Tetramethylammonium hydroxide (TMAH) is a strong base because it undergoes complete ionization in water, producing hydroxide ions (OH-) which are responsible for its basic properties. The strength of a base is determined by its ability to accept protons (H+) or donate electron pairs to form new chemical bonds.
There are a few factors that contribute to Tetramethylammonium hydroxide being a strong base:
1. Presence of a hydroxide ion: Tetramethylammonium hydroxide contains the hydroxide (OH-) ion, which is a strong base on its own. When TMAH is dissolved in water, it readily dissociates into tetramethylammonium cations (TMA+) and hydroxide anions, providing a high concentration of hydroxide ions in the solution.
2. Stability of the conjugate acid: The conjugate acid formed when Tetramethylammonium hydroxide donates a proton is a relatively weak acid, which enhances the strength of Tetramethylammonium hydroxide as a base. The resulting tetramethylammonium cation (TMA+) is stabilized through resonance and electron delocalization, making it a weakly acidic species.
3. Steric effects: The bulky structure of the tetramethylammonium cation (TMA+) hinders the interaction of the positively charged nitrogen atom with the lone pairs of electrons on the hydroxide ion. This steric hindrance reduces the tendency of TMA+ to bind to the hydroxide ion, allowing for easier detachment of the OH- ion and increasing the basicity of TMAH.
Overall, the combination of high hydroxide ion concentration, stability of the conjugate acid, and steric hindrance contribute to Tetramethylammonium hydroxide being a strong base.
