Body

245 * Lab #8

Dehydration of t-Amyl Alcohol ( 2-methyl-2-butanol)

Procedure:

Set up a fractional distillation with a wrapped Vigreux (or unpacked Hemple) column. (See page 12 although you will now use a Flask as the receiver) Use a 25 mL still pot and a 50 mL receiver. Unclip or unclamp the pot and add about 15 mL (measured precisely) of t-amyl alcohol. Cool the pot on ice and slowly add, with swirling, ~ 5 mL of 9 M Sulfuric acid (H₂SO₄). Add a couple of boiling chips, reattach the still pot, and heat with a heating mantle (~50% power). When the pot begins to boil, start checking the head temperature.

Put an ice bath under the receiver before the product starts to distill. (What will be the approximate temperature?) Stop distilling when 1/2 to 2/3 of the pot contents are gone, OR, when the head temperature abruptly begins to increase.

Detach the receiver and add ~ 1 gram anhydrous Na₂SO₄ and two pellets (0.2 g) sodium hydroxide (NaOH) to the receiver. Use the 25 mL flask as your receiver, and attach a drying tube to the vacuum adapter (See chapter 2). Pre weigh the 25 mL flask on a cork ring. Be sure the distillation apparatus is clean and dry.

Distill your alkene (s) until the pot is almost dry, into an ice-chilled receiving flask. Record the B.P. range of your alkene (s) and the weight. These alkenes are saved to be used as the reactant for the lab "Addition Reaction of HBr to an Alkene Mixture". Store them tightly sealed in the refrigerator until next week.

Pre lab questions to consider before lab:

1.) 60 gms of 2- propanol undergo elimination to form propene. How many grams of propene are made? (Assume 100% yield)

2.) What is the structure of t-amyl alcohol? It's M.W.? It's B.P.?

3.) What product (s) are formed? Their structures? M.W.'s ? B.P.'s ?

4.) Why the emphasis on dryness during the simple distillation?

WASTE Spill & Disposal D: T-amyl alcohol (non-listed), Butene products are collected and kept by instructor.

WASTE Spill & Disposal A: Sulfuric Acid, Sodium Hydroxide, Sodium Sulfate, & * the still pot residue may go into the sink followed by water. *

WASTE Spill and Disposal - E: Any acetone used to clean glassware. *THERE IS AN ACETONE WASTE JUG IN THE HOOD *
DO NOT PUT USED WEIGH BOATS IN THE HW CHEMICAL CONTAINER. CONTAMINATED PAPER TOWELS AND WEIGH BOATS ARE PUT INTO THE CLEAR PLASTIC HW BOX IN THE HOOD. PAPER ENVELOPES W/CHEMICALS SHOULD BE FOLDED MULTIPLE TIMES AND SEALED BEFORE BEING PUT INTO THE SPECIFIED HW CONTAINER.

CHEMICALS:	LOCATION
t-amyl alcohol (10 mL)	Hood #5
* 9 M Sulfuric Acid (Corrosive) (5 mL)	Hood #5
* Sodium Hydroxide (Corrosive)	Hood #5
Sodium Sulfate, anhyd.	Hood #5

SUPPLIES:
Drying tubes/ CaCl₂	White Supply Cabinet
boiling chips	Org_prep
Vigreux column	White Supply Cabinet
aluminum foil	Org_prep
Cork rings	Org_prep