parameter model is used to elucidate the retention mechanism on a perfluorohexylpropylsiloxane-bonded (Fluophase
RP) and octadecylsiloxane-bonded (Betasil C18) stationary phases based on the same silica substrate with acetonitrile–water
and methanol–water mobile phase compositions. Dewetting affects the retention properties of Fluophase RP at mobile phase compositions
containing less than 20% (v/v) acetonitrile or 40% (v/v) methanol. It results in a loss of retention due to an unfavorable change in the phase ratio as well as changes in specific
intermolecular interactions. Steric repulsion reduces retention of bulky solutes on fully solvated Betasil C18 with methanol–water
(but not acetonitrile–water) mobile phase compositions but is not important for Fluophase RP. The retention of weak bases
is affected by ion-exchange interactions on Fluophase RP with acetonitrile–water, and to a lesser extent, methanol-water mobile
phases but these are weak at best for Betasil C18. The system constants of the solvation parameter model and retention factor
scatter plots are used to compare selectivity differences for Fluophase RP, Betasil C18 and a perfluorophenylpropylsiloxane-bonded
silica stationary phase Discovery HS F5 for conditions where incomplete solvation, steric repulsion and ion-exchange do not
significantly contribute to the retention mechanism. Lower retention on Fluophase RP results from weaker dispersion and/or
higher cohesion moderated to different extents by polar interactions since solvated Fluophase RP is a stronger hydrogen-bond
acid and more dipolar/polarizable than Betasil C18. Retention factors for acetonitrile–water mobile phases are highly correlated
for Fluophase RP and Betasil C18 except for compounds with a large excess molar refraction and weak hydrogen-bonding capability.
Selectivity differences are more significant for methanol–water mobile phases. Retention factors on Fluophase RP are strongly
correlated with those on Discovery HSF5 for acetonitrile–water mobile phases while methanol–water mobile phases retention
on Fluophase RP is a poor predictor of the retention order on Discovery HS F5. 相似文献
67.
Mohamed S. A. El‐Gaby Ahmed M. Sh El‐Sharief Ahmed A. Atalla Abu‐Bakr A. A. M. El‐Adasy 《中国化学会会志》2004,51(2):327-333
The novel cyanothioformamides 2a‐d were prepared by treatment of isothiocyanatosulfonamides 1a‐d with potassium cyanide at room temperature. Cyclocondensation of compounds 2b,c with phenyl isocyanate as electrophile furnished the corresponding imidazolidines 3a,b . The reactivity of compound 3a towards some nitrogen nucleophiles was investigated. Thus, the thiosemicarbazone 4 and imidazo[4,5‐b]quinoxaline 6 were synthesized by condensation of compound 3a with thiosemicarbazide and o‐phenylenediamine, respectively. Treatment of 3a with hydrochloric acid afforded compound 7 . Our investigation was extended to include the reactivity of cyanothioformamide 2 towards o‐aminophenol, anthranilic acid, and o‐phenylenediamine and yielded the corresponding heterocycles 9 , 11 and 13 derivatives, respectively. Structures of the synthesized compounds were established by their elemental analysis and spectral data. 相似文献
68.
Diethazine hydrochloride, butaperazine dimaleate, trifluoperazine hydrochloride, promethazine hydrochloride, prochlorperazine maleate and chlorpromazine hydrochloride have been studied as indicators in bromate titration of quinol, metol and ascorbic acid. They give a very sharp reversible colour change at the equivalence point. Their formal potentials have been determined. A simple but accurate method for the estimation of quinol and metol is reported. 相似文献
69.
Borrowing hydrogen from alcohols, storing it on a catalyst and subsequent transfer of the hydrogen from the catalyst to an in situ generated imine is the hallmark of a transition metal mediated catalytic N-alkylation of amines. However, such a borrowing hydrogen mechanism with a transition metal free catalytic system which stores hydrogen molecules in the catalyst backbone is yet to be established. Herein, we demonstrate that a phenalenyl ligand can imitate the role of transition metals in storing and transferring hydrogen molecules leading to borrowing hydrogen mediated alkylation of anilines by alcohols including a wide range of substrate scope. A close inspection of the mechanistic pathway by characterizing several intermediates through various spectroscopic techniques, deuterium labelling experiments, and DFT study concluded that the phenalenyl radical based backbone sequentially adds H+, H˙ and an electron through a dearomatization process which are subsequently used as reducing equivalents to the C–N double bond in a catalytic fashion.An efficient method is developed for harvesting hydrogen, its storage and catalytic transfer by an odd alternant hydrocarbon. The strategy is reminiscent of transition metals in borrowing hydrogen mediated processes. 相似文献
70.
Namita Singh Sana Ahmed Aliyah Fakim Somayah Qutub Othman Alahmed Omar El Tall Osama Shekhah Mohamed Eddaoudi Niveen M. Khashab 《Chemical science》2020,11(41):11280
Assembling well-defined MOF superstructures remains challenging as it requires easily removable hard templates or readily available immiscible solutions for an emulsion-based soft-template approach. In this work, a single-step emulsion-free soft templating approach is reported to spontaneously prepare hollow ZIF-8 and ZIF-67 colloidosomes with no further purification. These superstructures can load different enzymes regardless of the size and charge with a high encapsulation efficiency of 99%. We envisage that this work will expand the repertoires of MOF superstructures by the judicious selection of precursors and the reaction medium.An emulsion-free approach for the preparation of hollow ZIF-8 superstructures in a single step is established based on metal sulfate hydrates in methanol. 相似文献