نتایج جستجو برای: heterogenous solid acid
تعداد نتایج: 926676 فیلتر نتایج به سال:
The solid–solid reactions of electron-donor compounds, such as: barbituric acid (1a), thiobarbituric acid (1b), 1,3-dimethyl barbituric acid (1c), phenol (1d) and resorcinol (1e) with diazotized o-nitroaniline (3), m-nitroaniline (4) and p-nitroaniline (5) catalyzed by p-toluenesulfonic acid (2) afford azo dyes by grinding in good yields. This new method totally avoids the use of inorganic acid...
a simple, efficient and clean procedure has been developed for the cleavage of imines c=n bond. deprotection of imines to their parent carbonyl and amine compounds was achieved using p-toluenesulfonic acid in the solid state condition at 25-45 ˚c. the salient features of this methodology are shorter reaction times, cheap processing, high yields of product and easy availability of the catalyst. ...
Solid-pseudopapillary tumour of the pancreas is a rare benign or low-grade malignant epithelial tumour that occurs mainly in young females. Pathologic and imaging findings include a well-defined, encapsulated pancreatic mass with cystic and solid components with hemorrhage. We report a 23-year-old woman that presented with epigastric pain of long duration and epigastric mass on palpation. MDCT ...
the esterification of free fatty acids (ffa) with methanol is studied using sulfonated porous carbon (spc) as catalyst. in compare to the amorphous sugar catalyst and protonated nafion, the proposed catalyst shows stability and high efficient performance in biodiesel production. the highest initial rate of oleic acid conversion is obtained at catalyst loading of 1 mmol h+ and mole ratio of meoh...
A 65 year old postmenopausal female presented with left sided abdominal pain. Sonogram revealed an intra-abdominal 7.4 x 5.7 cm heterogenous mass. On laparotomy, approximately 10 X 10 cm mesenteric mass was seen adherent to the descending colon. Multiple omental tumor deposits were also noted. Gross examination showed solid and cystic tumor with sebaceous material admixed with hair. Histopathol...
Third ventricular cavernous angiomas are rare vascular malformations of the brain. We report an eight-year old boy with a rare third ventricular cavernous angioma that hemorrhaged presenting with symptoms of acute hydrocephalus. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) showed a heterogenous ill-defined, solid and cystic intraventricular mass in the third ventricle which was...
Post-transplant lymphoproliferative disease (PTLD) describes a heterogenous group of lymphoproliferative diseases, occurring as a result of uncontrolled B cell proliferation in the context of post-transplant immunosuppression. The incidence depends on the type of transplant and immunosuppression used; the median time to onset is shorter for recipients of stem cell transplants (2 months) than th...
This study reports the application of metallo-stannosilicates as potential inorganic solid matrixes for enzymes immobilization and their use a heterogenous catalysts in enzymatic transesterification reactions conversion triacylglycerides into fatty acid ethyl esters (FAEEs). Several stannosilicates were synthesized physicochemical characterized by X-ray powder diffraction (XRD), scanning electr...
Silica-bonded n-propyldiethylenetriamine sulfamic acid (SBPDSA) was found as an efficient solid acid for the synthesis of coumarins. Coumarin derivatives were obtained via the Pechmann condensation reaction of phenols and β-keto-esters at 80 oC under solvent-free conditions. Also, biscoumarins were obtained via the condensation of aldehydes and 4-hydroxycoumarin in water at reflux conditions. T...
abstract effect of different concentrations of salicylic acid on postharvest life of kiwifruit (actinidia deliciosa) cultivar hayward at 0 ±.5 °c and 90-95% rh was studied. fruits were treated with salicylic acid (0, 1 and 2 mmol/l-1) and stored at 0±.5°c for 16 weeks. fruit quality attributes assessment including firmness, total acidity, soluble solid content, ascorbic acid, antioxidant activi...
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