Experiment 24A Prep of 1-methylcyclohexene PDF

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Lab report for experiment 24A...

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Experiment 24A: Prep of 1-methylcyclohexene I.

Abstract:

The purpose of this experiment was producing 1-methylcyclohexene with the reaction among 1-methylcyclohexanol, phosphoric acid, and sulfuric acid, plus heat. The mass of 1-methylcyclohexene was 1.65g with a percent yield of 74.66%. Then, the product was analyzed with the IR, 1 HNMR, 13  C NMR, DEPT, and Bromine test to check the structure and purity of 1-methylcyclohexene. II.

Chemical reaction:

The theoretical yield of 1-methylcyclohexene was 2.21g.

III.

Table of physical constants: Molecular formula + structure

Molecular weight (g/mol)

Melting point (°C)

Boiling point (°C)

Density (g/mL)

1-methylcyclohexanol

C7H14O

114.188

25

168

0.92

Phosphoric acid

H3PO4

97.994

42.4

158

2.20

Sulfuric acid

H2SO4

98.08

10.3

310

1.840

Saturated sodium chloride

NaCl

58.44

800.7

1461

2.17

Anhydrous sodium sulfate

Na2SO4

142.036

884

1429

2.66

1-methylcyclohexene

C7H12

96.173

-12.0

110.3

0.811

IV.

V.

Separation scheme:

Procedure: The procedures on the lab manual were followed.

VI.

Data:

Mass of 1-methylcyclohexanol

2.619g

Mass of 1-methylcyclohexene

1.65g

% Yield

74.66%

Bromine test

Brown to colorless

P ercent yield =

actual yield theoretical yield

× 100%

Percent yield of isopentyl acetate= VII.

1.65 g 2.21 g

× 100% = 74.66%

Conclusion: In this experiment, 1.65g 1-methylcyclohexene was produced with the percent yield of

74.66%. The percent yield was not too high because the reaction might not be completely done. Also, some of the products were not transferred to the conical vial and weighed. In the 1HNMR spectrum, there were major 3 integrations, including 13.41, 56.00, 103.26. Then, divided these numbers to the smallest integration value to find the total Hydrogen number. On the first peak with the integration of 103.26, there were seven hydrogens. On the second peak with the integration of 56.00, there were 4 hydrogens. On the third peak with the integration of 13.41, there was 1 hydrogen. Thus, there were total 12H which matched with the total hydrogens of 1-methylcyclohexene. The product was analyzed with DEPT. The result turned out that in DEPT 45, there were two peaks pointing upwards to show CH and CH3. In DEPT 90, there were four peaks pointing downwards to show four groups of CH2. One peak pointing upward represented the CH. In

DEPT 135, there were six peaks pointing upwards. All of these peaks match with peaks in DEPT 45. Thus, these peaks provided evidence for the structure of 1-methylcyclohexene. Then, the product was analyzed using the 13  C NMR spectrum, there were total of 7 peaks. The four CH2 bonds showed the peaks at 22.196, 22.810, 25.021, 29.765. The peak at 23.378 showed a CH3 bond. Then, the peak at 120.842 showed the carbon had the double bond with another carbon. Lastly, the peak at 133.286 showed the carbon had the double bond with another carbon and single bond with CH3. Overall, this 13  C NMR spectrum showed the structure of 1-methylcyclohexene. Then, the product was analyzed using IR spectrum. 1-methylcyclohexene had typical functional groups of a ring with a double bond, and a methyl group. The peaks at 3002.77 cm-1 and 2963.27cm-1 showed the stretching of H-C in C=C bonds. The peaks at 2924.38cm-1, 2835.05cm-1, 2857.39cm-1 showed the stretching of H-C in C-C bonds. The peak at 1439.04cm-1 showed the C=C bond in the ring. Lastly, the product was tested with the bromine absorption test to check whether it had the double bonds or not. Before testing, 1-methylcyclohexene was brown. When it was mixed with Bromine, the compound changed from brown to colorless. Bromine broke this C=C double bond and attached itself to 1-methylcyclohexene. Because the Bromine was no longer in its elemental form, it could not be seen as brown color anymore. Thus, the bromine test absorption result showed that the product had the double bonds. VIII.

References: 1. “The PubChem Project.” N.p., n.d. Web. 23 Nov. 2018. .  ...