Question

You have the following spectra of the following omethyl benzene 1,2-dimethylbenzene 1,3-dimethyl benzene 1,4-dimethylbenzene Choose which is suitable for each of the following spectra

you have the following spectra of the following compounds

choose which is suitable for each the following spectra

Answer 1

• For methyl benzene :

Aromatic C–H stretching peak 3100-3000 cm-1 [overtones peak 2000-1665 cm-1(lower intensity)]

C=C stretching (in ring)1600-1585 cm-1

C–C stretching (in ring) from 1500-1400 cm-1

C–H bending 1000-1050 cm-1 (bending in plane)

C–H bending 700-750 cm-1 (bending out of plane)

Therefore , 3rd spectrum is for methyl benzene

• For 1 2 dimethyl benzene :

Aromatic C–H stretching peak 3100-3000 cm-1

[overtones peak 2000-1665 cm-1(lower intensity)]

C=C stretching (in ring)1600-1585 cm-1

C–C stretching (in ring) from 1500-1400 cm-1

C–H bending 850-900 cm-1

Therefore , 2nd spectrum is for 1 2 dimethyl benzene

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• ​​​​​​​For 1 2 dimethyl benzene :​​​​​​​

Aromatic C–H stretching peak 3100-3000 cm-1 (shows higher transmitency)

[overtones peak 2000-1665 cm-1(lower intensity)]

C=C stretching (in ring)1600-1585 cm-1(broadening spectrum)

C–C stretching (in ring) from 1500-1400 cm-1 (broad spectrum)

C–H bending 850-900 cm-1

C–H bending 750-850 cm-1

Therefore , 1st spectrum is for 1 3 dimethyl benzene