Amines

• What are the structures of primary, secondary, and tertiary amines, and a quaternary ammonium ion?

  Primary amine: RNH2, Secondary amine: R2NH, Tertiary amine: R3N, Quaternary ammonium ion: R4N+

  
• How do you name amines?

  Amines are named using the suffix -amine or the prefix amino-
• Why are amines so reactive?

  Amines are reactive due to the lone pair of electrons on the nitrogen and the polar N-H bond
• What is the shape of amines around the nitrogen atom and what is the bond angle?

  The shape of amines around nitrogen is trigonal pyramidal with a bond angle of 107°
• What kind of intermolecular forces do amines have and why?

  Amines have hydrogen bonding due to the polar N-H bond and the lone pair of electrons on the nitrogen atom
• Do amines have intermolecular forces that are stronger or weaker than alcohols, and why?

  Amines have weaker intermolecular forces than alcohols because nitrogen has a lower electronegativity than oxygen, leading to weaker hydrogen bonding
• How can amines act as bases?

  Amines can act as bases by accepting a proton due to the lone pair on the nitrogen atom

  
• When do amines act as nucleophiles?

  Amines act as nucleophiles when they bond with an electron-deficient carbon atom by donating the lone pair from nitrogen
• What is the product from the basic action of an amine with water?

  The product is an ammonium ion (RNH3+) which forms a salt with an anion

  
• Write an equation for methylamine reacting with HCl.

  CH3NH2 + HCl → CH3NH3+Cl-
• In order to be the strongest base, what must a particular amine have?

  The amine must have the greatest electron density around the nitrogen atom, making it a better electron pair donor
• What effect do alkyl groups have on electron density and base strength in amines?

  Alkyl groups have a positive inductive effect, increasing electron density around nitrogen and making it a stronger base

  
• Place the following in order of base strength: NH3, 1° amine, 2° amine, phenylamine.

  2° amine > 1° amine > NH3 > phenylamine
• How can primary amines then form 2° and 3° amines and 4° ammonium ions?

  Primary amines can form 2° and 3° amines and 4° ammonium ions through multiple substitutions as nucleophiles attacking the original haloalkane
• What are the problems with the method of forming amines through multiple substitutions?

  The method is not efficient as it yields a low amount of 1° amine due to multiple substitutions
• How would you maximize the yield of the primary amine?

  To maximize the yield of the primary amine, use excess ammonia
• What type of mechanism is the reaction of a haloalkane with a cyanide ion?

  The mechanism is nucleophilic substitution
• What conditions are required for the reaction of a haloalkane with a cyanide ion, and what is the product formed?

  The reaction requires ethanol as a solvent and produces a nitrile
• How do you get from a nitrile to a primary amine, including the name of the reaction type and reagents/catalysts?

  Reduction using a Nickel/Hydrogen catalyst
• Why is the reduction of nitriles to primary amines a purer method of synthesizing amines?

  This method is purer because only the primary amine can be formed
• What conditions are needed to form nitrobenzene from benzene?

  Concentrated H2SO4 and HNO3 are needed to form the NO2+ ion for electrophilic attack
• How do you form an ammonium chloride salt from nitrobenzene, and what conditions are needed?

  Reduce the nitrile using Tin/HCl at room temperature to form an ammonium salt with Cl- ions
• Write the equation for the reaction of nitrobenzene to phenylamine.

  C6H5NO2 + 6[H] → C6H5NH2 + 2H2O
• What mechanism is used for forming amides from acyl chlorides and amines?

  The mechanism is nucleophilic addition/elimination

  
• Draw a mechanism for the reaction of ethanoyl chloride with ethanamine.

  Mechanism involves nucleophilic attack by ethanamine on the carbonyl carbon of ethanoyl chloride
• Why are amines so reactive?

  Amines are reactive due to the presence of a lone pair of electrons on nitrogen and the polar N-H bond
• Draw the structures of primary, secondary, and tertiary amines and a quaternary ammonium ion.

  Primary amine: RNH2, Secondary amine: R2NH, Tertiary amine: R3N, Quaternary ammonium ion: R4N+