Question

Propose a structure given the following information.

Information: Each spectra below was obtained from a pure compound. Mass Spectrum parent peaks (M) are listed for all examples. IR peaks listed are strong is) unless otherwise indicated for signals above 1500 cm 'H NMR Spectra, the integral is given in number of hydrogens (NH) or as a relative ratio. Important coupling constants (-values) are listed next to the peaks for some examples. For some spectra, an inset (grey box) is also given showing a "zoom-in" on an important part of the spectrum. Mass Spectrometry (not shown): (M) = 112 m/z Infrared Spectroscopy (not shown): 2860, 1699 cm 'H Nuclear Magnetic Resonance. PPM "Sc Nuclear Magnetic Resonance. 220 200 180 160 140 120 PPM 100 80 6040 200

Answer 1

Let us start with I.R. spectroscopy 2.860m - C-H stretching alkanes 1699 cm - czo stretching ('3 NMR spectro shows two signals indicates - c- group 2o9ppm 38ppm - indicates SP3 carbon. H NMR spectra shows a singlet for 8H atome BH atoms shows singlet that means these 8H atoms are in same environment. The possibility is presenle op 4 che groups CH₂ CH₂ CH₂ CH2 14 + 14 +14 + 14 = 56 28 we know the poefence of C-o group: This accounts for 28 84 Molecules ion peak is at 7 a 112 so molecules weight is 112 a. mat. 112-84 = 28 a. me

This 28 corresponds to E group. groups 28 also two CH₂ indicates 14 +14 = 2-8 But NMR chows only 8H atoms. so 28 corresponds to į group. groups finally, the compound contains four CH₂ groups & two CH2, Che. Che, che Molecules formula C HBO2 Double Bond Equivalents CD.BE) = Not1- NH NX + NN- No of c atom No H atoms No. of halogens No op N atoms = 6+1 - 8 = 7-4 = 3 a bordialready we have two double bonds (two czo groups) D.B.E value of 3 indicate the prepence of one more double bond or a ring. from H NMR & C NMR, no other double bond is present.

so sing is present since all cha groups are same the possible units are CH-_ che & -che- & - CH2 these two units By we combining get - E-clla : The structure of compound is 2-> 2.7, 8, singet 2o8ppm. 1699 cont 1,4 Cyclohexane fone = =