Question

Draw structures for compounds that meet the following descriptions:

(a) C₂H₆O ; one singlet

(b) C₃H₇CI ; one doublet and one septet

(c) C₄H₈CI₂O ; two triplets

(d) C₂H₈O ; one singlet, one triplet, and one quartet

Short answer

If the nearby atom does not contain a hydrogen, the resonance stays as a single peak and is termed a singlet. If one hydrogen is present on the nearby atom, the resonance splits into two peaks and is termed a doublet.

Step-by-step solution

Splitting patterns

If the nearby atom does not contain a hydrogen, the resonance stays as a single peak and is termed a singlet. If one hydrogen is present on the nearby atom, the resonance splits into two peaks and is termed a doublet.

Structure of various compounds that meet the given description

(a)The double bond equivalence for the formula C₂H₆O can be found as:

Here double bond equivalence is 0. Hence no double bond is present in this compound.

Since there is only one peak, the hydrogen atoms are not adjacent to each other. The molecule is symmetric and the possible structure is given as:

Structure of compound a

The structure has two carbon atoms, six hydrogen atoms and one oxygen atom.

(b)The double bond equivalence of the formula C₂H₇CI can be given as:

Here double bond equivalence is 0. Hence no double bond is present in this compound.

One septet indicates the presence of six equivalent hydrogen atoms on the neighbouring carbon atoms. One doublet indicates the presence of one hydrogen atom on the adjacent carbon atom. The possible structure can be given as:

Structure of compound b

(c)The double bond equivalence for the formula C₄H₈CI₂O can be given as:

The double bond equivalence is 0. Hence the compound does not have a double bond.

There are two peaks and both of them are triplets. So there is a degree of symmetry for the molecule. There cannot be a terminal -CH₂ group or there would be a quartet. So the chloro group must be on the terminal carbons. For the molecule to be symmetric, the oxygen will be in the center position. The structure can be given as:

Structure of compound c

(d)The double bond equivalence of the formula C₄H₈O₂can be given as:

Here, the double bond equivalence is one. Hence the compound contains one double bond.

There is one singlet, so there is a terminal carbon that has no neighbouring carbon. This indicates a methyl group connected to the oxygen which has a carbonyl group as the neighbor. The ethyl group is also connected to the carbonyl group. This gives a quartet and a triplet. The possible structure can be given as:

Structure of compound d