Carboxylic Acid vs Alcohol
Carboxylic acids and alcohols are organic molecules with polar functional groups. Both have the ability to make hydrogen bonds, which affect their physical properties like boiling points.
Carboxylic Acid
Carboxylic acids are the organic compounds having the functional group –COOH. This group is known as the carboxyl group. Carboxylic acid has a general formula as follows.
In the simplest type of carboxylic acid, R group equals to H. This carboxylic acid is known as formic acid. Further, R group can be a straight carbon chain, branched chain, aromatic group, etc. Acetic acid, hexanoic acid, and benzoic acid are some of the examples for carboxylic acids. In the IUPAC nomenclature, carboxylic acids are named by dropping the final –e of the name of the alkane corresponding to the longest chain in the acid and by adding –oic acid. Always, the carboxyl carbon is assigned number 1. Carboxylic acids are polar molecules. Because of the –OH group, they can form strong hydrogen bonds with each other and with water. As a result, carboxylic acids have high boiling points. Further, carboxylic acids with lower molecular weights easily dissolve in water. However, as the length of the carbon chain increases, the solubility decreases. Carboxylic acids have an acidity ranging from pKa 4-5. Since they are acidic, they react readily with NaOH and NaHCO3 solutions to form soluble sodium salts. Carboxylic acids like acetic acid are weak acids, and they exist in equilibrium with its conjugate base in aqueous media. However, if the carboxylic acids have electron withdrawing groups like Cl, F, they are acidic than the un-substituted acid.
Alcohol
The characteristic of the alcohol family is the presence of a –OH functional group (hydroxyl group). Normally, this –OH group is attached to a sp3 hybridized carbon. The simplest member of the family is methyl alcohol, which is also known as methanol. Alcohols can be classified into three groups as primary, secondary and tertiary. This classification is based on the degree of substitution of carbon to which the hydroxyl group is directly attached. If the carbon has only one other carbon attached to it, the carbon is said to be a primary carbon and alcohol is a primary alcohol. If the carbon with the hydroxyl group is attached to two other carbons, then that is a secondary alcohol and so on. Alcohols are named with a suffix –ol according to the IUPAC nomenclature. First, the longest continuous carbon chain to which the hydroxyl group is directly attached should be selected. Then the name of the corresponding alkane is changed by dropping the final e and adding the suffix ol.
Alcohols have a higher boiling point than the corresponding hydrocarbons or ethers. The reason for this is the presence of intermolecular interaction between alcohol molecules through hydrogen bonding. If the R group is small, alcohols are miscible with water, but as the R group is becoming larger, it tends to be hydrophobic. Alcohols are polar. The C-O bond and O-H bonds contribute to the polarity of the molecule. Polarization of the O-H bond makes the hydrogen partially positive and explains the acidity of alcohols. Alcohols are weak acids, and the acidity is close to that of water. –OH is a poor leaving group, because OH– is a strong base.
|
What is the difference between Carboxylic Acid and Alcohol? • The functional group of carboxylic acid is –COOH, and in alcohol it is –OH. • When both groups are in one molecule, priority is given to the carboxylic acid in the nomenclature. • Carboxylic acids have a higher acidity compared to corresponding alcohols. • Carboxylic group and the –OH group gives characteristic peaks in IR and NMR spectra.
|