Pre Lab 1 - pre lab PDF

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pre lab...

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Jessie Hays 1/31/19 Thursday 12:30-3:15 TA: Kun Wang

Title: Discovering the Unknown Treasures of Alcohols Introduction: In this lab, students will be extracting an unknown alcohol from solution. Through a series of tests, students will be able to isolate the alcohol for spectroscopy. The goal of the spectroscopy is to identify key groups of the alcohol in order for identification. The spectroscopy used today by the students will be FTIR and HNMR Potential identities include 2-pentanol, 3pentanol, and 3-methylbutan-2-ol. Techniques used by the students include quenching, liquid/liquid extraction, gravity filtration, FTIR spec, and HNMR spec. These techniques have been used in the first semester organic chemistry and should not be a problem for the students to use in this lab. Reagents Reagent

MW g/mol

MP °C

BP °C

Density g/cm^3

2-pentanol

88.15

-73

119

n/a

Solubility in water g/L @ 25°C n/a

Safety

3-pentanol

88.15

-8

116

n/a

n/a

3methylbutan2-ol

88.15

-147

130

n/a

n/a

Glacial acetic acid

60.05

16.6

118.1

n/a

n/a

Flammable as liquid and vapor. Causes skin burns, eye damage.

Sodium hypochlorite

74.439

n/a

n/a

n/a

n/a

Sodium bisulfite

104.06

n/a

n/a

n/a

n/a

Corrosive to metals. Causes severe burns and damage to eyes, skin, respiratory, and clothing. Very toxic to aquatic life. Do not get on skin, harmful if absorbed. Do not swallow.

Flammable as liquid and vapor. Causes skin irritation, eye irritation, may cause respiratory irritation Flammable as liquid and vapor. Causes skin irritation, eye irritation, may cause respiratory irritation Flammable as liquid and vapor. May cause respiratory irritation

Jessie Hays 1/31/19 Thursday 12:30-3:15 TA: Kun Wang

Sodium hydroxide

40.0

n/a

n/a

n/a

n/a

Severe skin burns and eye damage

Magnesium sulfate anhydrous

120.361 n/a

n/a

n/a

n/a

Do not swallow, touch, or breathe in.

Methylene chloride

84.927

n/a

n/a

n/a

n/a

Water

18

n/a

100

1

n/a

If inhaled, may cause drowsiness. Serious eye irritation. Cancer causing agent. Repeated exposure causes organ damage. n/a

Brine

58.44

n/a

108

1.2

n/a

Strcutures 2-pentanol

3-pentanol

3-methylbutan-2-ol

Glacial acetic acid

Sodium hypochlorite

Sodium bisulfite

Mild respiratory irritation, may cause dry skin if exposed.

Jessie Hays 1/31/19 Thursday 12:30-3:15 TA: Kun Wang

Sodium hydroxide

Magnesium sulfate anhydrous

Methylene chloride

Water

Brine

Procedural Safety Lab coats, goggles, and gloves need to be worn at all times. Many reagents are very harmful to the skin and eyes. The fume hood needs to be used to store the liquid reagents when not in use. Snorkels need to be turned on and in use over the reagents when being used. Reagents need to be disposed of in marked containers and not dumped down the drain or regular trash. Many of the reagents are harmful to aquatic life. Reagents need to be kept away from flames or heating sources.

Jessie Hays 1/31/19 Thursday 12:30-3:15 TA: Kun Wang

Equation and Mechanism

Procedure 1. 2. 3. 4. 5. 6. 7.

8.

9.

Get 2.1 g of unknown alcohol from TA. Record unknown code (this is the only way you will know which alcohol you have) Prepare an ice bath for 100 mL round bottom flask Add stir bar and 1.75 mL of glacial acetic acid (to flask) As flask is cooling in ice bath add 36 mL of sodium hypochlorite DROP WISE OVER 10 MINUTES Stir and cool for 20 minutes Test for excess Hypochlorite while stirring a. Use KI starch paper b. Use glass pipette to drop mixture onto strip c. If color changes to blue, excess hypochlorite d. If color does not change, add NaOCl in 5mL increments e. Test after each addition f. Once blue color appears, move on to test #2 Quenching the Reaction while stirring a. Get 10mL saturated sodium bisulfite solution b. Add 4mL of solution to round bottom flask c. Test with potassium iodide starch paper by adding drop of solution to paper d. If paper is white move onto test #3 e. If paper is blue, continue to add sodium bisulfite in 2mL additions and test after each addition Base Wash a. Get 4.5 mL of 6M sodium hydroxide and add to reaction mixture b. Test pH by adding drops of solution to pH strip c. Add base in 1.5 mL additions until pH solution tests basic

Jessie Hays 1/31/19 Thursday 12:30-3:15 TA: Kun Wang

d. Allow to stir for 10 minutes before extraction 10. Extraction a. Add 5mL of dichloromethane to extract the product b. Stop stirring and remove stir bar c. Transfer mixture to separatory funnel d. Extract organic layer e. Add 5mL dichloromethane to aqueous layer and extract organic layer again f. Combine both organic layers extracted. g. Wash with 10mL DI water h. Wash with 10mL of brine i. Dry organic layer with anhydrous magnesium sulfate j. Filter solution into (preweighed) 100 mL beaker with gravity filtration k. Remove solvent using rotary evaporator l. Record mass of product 11. Test FTIR and HNMR spectra of your product...