Single-Pot Processing
Dilip M. Parikh in Handbook of Pharmaceutical Granulation Technology, 2021
When producing expensive pharmaceutical products, the yield is one of the most important criteria to consider. Compared with the combination of a high-shear granulator and a fluid-bed dryer or even a fluid-bed spray granulator, a single pot has a much smaller surface area in contact with the product. Also, no fluidization with the associated risk of material sticking to the process filters happens. Should a processor equipped with microwaves be used, the microwave energy can be used to evaporate the granulation liquid while, at the same time, the wall temperature of the processor is kept close to that of the product, minimizing the amount of material that sticks to the processor wall. As a result, yields in excess of 99% can be realized.
Techniques for Performing Stoichiometric Calculations
Patrick E. McMahon, Rosemary F. McMahon, Bohdan B. Khomtchouk in Survival Guide to General Chemistry, 2019
Stoichiometric calculations provide a method for comparing any given amount of reactant or product to the specific amount of another reactant required in the process or the specific amount of a product that can be formed by the process. The calculation can determine the maximum specific amount of a selected product that can be formed from a specific given amount of reactant. This value is called the theoretical yield (T.Y.) of that product, expressed in moles, grams, or other units.The calculation can determine the specific amount of a selected reactant that is required to form a specific given amount of product based on theoretical yield.The calculation can determine the specific amount of a one selected reactant that must be reacted in the proper ratio with another given amount of reactant, assuming no reactant is in excess and the theoretical yield applies.The actual (experimental) yield of a specific product in a reaction can be compared to the maximum possible yield (theoretical yield) through a determination of percent yield.Under conditions where one reactant is present in a limited amount (limiting reagent), compared to other reactants that are in excess, a complete calculation can be performed to determine the amount of all reactants and products present after completion of a reaction based on theoretical yield.
Biodiesel Production from Microalgal Biomass
Gokare A. Ravishankar, Ranga Rao Ambati in Handbook of Algal Technologies and Phytochemicals, 2019
The process of transesterification is affected by various factors like the molar ratio of alcohol to oil, type and the amount of catalyst, reaction time and temperature and purity of reactants. However, transesterification is an equilibrium reaction in which an excess of alcohol is required to drive the transesterification reaction for completion. The presence of a sufficient amount of methanol during the transesterification reaction is essential to break the glycerine–fatty acid linkages (Al-Widyan and Al-Shyoukh 2002). Being polar and shortest chain alcohol, methanol can quickly react with triglycerides. The catalyst is usually used to improve the reaction rate and yield. The transesterification reaction can be catalyzed by alkalis, acids, enzymes and nanoparticles. The KOH and NaOH are commonly used as nbase catalyst for biodiesel preparation. However, during the separation of the final products from glycerol, KOH has been found to be more convenient (Guan et al. 2009). However, one limitation to the alkali-catalyzed process is its sensitivity to the purity of reactants. The alkali-catalyzed system is very sensitive to both water and FFA. The presence of water may cause saponification under alkaline condition. Acids used for transesterification include sulfuric, phosphoric, hydrochloric and organic sulfonic acids. It was rep orted that ester conversion reached 98% at a molar ratio of 30:1 (methanol:oil) with 3% sulfuric acid as a catalyst at 60°C. As acid-catalyzed transesterification is a relatively slow process, many researchers have combined both acidic and alkaline catalysts in a two-step reaction in which the acid treatment converts the FFA into esters while the alkaline catalyst is performing the transesterification. This process has been developed by Canacki and Garpen (2001) using yellow and brown grease having FFA content of more than 10%.
Eudragit S100 coated microsponges for Colon targeting of prednisolone
Published in Drug Development and Industrial Pharmacy, 2018
Amrita Kumari, Ankit Jain, Pooja Hurkat, Ankita Tiwari, Sanjay K. Jain
PLMs were prepared by quasi-emulsion solvent diffusion method using different drug amount [17,–19]. The internal phase consisted of EC (50 mg) and TEC (1% v/v) which were dissolved in 5 ml ethanol (95%). The PRD was added to this internal phase with constant stirring (500 rpm) using mechanical stirrer (REMI RQ1217-D, India). The internal phase was then poured into 0.5% w/v PVA in water. After stirring of 6 h, the PLMs were formed upon removal of ethanol from the system. They were filtered and dried (Yorco Hot Air Sterilization Oven, India) at 40 °C for 12 h and weighed to determine the product yield [20]. The different formulation of PLMs named PLM1, PLM2, PLM3, and PLM4 were prepared using drug:polymer ratio of 3:1, 6:1, 9:1, and 12:1, respectively. EC, TEC, and ethanol amount were kept constant, i.e. 50 mg, 1% v/v, and 5 ml, respectively. Each formulation was carried in triplicate. The product yield of PLMs was determined by calculating the initial weight of the raw materials and the final weight of the PLMs obtained [21]. The following formula was used to calculate product yield.
Synthesis and biological evaluation of 3-arylbenzofuranone derivatives as potential anti-Alzheimer’s disease agents
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Jie Yang, Yinling Yun, Yuhang Miao, Jie Sun, Xiaojing Wang
Compared with the original method, the ratio of mandelic acid compounds to phenolic compounds was adjusted from 1:1 to 1:1.2 to ensure that the mandelic acid compounds fully reacted. The completion of the reaction is monitored by thin layer chromatography (TLC), not just the reaction time. Compounds with different substituents differ greatly in reaction time. Excessive reactions can affect compound yield and purity. Several polyhydroxy compounds were synthesised by microwave reactions. The previous reaction by heating in an oil bath required a reaction for 8 h, and now the reaction time is shortened to 15 min by 200 W microwave heating. The yield of the compound obtained by microwave heating is also slightly improved. Most 3-arylbenzofuranone compounds can be purified by methanol recrystallisation, which is efficient and fast.
Evaluation of the environmental impact of magnetic nanostructured materials at different trophic levels
Published in Nanotoxicology, 2021
Roberto Carlos Valerio-García, Iliana E. Medina-Ramírez, Mario A. Arzate-Cardenas, Ana Laura Carbajal-Hernández
The synthesis consisted of the addition of 165 mg of FeCl3 and 250 mg of FeCl2 • 4H2O to 150 ml of the organic coating solution: sodium citrate (0.1 M), PVP (0.1 M), glycine (0.1 M) and Arabic gum (2.5%) respectively. The mixtures were stirred for 15 minutes. Then, 20 mL NH4OH (28%, v/v) was dropwise added, and the resulting solutions were kept at 70° C under continuous stirring for 2 h. Magnetic particles were separated with the aid of a magnet and washed three times with ethyl ether (10 mL) and absolute ethanol (10 mL). Once the powder was dried after ether evaporation, it was then homogenized in the mortar and sonicated for 5 min. The reaction yield was about 90%. Finally, each material was analyzed based on its colloidal stability.
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