CHM 2123 Study Guide - Midterm Guide: Nucleophilic Aromatic Substitution, Racemic Mixture, Leaving Group

• School: University of Ottawa
• Department: Chemistry
• Course: CHM 2123
• Professor: Katherine Mc Gilvray

Document Summary

Experiment 1: extraction and recrystallization of caffeine from black tea. To get rid: add nacl (brine )to ionically strengthens aqueous layer, forcing aqueous out of organic: na2so4 (drying agent) to the organic phase gets rid of trace amounts of aqueous. Sublimation: change of state from solid to gas, can use cold finger. If put too far from the bottom of flask, there is a lower vapor pressure higher up, so they will get lower yield. Use if you only have a small amount of product that you want to purify: allows for recrystallization and purification (because it occurs at a temperature specific to the caffeine) Tlc: monitor progression of reaction, three lanes: starting materials, co-spot and reference, more polar substances don"t climb as far up on the tlc plate because they interact with the polar silica gel. Polar: often dependent on capacity for hydrogen bonding (with strongly en atom: always write solvent, rf calculation: distance solute travelled/distance solvent travelled.