Citric Acid vs Ascorbic Acid
Citric acid and ascorbic acid are organic compounds, which can act as acids. Organic acids essentially contain hydrogen and carbon with another element. Other most common organic acids are acetic acid, lactic acid, formic acid, etc. These acids have a –COOH group. Therefore, they can act as proton donors. Both citric acid and ascorbic acid are found in citrus fruits, so there can be confusion between the two. However, they are entirely different two molecules.
Citric acid is an organic acid which is present in citrus fruits. For example, lime, lemon, oranges can be considered as citrus fruits. A common feature to all of these fruits is their bitter taste, and citric acid is accountable for this. According to the amount present, the bitterness varies from fruit to fruit. Citric acid is present in some vegetables too. This is a weak acid relative to the inorganic acids like HCl or sulphuric acid, with the chemical formula C6H8O7. It appears as a white crystalline solid, and upon solvation in liquid, it acts as proton donor. It is also soluble in water. Citric acid has three –COOH groups, therefore, shows the properties of other carboxylic acids. For instance, when heating, it decomposes by giving carbon dioxide and water. When compared with other carboxylic acids, citric acid is stronger because the anion can be stabilized by intra molecular hydrogen bonding.
Among the many usages, we use citric acid daily as a food additive. It adds flavor to the drinks. Citric acid is a good natural cleanser. Thus, it is used in cleaning products and beauty products. Another, reason for using citric acid in skin product is its ability to act as an antioxidant. Further, citric acid is a good chelating agent. It can bind with metals and minerals, so it helps the body to absorb and digest them more easily. Citric acid is an intermediate in the citric acid cycle; hence, it is a molecule present in all the living things.
Ascorbic acid is also a naturally occurring organic acid. L-ascorbic acid is also known as vitamin C, and this is an essential nutrient for humans. It has the molecular formula of C6H8O6. This is a white color solid, but sometimes may appear in a slight yellow color too. Ascorbic acid has the following cyclic structure with acidic groups.
Ascorbic acid is soluble in water and other polar organic solvents. When a loose proton from a hydroxyl group bonded to vinyl carbon, the molecule is stabilized by resonance stabilization. This stability of deprotonated conjugate base of ascorbic acid, makes it more acidic than the other hydroxyl groups. Ascorbic acid is an antioxidant like citric acid.
What is the difference between Citric and Ascorbic acids?
• Ascorbic acid has a cyclic structure, but citric acid has a linear structure.
• Ascorbic acid is the acting compound in what we are taking as vitamin C. Citric acid is used in vitamin C tablets just for giving the taste; it does not have much of a nutrient value.
• Citric acid has three carboxyl groups, and they can donate protons when acting as acids, but in ascorbic acid, there is not any –COOH groups (if the ring opens there can be a –COOH). The proton donation is from the hydroxyl groups in the molecule.
• In citric acid, the deprotaonated ion is stabilized by intra molecular hydrogen bonding. In ascorbic acid, the deprotonated molecule is stabilized by resonance.