FUNCTIONAL GROUP IDENTIFICATION WORKSHEET Identify the functional groups on the following organic molecules
The Correct Answer and Explanation is:
Here are the functional groups identified for each molecule:
a. Carboxylic acid (Carboxyl group)
b. Ester
c. Amide
d. Alcohol (Hydroxyl group)
Explanation
Functional groups are specific arrangements of atoms within molecules that are responsible for the characteristic chemical properties and reactions of those molecules. Identifying them is a fundamental skill in organic chemistry, as they dictate how a molecule will behave. This worksheet presents four common organic molecules, each containing a distinct functional group.
a. Carboxylic Acid: The first molecule, ethanoic acid (commonly known as acetic acid), features a carboxyl group (COOH). This group consists of a carbonyl group (a carbon double bonded to an oxygen, C=O) and a hydroxyl group (OH) attached to the same carbon atom. The presence of the carboxyl group classifies this molecule as a carboxylic acid. This functional group is notable for its acidic properties, as the hydrogen on the hydroxyl group can be donated as a proton (H+), making the molecule acidic.
b. Ester: The second molecule is an ester, specifically ethyl ethanoate. The defining feature is the ester group (COO), which can be visualized as a derivative of a carboxylic acid where the acidic hydrogen of the hydroxyl group has been replaced by an alkyl group. It consists of a carbonyl group (C=O) bonded to an oxygen atom, which is in turn bonded to another carbon chain. Esters are widely recognized for their characteristically pleasant and often fruity aromas and are found in many natural and synthetic flavorings and fragrances.
c. Amide: The third structure displays an amide functional group. This group is characterized by a carbonyl group (C=O) directly bonded to a nitrogen atom. In this specific molecule, N ethylpropanamide, the nitrogen is also bonded to a hydrogen atom and an ethyl group, making it a secondary amide. The amide linkage is of immense biological importance as it forms the peptide bonds that link amino acids together to create the primary structure of proteins.
d. Alcohol: The final molecule, 2 butanol, contains a hydroxyl group (OH). When a hydroxyl group is attached to a saturated carbon atom (an sp3 hybridized carbon), the molecule is classified as an alcohol. This polar group allows the molecule to form hydrogen bonds, which significantly affects its physical properties, such as increasing its boiling point and solubility in water compared to a corresponding alkane of similar molecular weight
