Q. What is the name of this unknown compound? Additional info: Unknown compound

Question

Q. What is the name of this unknown compound?

Additional info: Unknown compound was insoluble in all solvents (water, ether, NaOH, NaHCO3, HCl and H2SO4). During the bromine/methyl chlodride test there was no decolorization indicating a negative test. The Baeyer test was negative and the aluminium chloride/chloroform test was positive. The refractive index was 1.4973 @ 20 degrees celsius. During distillation the boiling point of the first 10 drops was 68.4-84.1 degrees celsius, and the rest of the distillate was at a range of 85.3-137.2 degrees celsius.

No molecular formula was provided.

Explanation / Answer

This is an FTIR spectrum . FTIR is not generally used to determine the structure of an unknown compound. But it can be used to determine the various functional groups present in it.

Hydrocarbons show IR absorption peak between 2800-3300 cm-1 is due to C-H stretching vibrations.The hybridisation of the carbon affects the exact position of the absorption-stiffer bonds.

Sp3 C-H is between 2800-3000cm-1

Sp2 C-H is between 3000- 3100 cm-1

Sp C-H is in 3300 cm-1

Here peak is at 2921cm-1 . So it is Sp3 C-H.

C=C is present at 1613 cm-1 represents arenes. Peak at 1492 cm-1 represents the C-C stretches in the aromatic ring.

Strong peak at 766cm-1 represents mono or ortho substituted C-H bonds in the aromatic ring.

The refractive index given here is 1.497 which is corresponding to ethyl benzene.

Since the compound is insoluble in all solvents, and bromine/ chloroform test gives positive results,we can assume that the unknown compound can be ethyl benzene.Since it gives negative results for Baeyer test,it can be confirmed as ethyl benzene.

Hence the answer is ethyl benzene (C6H5C2H5).

Related Questions

Navigate

• Browse (All)
• Browse Q
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.