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1. syhtesis-of-phynetoin-students.pdf
The document summarizes the synthesis of the anti-epileptic drug phenytoin. It involves a two-step process: (1) benzoin condensation to form benzil from benzaldehyde, followed by oxidation; (2) reaction of benzil with urea in ethanol and sodium hydroxide to form an intermediate that undergoes rearrangement in acid to yield phenytoin. The required chemicals, equipment, procedure, calculations for theoretical and percent yield are provided. Phenytoin works by binding to voltage-gated sodium channels in neurons to reduce repetitive firing and prevent seizure discharge.
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1. syhtesis-of-phynetoin-students.pdf
- 1. Synthesis of Phenytoin Dr.Pawan Kumar Gupta Associate Professor SVKM's Institute of Pharmacy, Dhule, Maharashtra https://sites.google.com/view/pawanpharma79/about-me?authuser=1
- 2. Introduction • Phynetoin isanti- epileptic drug • Hydantoin derivative Phynetoin (5,5-diphenylimidazolidine-2,4-dione)
- 3. Mechanism of Action •Phenytoin bind voltage dependant Sodium ion channel • It prolong the inactive stage of sodium ion channel • It reduces the entry of sodium ion inside the neuronal membrane • Inhibition of repetitive generation of action potential • Prevention of discharge of seizure • phenytoin
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- 6. Principle • 1. Formationof the benzil form benzaldehyde: • Benzoin condensation: In presence of the NaCN, two molecules of the benzaldehyde are reacted and formed the benzoin (2-hydroxy-1,2-diphenylethan- 1-one). In the presence of the FeCl3 and acid, 2-hydroxyl group is get oxidized into carbonyl group and formed benzil (diphenylethane-1,2-dione) • 2. Formation of phenytoin from benzil: • It is base catalysed reaction followed by pinacol-pinacolone rearrangement. • In presence of the NaOH/EtOH and HCl (10%), reaction between benzil and urea are undergone intramolecular cyclization and formed pinacol intermediate (4,5- dihydroxy-4,5-diphenylimidazolidin-2-one). This intermediate is containing two hydroxyl groups in adjacent carbon (vicinal diol). In the acidic medium, this intermediate is undergone for pinacol-pinacolone rearrangement (diphenyl shift) and eventually get converted into the phenytoin.
- 7. • REQUIREMENTS • Roundbottom flask • Measuring cylinder • Beaker • Pipette • Funnel • Reflux condensor • Glass rod • Filter paper • Dropper
- 8. Chemicals required: •Benzil •Urea •EtOH •NaOH (30%w/v solution) •HCl
- 9. Procedure • 1. Take2 gm of the benzil and transfer it into RBF (Round bottle flask). • 2. Take 1.2 gm urea and add into RBF • 3. Add 10 ml of ethanol into the RBF • 4. Mix well and 10ml of 30 % NaOH solution into RBF • 5. Attach the RBF to the reflux condenser and boil the content on water bath for 2 hrs. • 6. Transfer the reaction mixture into the beaker. • 7. Keep the beaker on the ice-bath and add 10ml of the cold water into the reaction mixture. Allow the mixtures to keep it for sometime. • 8. In the reaction mixture, formation of the by-product is appeared. • 9. To remove the by product, filter the content with the help of funnel and filter paper. • 10. After the filtration, acidify the filtrate with 20% HCl drop-by-drop into the beaker (in order to get around pH2). Precipitation of the is appeared in the beaker. • 11. Filter out the precipitate content with the help of the funnel and filter paper. • 12. This precipitated content are stick on the filter paper and it is crude phenytoin which can be again recrystalized by using EtOH. • 13. Prepare TLC with Starting chemical (Benzil), final crude phenytoin and standard phenytoin. And calculate Rf value of them.
- 10. Calculations • Molecular weightthe Benzil: 210.2 • Molecular formula of Benzil: C14H10O2 • Molecular formula: C15H12N2O2 • Molecular weight the phytenoin: 252.26 • 1 mol of the benzil is equivalent to 1 mol of the phenytoin
- 11. • Theoretical yield: •210.23 gm benzil forms 252.26 gm phenytoin • 1 gm-------------------------------= 252.26/210.23 • X gm------------------------------= (252.26/210.2)*x • Therefore, ___2 gm benzil will form …….? (X) g phenytoin • X =(252.26 × __2__)/210.23 = 2.399 gm • Theoretical yield = 2.399 gm • Practical yield = 2.16 gm
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- 13. • Use ofPhenytoin: • Anticonvulsants/antiepiletic drug: to control certain type of seizures, and to treat and prevent seizures that may begin during or after surgery to the brain or nervous system
- 14. Video links • https://www.youtube.com/watch?v=bss7gmuWJRk •https://www.youtube.com/watch?v=59jG3I7wRpQ • https://www.youtube.com/watch?v=p5rXWRobVRg • https://www.youtube.com/watch?v=sKs-sE28x14 • Synthesis of Benzil • https://www.youtube.com/watch?v=upcNzdd5M7s