Phenol and Sodium Hydroxide Reaction | C6H5OH + NaOH
Phenol (C6H5OH) has an enough acidity to react with aqueous sodium hydroxide (NaOH). As products, sodium phenoxide (salt) and water are given. This reaction is a weak acid - strong base reaction and also important in explaining acidic behavior of organic compounds.
Phenol reacts with aqueous NaOH to produce sodium phenoxide and water
- Phenol is a weak acid and aqueous sodium hydroxide is a strong base. So, this reaction is a weak acid - strong base reaction.
- Formed product, sodium phenoxide is a moderately strong base.
C6H5OH + NaOH → C6H5O-Na+ + H2O
Because aliphatic alcohols do not react with aqueous NaOH, we can identify phenol from aliphatic alcohols such as ethanol. But, you cannot separate carboxylic acids (such as acetic acid) from phenol because carboxylic acid reacts with aqueous NaOH solution.
pH change of the reaction
Solubility of phenol in water is poor. However phenol solution is acidic. When sodium hydroxide is added slowly, pH value increases. When all phenol amount is finished, formed sodium phenoate is remaining in the solution and solution become basic because sodium phenoate is basic . Then, you add one more several drop of NaOH, solution become more basic and pH value will be more increased.
Heat of reaction
This reaction is an exothermic one. Also reaction of phenol and NaOH is a neutralization enthalpy. But standard enthalpy of neutralization is lower than strong acid - strong base reaction because phenol absorb energy to break its O-H bond.
How other phenol derivatives react with aqueous NaOH?
When other, different groups are attached to the benzene ring, acidic characteristics of phenol is changed.
- If, deactivators like nitro groups (-NO2) are attached, acidity of the phenolic group increases. Deactivators attract electrons. Therefore, electrons density of -OH group decreasing resulting increasing δ+ charge on hydrogen atom. When δ+ charge of hydrogen increases, acidic property of phenol increases.
Why phenol and NaOH reaction is important in organic chemistry?
Reeaction of phenol and aqueous NaOH can be used to identify alcohols from phenol. Alcohols do not react with aqueous NaOH. You can see, when aqueous NaOH is added to phenol, temperature of the reactant mixture increases and an aqueous solution is formed.
What is this formed aqueous solution?
Phenol is not a soluble organic in water and exists as a separate layer. But, when phenol reacts with aqueous NaOH, product sodium phenoate is soluble in water.
Though phenol can be identified from alcohols from the reaction with aqueous NaOH, you cannot idenstify phenol from carboxylic acids because, carboxylic acids react with aqueous NaOH.
Ph-OH + NaOH → Ph-O-Na+ + H2O
Ph- denotes phenyl group.
Questions asked by students
Ask your question and find the answer free.
Is it a similar reaction to sodium and phenol reaction?
No. Both reactions will give same salt (sodium phenoxide). But, with sodium, hydrogen gas is released. With sodium hydroxide, water is given. Phenol and sodium reaction is a acid - metal reaction.
What are the uses of phenol + naoh reaction?
Product, sodium phenoxide given by the phenol and sodium hydroxide has many uses in chemistry.
- As a preservative
- cosmetic biocide in cosmetics and personal care products
- cleanse the skin or to prevent odor by destroying or inhibiting the growth of microorganisms