NMR Interpretation

NMR Interpretation

1. NMR Interpretation
Prepared By :
Mahendra G S
M-Pharm,Pharmaceutical
Chemistry
JSSCP, MYSURU

3. Splitting Patterns of Common Multiplets
Number of equivalentAppearanceIntensities of lines
protons to which H of multipletin multiplet
is coupled
1 Doublet 1:1
2 Triplet 1:2:1
3 Quartet 1:3:3:1
4 Pentet 1:4:6:4:1
5 Sextet 1:5:10:10:5:1
6 Septet 1:6:15:20:15:6:1

4. Degree of unsaturation
Becauseofthepresenceofadoublebond,alkeneshave
twofewerhydrogensthanthecorrespondingparent
hydrocarbon.
Forexample,ethene(H
2C=CH
2)hasthemolecular
formulaC
2H
4andethane(CH
3CH
3)hastheformula
C
2H
6(followingthe2n+2rule).
Cycloalkanes,likewise,havetwofewerhydrogen'sthan
theparenthydrocarbonsincetwoofthevalencesare
utilizedtoclosethering:cyclohexaneisC
6H
12,while
hexaneisC
6H
14.

5. Knowingthisrelationship,itispossibletotakeamolecular
formulaandcalculatethedegreeofunsaturation;thatis,the
totalnumberofmultiplebondsorringsinamolecule.
Thisinformationcanthenbeutilizedintheconversionof
analyticaldataintostructuralpossibilities.
Forhydrocarbons,theprocessissimple:
taketheparenthydrocarbonandcalculatethenumberof
hydrogensusingthe2n+2rule,
everytwohydrogensthatare"missing"intheanalysisofthe
unknownrepresentsonedegreeofunsaturation(DU).

7. 1. number of signals
2. their intensity (as measured by area under peak)
3. splitting pattern (multiplicity)

8. 2-pentanone, C5H10O

22. 3-methylaniline

26. 4-t-butylbenzoic acid

28. 5-methyl-2-isopropylphenol
also known as thymol

32. 3-butyl pyridine