Question

• A urugens are located within an unresolved cluster of peaks the methyl peaks can e chemical shifts (higher field). However, even when methyl ognized as tall singlets, doublets, or triplets clearly emerging from the a types of protons. Methine protons are usually separated from the doublets, or triplets clearly emerging from the absorptions of the other further downfield. nine protons are usually separated from the other protons, being shifted Figure 3.57 shows the spectrum of the bu Note that the integral can be to estimate the total number of hydrogens (the ratio of CH, to CH-type can hydrogens (the ratio of CH, to CH-type carbons) because all of 1241 aba CHCHCH, PEFC FIGURE 5.37 'H spectrum of octane (300 MHz).

can someone explain this H NMR spectrum why does b not follow the n+1 rule is it do to symmetry? can someone explain this concept to me

Answer 1

Proton H-NMR shows two types of protons only in place of four required signals this is due to the fact that for recording 300 MHz instrument has been used . So shimming has not taken place properly in the instrument, this problem can be fixed by using either 400 or 600 MHz more efficient NMR instruments. This problem arises because of the fact that they are almost in same chemical environment which prevents them spiltting properly or following the N+1 rule. Besides,  -CH₃ triplet is also not very clear. Some times poor shimming or not observing the proper splitting pattern could also be more concentration of the compound taken for NMR recording.....this is the most common reason for poor splitting.