Question

QUESTION 3 Below are the 1H NMR spectrum of isoamyl acetate and the structure (same structure as Q1). The blue fonts represent integrated ration per group of hydrogen(s). The peak at S is due to H5 | H5" H2 H2 H1 H6" H4 H1" H3 H6 4.25 3.95 ppm 17 1.5 1.3 0.9 ppm 1ppm 10 1.00 2.94 2.04 Int: 2.01 6.00 8 H2' 6.H3 07 H4 H3

Answer 1

The peak s is due to which protons can be determined by using the concept of sigma - value. Multiplicity and integrated ration for this peak. Now from the 1H - spectrum, the integrated ration for thispeak is 2.01 Tildeequal 2.0: so the peak is due to two equivalent proton. So there is two possibilities (i) either this peak is due to H-2 & H-2^' ii or this peak is due to H-3 & H-3^' Now let us consider the multiplicity of the peak. Since multiplicity of the peak is triplet, the protons will have two neighboring non - equivalent protons. If it would for H-3 & H-3^', then we would get quartet multiplicity so we can conclude that the peak s is due to H-2 & H-2^' If we consider the sigma - values of that peak we can confirm the peak s due to H-2 & H-2^' only. Since H-2 & H-2^' are attached with the carbon atom which is