Question

5. Examine the attached 'H NMR spectrum of the product that you are making today. What significant difference(s) are present (with respect to the spectrum of the dibromide product)? 6. For today's experiment, we are doing a reaction with trans-cinnamic acid using NBS (which effectively provides a dilute solution of bromine) in a mixture of water and methanol. Predict the four possible products of this reaction. Note the dibromide product is not a possibility here. (See question 2). For this question, we are looking at regioisomeric products (not stereoisomers). Br-N оно H20, MeOH

Answer 1

5) The product has two doublets due to alkene protons (dibromide as shown below), one singlet due to COOCH3 (methyl protons integration 3), and 5 protons multiplet due to aromatic benzene ring. The main difference between product and reactanta are i) more downfield shift of alkene protons compared to dibromide product protons ii) additional 3 proton singlet due to ester methyl group, iii) disappearance of carboxylic acid proton near 12 ppm.

6) as mentioned in question we can expect following products. They clearly mentioned that product is not dibromide, so NBS/water system can provide bromohydrin (Br-OH) molecule addition across double bond.

o obte - Olte Reactant ale doconfield dibromide (Product) (+3) ase shielded cup field) BY O CH3 OCH OCH IN

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