Experiment 2 Preparation of N-Butyl Bromide (1 ... - PCC

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$Melting Point, Boiling Point, and Index of Refraction - PCC$

Exp. 2 butyl bromide 2 Boil the mixture well by heating the flask with a Bunsen flame for 30 minutes. (The reaction mixture will turn yellowish, brownish or black!). Allow the reaction mixture to cool down for about 3 minutes. Remove the condenser and arrange the flask for distillation. To the end of the condenser is attached a receiver adapter which leads into a 50 ml Erlenmeyer flask containing 10 ml of water. The receiving flask itself is cooled with a bath of ice and water. Screw cap Water Out Water In to sink Connect to tap carefully and adjust flow to give a gentle flow. Boiling chips Thermometer (note position of the bulb) Screw cap with teflon ring washer Clamp Distillation Assembly Reflux Condenser Ice water mixture to reduce evaporation of the distillate Heat the flask strongly so that liquid distils steadily. Oily drops should appear in the bottom of the receiver. Continue the distillation until no more oil drops distil into the water. In order to determine when to stop, make the following test. Remove the Erlenmeyer and place a test tube containing 2-3 mL of water over the end of the adapter. If no oily drops collect at the bottom of the test tube within a few minutes, the distillation is complete. Also, foaming of the liquid in the distillation flask is a sign that only water is distilling now and your product is already distilled over. Chem 266L Steven Forsey Discard the residue from distillation flask into the waste container at the front sink. Do not
throw the aqueous waste into the organic acetone waste containers!!!!!!!!!!!!!! Exp. 2 butyl bromide 3 Pour the distillation from the Erlenmeyer flask into a separatory funnel and draw off the lower nbutyl bromide layer into a clean flask. Keep the aqueous (upper) layer aside and at the end of the experiment through the waste into the aqueous waste container in the front sink). Return the n-butyl bromide layer into the separatory funnel and shake well with a roughly equal volume of 10% aqueous solution of sodium carbonate. (Why do you do this?) Carefully withdraw the n-butyl bromide into a clean dry, 50 ml size Erlenmeyer anhydrous flask. Add pellets of CaCl2 until the liquid is clear and CaCl2 no longer clumps together. (Usually, about half a teaspoon of CaCl2 is sufficient). Allow to stand for 5 minutes with occasional swirling to help absorption of any residual H2O by CaCl2. Clean and dry (using a heat gun) the Claisen head, condenser, receiver adapter, 50 ml size roundbottom flask and a 50 ml size Erlenmeyer flask. Wipe the thermometer dry with a paper towel. Decant the n-butyl bromide into the clean dry 50 ml round-bottomed flask; clamp the flask onto a rod-stand in the fume hood. Set up a distillation assembly using all the dried equipment and use the dry 50 ml Erlenmeyer flask as the receiver. Distil the n-butyl bromide using a Bunsen burner and record the temperature of the thermometer when its reading has stabilized (usually halfway through the distillation). This temperature is the boiling point of the n-butyl bromide and it must be reported in your lab write-up. When the distillation is complete, transfer the product, using a Pasteur pipette, into a pre-weighed vial and weigh it again. Report the mass of your product and the percentage yield. Keep the product vial tightly capped and labelled with both partner’s names. (Do not move it out of the laboratory). Submit the whole product vial with your report. Questions: 1. In the following reactions indicate which compounds are Lewis acids and bases on both sides of the arrows. Also state which way the equilibrium will be shifted i.e. to the right or left. Chem 266L Steven Forsey CH3CH2ONa + CH3CH2CH2I » CH3CH2CH2OCH2CH3 + NaI CH3CH2NH3 + + I - » NH3 + CH3CH2-I NaCN + CH3Br » CH3CN + NaBr CH3CO2CH3 + NaBr » CH3CO2Na + CH3Br CH3CH2OH + NaBr » CH3CH2Br + NaOH
Page 1: Introduction: Experiment 2 Preparat
Page 5 and 6: Chem 266L Steven Forsey Prelab Exp.

Experiment 2 Preparation of N-Butyl Bromide (1 ... - PCC

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