Predicting^1H-NMR chemical shift and splitting pattern for a known structure. Hy
ID: 479331 • Letter: P
Question
Predicting^1H-NMR chemical shift and splitting pattern for a known structure. Hydrogenation converts propanone into 2-propanol. Could^1H-NMR spectroscopy tell you if the reaction was successful? Could^13C-NMR be used? Could IR spectroscopy be used? For each technique which could be used, be specific, highlight the ONE most significant difference (chemical shift, integration, splitting pattern, absorption, coupling constant) between starting material and product. 1H-NMR: 13C-NMR: IR: You have a sample of a compound which may be either 1-hexanol or 2-hexanol. Could you tell which it is by^1H-NMR spectroscopy? By^13C-NMR? For each technique which could be used, be specific, highlight the ONE most significant difference (chemical shift, splitting pattern, integration, absorption, coupling constant) between the compounds. 1H-NMR: 13C-NMR: Describe how you could use^1H-NMR to distinguish between the following pairs of molecules. Be specific, highlight the ONE most significant difference (chemical shift, integration, splitting pattern or coupling constant between the compounds. If^1H-NMR cannot distinguish between the pair, record "not possible."Explanation / Answer
1) propanone on hydrogenation gives 2 propanol
the conversion or reaction progress can be check by using 1H NMR,13C NMR and IR also.for distingushing both take NMR of propanone for 1H NMR we get high intense single peak for 6 protons (Singlet) with 2.03 delta value,in 13C NMR we get only two peaks for three carbon atoms out of that two CH3 groups are from same chemical environment so they will show single peak for CH3 around 30 delta value,and one peak for carbonyl carbon with delta value around 201,this peak is absent in product .If we took IR for propanol we get carbonyl frequency around 1620 cm-1.
for product 2-propanol 1H NMR show three peaks for -OH (3.5delta exchangable) ,-CH3(1.03 delta doublet),and -CH.groups.(3.2delta multiplate).in 13C NMR we get only two peaks at 30delta for two -CH3 groups and 65delta for one -CH of alcohol group.the IR will give broad peak at 3300-3500 cm-1 for -OH group.which is not observed in propanone IR.
In this way we can distingush both the compound on the basis of spectra.
Note- chemical vaues are Not exact,nearby only.)
Same way consider 1 hexanol and 2 Hexanol both in 1H NMR gives seven peaks ,but the main difference peak obtain in 2-Propanol is,giving doublet for one -CH3 group which is not obtain in 1-Propanol compound NMR.if we take 13C NMR then we get equal peak in both the spectra only difference between them is the chemical shift value of carbon atoms.the 2-propanol having higher chemical shift value of carbon ex. -CH of alcoho will came at 69 delta.while in 1-propanol the carbon delta values are less ex.-CH2 of alcohol came at 59 delta..IR will not help better distngush.