The Conversion of Benzaldehyde to Benzilic Acid

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Spectra Analysis

Organic Chemistry Lab, CHEM 369

The University of Tennessee, Knoxville

Dr. Smith

Spectra 1: tert-butyl cyanoacetate

Molecular formula:

141/13 = 10 R 11 => C10H10+11 => C10H21
C10H21NO2 – C3H10 = C7H11NO2

DBE:

2(#C - #H/2 - #X/2 + #N + 2)/2 =2(7 – 11/2 – 0/2 + 1 + 2)/2 = 3=> 1 double bond and 1 triple bond

Mass spectrum table:
m/zfragment
|40 |C3H5+ | |57 |C4H9+ | |115 | | |126 | | |141 | |

IR spectrum table:
Peak (cm-1)bond vibration
|2983, 2936 |C-H | |2262 |C≡N | |1744 |Ester carbonyl | |1460 |C-H | |1145 |C-O |

H-NMR spectrum table
shift (ppm)integrationH-groupmultiplicityneighboring H
groups
|1.5 |9H |Three -CH3 |singlet |(CH3)3C | |3.4 |2H |-CH2 |singlet |CH2 |

C-NMR spectrum table
shift (ppm)Possible carbon groups with shielding/deshielding |161.8 |OOC-CH2 | |113.4 |N≡C-CH2 | |84.3 |(CH3)3-C | |27.7 |(CH3)3-C | |25.8 |C-CH2-C | | | |

Summary

The IR peaks at 2983 and 2986 result from C-H bond stretches. The peak at 2262 corresponds with a nitrile group. The peak at 1744 indicates an ester carbonyl group is present. The molecular formula was found to be C7H11NO2 and the name is tert-butyl cyanoacetate. [pic]

Spectra #2 4-methylbenzoic acid

Molecular formula:

136/13 = 10 R 6 => C10H10+6 => C10H16
C10H16 OO – C2H8 = C8H8O2

DBE:

#C - #H/2 - #X/2 + #N + 1 = 8 – 8/2 – 0/2 + 0 + 1 = 5 => it contains a benzene ring (1 ring and 4 double bonds)

Mass spectrum table:
m/zfragment
|91...
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