Amine basicity, nomenclature, and characteristic reactions of nitrogen-containing organic compounds tested on the MCAT.
34 cards · basic cards · AI-written, checked twice. Edit anything.
- What is a primary (1 degree) amine?
- An amine with nitrogen bonded to one carbon group and two hydrogens.
- What is a secondary (2 degree) amine?
- An amine with nitrogen bonded to two carbon groups and one hydrogen.
- What is a tertiary (3 degree) amine?
- An amine with nitrogen bonded to three carbon groups and no hydrogens.
- What is a quaternary ammonium salt?
- A nitrogen bonded to four carbon groups, carrying a permanent positive charge.
- Why are amines basic?
- The nitrogen has a lone pair of electrons that can accept a proton.
- What is the approximate pKa of a protonated aliphatic amine (R-NH3+)?
- Around 10 to 11.
- How does alkyl substitution on nitrogen affect amine basicity in the gas phase?
- It increases basicity, because alkyl groups donate electron density inductively and stabilize the positive charge on the protonated amine.
- In aqueous solution, why do tertiary amines often not follow the gas-phase basicity trend?
- Steric hindrance and poor solvation of the bulky protonated ammonium ion reduce their basicity.
- Is aniline more or less basic than cyclohexylamine?
- Less basic.
- Why is aniline less basic than an aliphatic amine?
- The nitrogen lone pair delocalizes into the aromatic ring, making it less available to accept a proton.
- How does an electron-withdrawing group like nitro on an aniline ring affect its basicity?
- It decreases basicity by pulling electron density away from the nitrogen lone pair.
- How does an electron-donating group like methoxy on an aniline ring affect its basicity?
- It increases basicity by pushing electron density toward the nitrogen.
- Are amides basic like amines?
- No, amides are only very weakly basic.
- Why is the nitrogen lone pair in an amide much less available than in an amine?
- It is delocalized by resonance into the carbonyl group.
- Why is pyridine basic?
- Its nitrogen lone pair sits in an sp2 orbital in the plane of the ring, not part of the aromatic pi system, so it is free to accept a proton.