Aspirin and Tylenol are brand names for the analgesic drugs acetylsalicylic and acetaminophen, respectively. Despite somewhat different chemical structures and elemental makeup, the drugs nevertheless have similar effects in the body. Both relieve pain, reduce inflammation, and decrease fever. The two molecules have three elements in common with each other, which lead to some of their similarities in structure and function.
Carbon
Organic molecules, meaning molecules of life, are carbon-based. As both acetylsalicylic acid and acetaminophen are organic molecules, they share the common feature of a carbon skeleton. The "CRC Handbook of Chemistry and Physics" describes the shape of an Aspirin molecule as consisting of a single six-membered ring structure, made up of carbon atoms, with two carbon-based arms. The Tylenol molecule, similarly, contains a six-membered carbon-based ring structure, with two carbon-based arms. The six-membered carbon ring is very common in organic molecules, because it's very stable. While the element carbon lends overall shape to both aspirin and Tylenol, this element isn't particularly chemically reactive in either molecule.
Oxygen
Both Aspirin and Tylenol also contain the element oxygen. Aspirin has four atoms of oxygen in its structure, while Tylenol has two. The total number of oxygen atoms in the molecule isn't as important to reactivity as the way in which oxygen atoms are connected to the carbon skeleton. Each molecule has a very reactive oxygen-containing group that lends the molecule acidity. Aspirin's reactive group is called a carboxylic acid, consisting of a carbon, two oxygen atoms, and a hydrogen. Tylenol's reactive oxygen-containing group is called a phenol, and consists of a single oxygen and a single hydrogen atom. Drs. Mary Campbell and Shawn Farrell note in their book, "Biochemistry," that both carboxylic acids and phenols are common in compounds with physiological activity.
Hydrogen
The element hydrogen features prominently in both Aspirin and Tylenol. Aspirin has eight hydrogen atoms, while Tylenol has nine. Hydrogen's ability to react chemically depends greatly upon the elements to which it is bonded--generally, carbon-bound hydrogen is very stable and unreactive. Oxygen-bound hydrogen, on the other hand, can be very reactive, and often leads to acidic properties in molecules. Both Aspirin and Tylenol have oxygen-bound hydrogen atoms, and as such, both molecules are acidic in nature. Drs. Campbell and Farrell note that due to the nature of the specific bonding patterns in the molecules, Aspirin is significantly more acidic than Tylenol.
References
- "CRC Handbook of Chemistry and Physics"; David Lide; 1974
- "Biochemistry"; Mary Campbell, Ph.D. and Shawn Farrell, Ph.D.; 2005
