A2. What is the molecular formula consistent with the following mass spectrum da

Question

A2. What is the molecular formula consistent with the following mass spectrum data? M-at mZ-108, relative height-61.5% (M + 1 ).. at ritz 1 09, relative heights 1.5% (M +2).. at mate 1 1 0, relative height:61.3% A3. Propose a possible structure for a compound with molecular formula C,H202 that shows absorption at 1720 cm1 and no absorption in the range of 1500-1700 cm1 or 2600-2800 cm in its IR spectrum. B. Hydrogen Deficiency Index What is the HDI in each of the following molecules? CsH,Br NO C1HeCIBrO CH,Br CgHsBr CoH,INO c. NMR Spectroscopy C1. Indicate the number of H NMR peaks that would be observed for the following compounds.

Explanation / Answer

A1. Assuming M+ ion peak to be 100% abundance, then M+1 peak would be 2.44% based on the ratio [61.5 : 1.5]

also then M+2 peak would be 99.7%

Since m/z value is even, number of nitrogen will also be even, may be zero or 2

The relative abundance of M+1 gives you the number of Carbons in the molecular formula. We get the number of carbons by dividing the relative abundance by 1.1%

So 2.44% by 1.1 % = 2.21

It means we have 2 carbons

- If the M+2 relative abundance is: ~4 % then a Sulfur is present

~33% then a Chlorine is present

~100% then a Bromine is present -

If the M+2 relative abundance is not near any of these numbers then there is none present. Since we have M+2 % abundance closer to 100, it means Bromine is present.

Since one Br atoms contributes to m/z 80, 108- 81 = 27 m/z

2 carbons = 2 * 12 = 24

So remianing [27-24= 3] can be contributed by hydrogens

So molecular formula would be CH2=CH-Br

If you need help with rest of the problems please submit them as separate problems

Thank you !

Diving M+1 peak percentane abundance by 1.1% gives # of carbons

So 2.44/1.1 =

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