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Is Adipic Acid Polar or Nonpolar? A Guide for Chemistry Students

05/04/2023

Introduction: What is Adipic Acid and Why Does Polarity Matter?
Adipic acid is an organic compound that has the formula C6H10O4. It is a white crystalline solid that is used to make nylon, plasticizers, and other products. Adipic acid is also a dicarboxylic acid, which means it has two carboxyl groups (-COOH) attached to its carbon chain. The polarity of adipic acid is an important property that affects its solubility, melting point, and reactivity. In this article, we will explain what polarity is and how to determine if adipic acid is polar or nonpolar.

Polarity: What Does It Mean and How to Measure It?

Polarity is a measure of how evenly the electrons are distributed in a molecule. A molecule is polar if it has a partial positive charge on one end and a partial negative charge on the other end. A molecule is nonpolar if it has no net charge or if the charges are evenly balanced. One way to measure the polarity of a molecule is to use the electronegativity values of the atoms that make up the molecule. Electronegativity is a measure of how strongly an atom attracts electrons. The difference in electronegativity between two atoms determines how polar their bond is. The greater the difference, the more polar the bond.

Adipic Acid: Polar or Nonpolar?

To determine if adipic acid is polar or nonpolar, we need to look at its molecular structure and its bonds. Adipic acid has a symmetrical structure with two carboxyl groups on each end and four methylene groups (-CH2-) in the middle. The carbon-carbon and carbon-hydrogen bonds in adipic acid are nonpolar because the electronegativity difference between these atoms is very small. However, the carbon-oxygen and oxygen-hydrogen bonds in the carboxyl groups are polar because the electronegativity difference between these atoms is large. The oxygen atoms have a higher electronegativity than the carbon and hydrogen atoms, so they pull the electrons closer to themselves, creating a partial negative charge on the oxygen and a partial positive charge on the carbon and hydrogen. This means that each carboxyl group has a net dipole moment, which is a measure of the overall polarity of a group of atoms.

The dipole moments of the two carboxyl groups in adipic acid are not exactly opposite to each other, because they are not aligned along the same axis. This means that they do not cancel out completely, and adipic acid has a small net dipole moment as a whole molecule. Therefore, we can conclude that adipic acid is polar, but not very strongly.

Conclusion: How Does Polarity Affect Adipic Acid’s Properties?

The polarity of adipic acid affects its physical and chemical properties in various ways. For example, adipic acid is soluble in water and other polar solvents, but not in nonpolar solvents like hexane or benzene. This is because polar molecules can form intermolecular forces like hydrogen bonds or dipole-dipole interactions with other polar molecules, but not with nonpolar molecules. Adipic acid also has a relatively high melting point (152 °C) compared to other dicarboxylic acids with similar molecular weights, such as succinic acid (185 °C) or glutaric acid (98 °C). This is because adipic acid has more intermolecular forces due to its polarity than these other acids, which are more symmetrical and less polar. Adipic acid also reacts differently with some reagents depending on its polarity. For example, adipic acid can undergo electrophilic addition reactions with bromine or chlorine, but not with iodine. This is because bromine and chlorine are more electronegative than iodine, and can attract the electrons from the partially positive carbon atoms in adipic acid more easily.