Question

Question 2 (25 pts.) This is benzoic acid. Draw MINOR RESONANCE contributors as necessary to explain why the nmr chemical shift of carbon A is larger than that of carbon B. Give a brief explanation that includes the terms "deshielding" and "electron density. Question 3 (18 pts.) Rank the indicated hydrogens A, B and C in order of INCREASING chemical shift, give a BRIEF explanation. You do not need to invoke resonance to answer this question. lowest highest Question 4 (23 pts.) For the following reaction: a) Add the curved arrow pushing that describes bond making and bond breaking b) Identify the Lewis acid base (LALB) and whether they are also Bronsted acids/bases (BA/BB) c) Draw the transition state d) State whether you would expect the reaction to be exothermic or not and BRIEFLY explain why H2C-o: + H-C-Br: O-C-H 3 HEC Extra Credit (5 pts.) Which kind of analytical instrument is used to detect explosives at security screenings at airports? infrared spectroscopy mass spectrometry NMR spectroscopy

Answer 1

C.Ron 9 Solution 7 - -COom poup is a -I group which will draw elettron donsity from benzene ring so that the election clensity is higher at B than a so pin a present at B is more shielded than A so that the chemical shift of A is larger than that of carbon Bo Solution (3) (wn-lo-(m.)- пс Order of chemical shift is given as CL ALB lowest highest Explanation Electronegativity of oxygen is more than Nitrogen so that B is the most deshielded hence highest chemical shift value. c is present at the largest distance so it is most shielded hence lowest value Scanned with CamScanner