Problem 6 Atomic and molecular orbitals - PianetaChimica.it

33 rd International Chemistry Olympiad ∗ Preparatory Problemsf. Give appropriate structures for B and C.g. What is the difference between the reactions leading to the formation of A andB?h. Why is the yield of C higher than that of B?Problem 17 Organic spectroscopy and structure determinationThe following observations were recorded for identifying two compounds A and B.Both have the molecular formula C 3 H 6 O. Schematic 1 H-NMR spectra of thesecompounds at 400 MHz are presented in the following figure. The peak positions andthe relative intensities of the different lines in the 1 H-NMR spectrum of B are given inthe accompanying Table (Note: the values have been altered slightly from theexperimental values to facilitate analysis.)One of these compounds reacts with malonic acid to form a compound known asMeldrum's acid, with the molecular formula C 6 H 8 O 4 , which gives peaks between 0 and7.0 δ in its 1 H-NMR spectrum. The IR spectrum shows a peak in the region 1700 - 1800cm -1 . It condenses with an aromatic aldehyde in the presence of a base.AB765 4 3 2chemical shift (δ)101 H-NMR schematic spectra of A and B at 400 MHzMumbai, India, July23 23