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LAB REPORT by

NAME _____WU HAO__________ Student ID _____B6SB4702__________

Experiment Ch.12 Synthesis of 6,6-Nylon from Cyclohexene

Experiment Date ______2018/10/22_________ Submit Date ______2018/12____________ Partner ______－－_______________

Instructor’s Comment (コメント):

1. Introduction A large quantity of heavy metals, such as manganese and chromium, are frequently consumed in the conventional methods for oxidizing organic compounds. Recently, new reactions using no heavy metals have been developed to reduce pollution. Such a new field concerning environmentally-friendly chemistry is often known as “Green Chemistry”. In this experiment, cyclohexene will be oxidized to adipic acid with hydrogen peroxide while tungsten used as a catalyst. Nylon is a family of synthetic polyamides produced by condensation between diamines and dicarboxylic acids. Synthetic polymers, including nylon, are made of thousands of repeating units. Nylon can be used in bearings and gears due to its high strength, rub resistance and lubricity. In addition, nylon fibers are extremely durable and used in many fabrics, including stockings, clothes,etc. In this experiment, 6,6-Nylon is to be synthesized by interfacial polymerization between adipic acid and 1,6-diaminohexane.

2. Synthetic routes

3. Experimental

3.1 Objectives (a) Synthesizing 6,6-Nylon using the interfacial polymerization method; (b) Understanding the mechanisms of making synthetic polymers.

3.2 Materials (a) Instruments 100 mL beaker ×1

Kiriyama funnel ×1

200 mL beaker ×1

Test tube with ground joint ×1

300 mL beaker ×1

Glass rod ×1

Allihn condenser ×1

Test tube with side arm ×1

Filter paper ×1 Clamp ×1

Stirrer bar ×1 Thermometer ×1

100 mL Round bottom flask with ground joint ×1 Drying tube filled with CaCl2 with ground joint ×1 Magnetic stirrer including hot plate ×1 (b) Reagents Cyclohexene, 30% hydrogen peroxide, sodium tungstate dihydrate, oxalic acid dihydrate, 1,6-diaminohexane (50% aqueous), sodium hydroxide, thionyl chloride, dimethyl formamide, hexane, and 5% aqueous hydrochloric acid.

3.3 Procedures & Observations

Day 1 of synthesis: Stage 1 of preparation of adipic acid from cyclohexene1. Time 13:20

Operations To a 100 mL round bottom flask with a stirred

Notes/Observations m(Na2WO4·2H2O)=0.509 g

bar, around 0.5 g of sodium tungstate

m((CO2H)2·2H2O)=0.201 g

dihydrate and 0.2 g of oxalic acid dihydrate

V(30% H2O2(aq))=15 mL

were added first, and then 15 mL of 30% 1 Refer to above Theory part for the synthesis scheme.

hydrogen peroxide, where the solid was dissolved by stirring at room temperature. 3.0 mL of cyclohexene was added to above solution; A small amount of vaseline was placed on the joint of an Allihn condenser 13:35

before attached to the flask, and the top of it was stuffed with cotton. The flask was immersed

in

the

water

bath

(with

a

thermometer) as instructed in the set up. The reaction began by increasing the

Bubbles were observed at

temperature to 90℃ with vigorous stirring,

the beginning of the reaction.

which was kept for over three hours. After 13:50

three hours, the heating and stirring were

Small white crystals formed

stopped, and the vessel was taken out of the

were

water bath; the solution was stirred while

reaction vessel after a while

cooling for leaving overnight.

of cooling.

observed

in

the

Day 2 of synthesis: Stage 2 of preparation of adipic acid from cyclohexene. Time

Operations The Allihn condenser was removed from the

Notes/Observations During cooling, many tiny

13:03

flask first, and the crystals was grown by

white crystals precipitated at

cooling with ice for about 30 minutes. Above obtained crystals were collected by

the bottom of the flask.

13:30

filatration on a Kiriyama funnel, then washed

13:50

with few drops of cold water. After transferring the adipic acid product to a

The product obtained was

labeled bottle, it was dried in a vacuum

white solid. And the yield

desiccator for overnight.

equals to the weight of empty bottle+product

minus

the

weight of empty bottle, which is 17.293 g-15.402 g=1.891 g (wet weight).

