Draw the following structures.

Question

Draw the structures of the following:

a. A compound with empirical formula C5H8O that gives a positive iodoform test

and does not decolorize KMnO4.

b. A compound with empirical formula C5H8O that gives a positive Tollen’s test and

does not react with bromine water.

c. A compound with empirical formula C5H8O that reacts with 2,4-DNPH,

decolorizes bromine water, and does not give a positive iodoform test.

d. Two geometric isomers with empirical formula C5H8O that give a positive

iodoform test.

Answer 1

OK, so perhaps you can do this by knowing what the tests show that could have the formula: C₅H₈O. First of all, this formula implies that have two double or one triple bond (short 4 Hs for a hydrocarbon or alcohol) or you have a ring and a double bond.

Let's look at the tests:

Iodoform positive: Methyl ketone, 2^°alcoholl

Bromine: C double bond C, C triple C, phenol

Brady's (DNPH) Carbonyl Group

Tollens positive is aldehyde, not ketone (Often after Brady's)

KMnO₄ (Baeyer's Reagent): Tests for CC double and triple (Less limited than Bromine test because aldehydes can react with it.

a) Must be a methyl ketone without a C=C or C≡C. Are you sure about the formula?

b) Aldehyde with no unsaturation. Again, formula seems suspect.

c) Aldehyde or ketone, has some unsaturation, not methyl ketone

d) Methyl ketone (2 of them, move around the double bond between Cs)

I hope that helps. You may have some added facts about the tests from your class notes.