Question

LOD 50 1500 1000 S00 3000 2000 4000 HAVENUMBERI- TANSHETTANCEI% Data Analysis: IR Spectra The below information is what I have so far. I am having |difficulty in figuring out the structure that fits the provided IR spectra. The IR spectra provided literally matches exactly to 2-methylhexane (C7H16), but that does not match the molecular formula given to me by my professor. Any help would be greatly appreciated! Name 1. Unknown code Molecular formula C7H14 2 (2(7)+2-14)/2 = 1 DoU 3. Calculate U 4. List the important (diagnostic) peaks from the IR spectrum below according to the region given. List the cm and the bond that corresponds to each peak. sp3 C-H stretch from 2850 to 2950 cm^-1 C-H bending from 1350 - 1475 cmA-1. DoU indicates presence of one ring or 1 double bond. List any important (diagnostic) peaks that are absent from the IR spectrum 5. List any classes of compounds that fit the data (i.e., aldehyde, alcohol, ketone) 6. alkyl? 7. Propose a structure that fits the data. Are any structural isomers available? Draw at least one additional structural isomer.

Answer 1

Since this is a hydrocarbon (only C and H) and degree of unsaturation is 1, this can either be an alkene or cycloheptane.

In case of alkene, the following peaks are observed:

(i).A medium peak at 3000-3100 cm^-1 due to C-H stretch,

(ii).A medium to weak peak in the range 1650-1650 cm^-1 due to C=C

But the above peaks are absent in the given IR spectrum. Hence this structure cannot be any one of the alkenes.

#4: Important peaks from IR spectrum:

(i). sp3 C-H stretch in the range 2850-2950 cm^-1 indicates that all the carbons are sp3

(ii): sp3 C-H bending in the range 1350-1475 cm^-1 due to all the sp3 carbons.

Since there is no peak for sp2 carbon, alkene is absent.

#5: None of them are absent.

#6: Since this is not an alkene and all the carbons are sp³, this must be cycloheptane or its structural isomers.

Hence the class of compound is cycloalkane.

#7: The most probable molecule is cycloheptane whose structure is given below:

(Cycloheptane, C7H14)

Some of the structural isomers are shown below:

CH3 CH3 CH3 CH3 C7H14 C7H14 C7H14 CH3