This means structures of this sort oh ho n n problem

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: re trying to decide which is which. In what ways would 13C NMR data help? (a) One sharp band above 3000 cm–1 and one strong band at about 1700 cm– 1 (b) Two sharp bands above 3000 cm–1 and two bands between 1600 and 1700 cm–1 (c) One strong broad band above 3000 cm–1 and a band at about 2200 cm–1 Purpose of the problem To show that IR alone does have some use but that NMR data are usually essential as well. In answers to exam questions of this type it is important to show how you interpret the data as well as to give a structure. If you get the structure right, this doesn’t matter, but if you get it wrong, you may still get credit for your interpretation. Suggested solution (a) One sharp band above 3000 cm–1 must be an N–H and one strong band at about 1700 cm–1 must be a carbonyl group. That leaves C2H4, so we might have one of the structures shown below, though other less likely structures are possible too. 13C NMR data would help as it would definitely two types of saturated carbon (along with the carbonyl group) for the first compound, but only one for the second. H N O O NH (b) Two sharp bands above 3000 cm–1 must be an NH2 group and two bands between 1600 and 1700 cm–1 suggest a carbonyl group and an alkene. This leaves us with three hydrogen atoms so we must have something like the molecules below. 13C NMR data would help as it would show an alkene carbon shifted downfield by being joined to electronegative nitrogen in the second...
View Full Document

Ask a homework question - tutors are online