Dry weight: 17.103 g-15.402 g=1.701 g. Day 3 of synthesis: Synthesis of Nylon by interfacial polymerization2. Time

Operations

Notes/Observations

Around 1.0 g of above synthesized adipic acid was measured and transferred into a 13:05

test tube with ground glass joint, then 1.4 mL

m(adipic acid)=1.006 g

of thionyl chloride and one drop of N, N-

V(SOCl2(aq))=1.4 mL

dimethylformamide were added in fume hood. A drying tube was attached to the test tube, and the flask was heated to 60-70℃ in the

Several

minutes

heating,

acidic

after

gas

with

strong smell was produced 13:30

water bath from 13:34 for around 20 minutes. During the reaction, the inner wall of the test tube was washed with the liquid to fully react.

(HCl(g)), and there was a liquid phase observed on the bottom of the test tube.

The heating was stopped and the reaction

14:00

mixture was left for cooling to r.t., during

The

reaction

mixture

cooling 50 mL of water and 0.5 g of sodium

obtained

after

heating

hydroxide were added to 2 mL of 50%

stooped appeared a light

hexane-1,6-diamine aqueous solution in a

yellow color.

200 mL beaker. While pouring the hexane

14:12

The cooled reaction mixture was dissolved

solution,

a

thin

film

of

with 50 mL hexane in a 100 mL beaker, then

polymers was formed at the

poured slowly into the aqueous diamine

interface

between

two

solution in the 200 mL beaker.

separated

(aqueous

and

organic) layers. The center of the polymer film formed at the 14:15

interface

was picked

up

14:34

tweezers, winded around a test tube. Obtained polymer above was neutralized in

2 Refer to Scheme 2 in the Theory part above.

carefully

The polymer film winded had

with a slightly impure white color.

about 50 mL of 5% hydrochloric acid, then washed vigorously with water to remove the impurities. The washed polymer was dried completely by spreading and compressing with a Kim 14:38

towel. After drying, the polymer was weighed and the waster solution was dumped in the

Dry weight of nylon polymer product: 2.859 g.

green tank.

4. Raw Data (1) Synthesis of adipic acid. Day 1: m(Na2WO4·2H2O)=0.509 g;

Day 2: Adipic acid

m((CO2H)2·2H2O)=0.201 g;

Wet weight: 1.891 g;

V(30% H2O2(aq))=15 mL.

Dry weight: 1.701 g.

(2) Synthesis of nylon. (Day 3) m(adipic acid)=1.006 g, V(SOCl2(aq))=1.4 mL; m(nylon polymer)=2.859 g (dry weight).

5. Results & Discussion (1) The synthesized nylon was submitted to the teacher, also due to the degree of polymerization n is known for the nylon polymer, it is difficult to calculate the percent yield of this experiment.

(2) Suggest mechanisms for the epoxidation of cyclohexene under acidic condition and for the Baeyer-Villiger lactonization of 2-methylcyclohexanone using peroxide under acidic condition. Answer: ① Epoxidation of cyclohexene:

② Baeyer-Villiger lactonization:

(3) Explain the mechanisms for the acid chloride synthesis and the nylon synthesis using Vilsmeier reagent. Answer:

(4) Discuss the advantage of the oxidation reaction conducted in this chapter compared to the conventional oxidations using chromium oxide or nitric acid (ref. 2) from the viewpoint of environmental harmony. Answer: Compared to the corrosive conditions provided by conventional methods of synthesizing adipic acid using either chromium oxide or nitric acid, the solvent- and halide-free oxidation of cyclohexene using 30% hydroxide is clean, safe and

reproducible3. Also, this “green” method involves a series of advantages that contribute to environmental harmony4: ① The hydrogen peroxide (H2O2) is a green oxidant easy to handle and produces only water as a byproduct of the reaction; ② The sodium tungstate used in catalytic amounts is of low toxicity, which is also recyclable (can be used several times); ③ This approach is industrially applicable in laboratory scale experiments both at miniscale an microscale.

6. References Louis Fieser, Kenneth L. Williamson. Organic Experiments. 8th ed. Maruzen publishing Co., Ltd., p.237 & 467. K. Sato, M. Aoki, R. Noyori. (1998). Science, 281, 1646-1647. Lab Textbook (Ch.1-13). (2018). pp.69-73. By Department of Chemistry, Tohoku University.

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K. Sato, M. Aoki, R. Noyori. (1998). Science, 281, 1646-1647. Joaquín Isac-García et al. (2016). Experimental Organic Chemistry. Academic Press, Chapter 13.1....