Q56E - Organic Chemistry (Mcmurry)

Question

Give IUPAC names for the following compounds:

(a)

(b)

(c)

(d)

(e) 

(f) 

Step-by-Step Solution

Answer

(a) 3-Methyl-3-cyclohexenone

(b) (R)-2,3-Dihydroxypropanal (D-Glyceraldehyde)

(c) 5-Isopropyl-2-methyl-2-cyclohexenone

(d) 2-Methyl-3-pentanone

(e) 3-Hydroxybutanal

(f) p-Benzenedicarbaldehyde

Step 1: Naming Aldehydes and Ketones

Aldehydes and ketones are named by replacing the ‘e’ of alkane with ‘al’ for aldehydes and ‘one’ for ketones. If the parent chain contains the –CHO group, it ends with ‘-al’, and if the parent chain contains ‘R-C=O,’ it ends with ‘-one.’

The IUPAC name of compound (a)

(a) The given compound has a parent cyclic chain that contains the ketone group. The numbering starts from the carbon to which the ketone group is attached. At the 3^rd position, a methyl group and double bonds are present. The cyclic chain consists of 6 carbon and is named ‘cyclohexene.’ The name ends with –one because of the ketone group. Thus, the IUPAC name of the compound is 3-Methyl-3-cyclohexenone.

  3-Methyl-3-cyclohexenone. 

Step 3: The IUPAC name of compound (b)

(b) The given compound has a chiral carbon in which all four groups are different. The configuration of this carbon is ‘R’ means clockwise. The numbering starts from the top because of the aldehyde group. At the 2^nd and 3^rd positions, hydroxyl groups are present, and ‘Di’ is used. The chain consists of three carbons and is named ‘propane,’ The name ends with –al because of the aldehyde group. Thus, the IUPAC name of the compound is (R)-2,3-Dihydroxypropanal (D-Glyceraldehyde).

(R)-2,3-Dihydroxypropanal (D-Glyceraldehyde)

Step 4: The IUPAC name of compound (c)

(c) The given compound is a 6-membered ring having a ketone group attached, and the name of this ring is ‘cyclohexenone’. At 2^nd, a methyl group is attached, and at the 5^th position, an isopropyl group is attached. A double bond is present at 2^nd carbon. Thus, the IUPAC name of the compound is 5-Isopropyl-2-methyl-2-cyclohexenone.

5-Isopropyl-2-methyl-2-cyclohexenone

Step 5: The IUPAC name of compound (d)

(d) The given compound has a five-carbon parent chain containing a ketone group at 3^rd position, and the name given to the chain is ‘pentanone’. At 2^nd, a methyl group is attached. Thus, the IUPAC name of the compound is 2-Methyl-3-pentanone.

        2.-Methyl-3-pentanone

Step 6: The IUPAC name of compound (e)

(e) The given compound is a four-carbon parent chain containing an aldehyde group at 1^st position, and the name given to this chain is ‘butanal.’ At the 3^rd   position, hydroxy group (-OH) is attached. Thus, the IUPAC name of the compound is 3-Hydroxybutanal.

                      3-Hydroxybutanal

Step 7: The IUPAC name of compound (f)

(f) The given compound contains a benzene ring. The two aldehyde groups are present at para positions. Thus, the IUPAC name of the compound is p-Benzenedicarbaldehyde.

    p-Benzenedicarbaldehyde