Chapter Alcohols and Phenols. Chapter 1: Covalent Bonding and Structure. Chapter 2: Thermodynamics and Chemical Kinetics. Chapter 3: Alkanes and Cycloalkanes. Chapter 4: Stereoisomerism. Chapter 5: Acids and Bases. Chapter 7: Alkene Structure and Reactivity. Chapter 8: Reactions of Alkenes. Chapter 9: Alkynes. Chapter Ethers, Epoxides, Sulfides. Full Table of Contents. This is a sample clip. Sign in or start your free trial. Previous Video Next Video. Next Video Embed Share.
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Save to playlist. Filter by:. As a result the phenoxide ion has less tendency than an alkoxide ion to combine with a proton. If groups that stabilize negative charge are attached to the benzene ring, the charge may be further delocalized, and the phenol becomes even more acidic. Groups that are meta directing in aromatic substitution because they repel an adjacent positive charge will increase the acidity of phenol because they stabilize an adjacent negative charge.
Attachment of a nitro group to phenol increases its acidity. In this reaction, the hydrogen ion has been removed by the strongly basic hydroxide ion in the sodium hydroxide solution. Phenol isn't acidic enough to react with either of these. Or, looked at another way, the carbonate and hydrogencarbonate ions aren't strong enough bases to take a hydrogen ion from the phenol. Unlike the majority of acids, phenol does not give carbon dioxide when you mix it with one of these.
This lack of reaction is actually useful. You can recognise phenol because:. Acids react with the more reactive metals to give hydrogen gas. Phenol is no exception - the only difference is the slow reaction because phenol is such a weak acid. Phenol is warmed in a dry tube until it is molten, and a small piece of sodium added.
There is some fizzing as hydrogen gas is given off. The mixture left in the tube will contain sodium phenoxide. Jim Clark Chemguide. Why is phenol acidic?
For example, in solution in water: Phenol is a very weak acid and the position of equilibrium lies well to the left. Properties of phenol as an acid With indicators The pH of a typical dilute solution of phenol in water is likely to be around 5 - 6 depending on its concentration.
With sodium carbonate or sodium hydrogencarbonate Phenol isn't acidic enough to react with either of these. You can recognise phenol because: It is fairly insoluble in water. It reacts with sodium hydroxide solution to give a colourless solution and therefore must be acidic.
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