Chapter 24 - Amines and Heterocycles Flashcards
(43 cards)
Higher the pKa, higher the _____.
basicity
Rank the following in increasing basicity:
ammonia, tertiary amine, primary amine, secondary amine, arylamine
arylamine < ammonia < 1º < 3º < 2º
more resonance = more acidic
Amides (RCONH2) are _____ _____, in contrast with amines.
not basic
Primary and secondary amines can act as very _____ _____.
weak acids
The proton from N–H can be removed by a sufficiently strong ( acid / base ).
base
Any electron withdrawing group in the ortho or para position of an arylamine will _____ the basicity.
decreases
(–CN & –NO2 are strongest)
(–Cl & –Br work well, too)
Any electron donating group in the ortho or para position of an arylamine will _____ the basicity.
increases
–NH2, –OCH3, –CH3
Primary amines can be prepared with the reduction of nitriles (–CN) and amides (–CONH2) with _____.
LiAlH$
Arylamines can be prepared from _____ of an aromatic compound and _____ of the nitro group.
nitration; reduction (= gain of H)
Reduction by catalytic hydrogenation over platinum is suitable if…
no other groups can be reduced.
C=O ==> CH2OH
Ammonia and other amines are good _____.
nucleophiles
Azide ion (N3-) displaces a _____ ion from a primary or _____ alkyl halide to give an alkyl azide (RN=N+=N-)
halide; secondary
1º or 2º alkyl halide gains azide ion from _____. It is reduced with _____ to form the amine.
NaN3; LiAlH4
Gabriel amine synthesis looks like a(n) _____ when trying to form a(n) _____ _____.
angel; primary amine
Reductive amination uses a 1º, 2º, or 3º amine and _____ to turn the _____ into an amine.
NaBH4; carbonyl
Carboxylic acid derivatives can be converted into _____ _____ with loss of one carbon atom by both Hofmann rearrangement and Curtius rearrangement.
primary amines
Hofmann rearrangement involves a(n) _____ _____.
primary amide
Curtius rearrangment involves a(n) _____ _____.
acyl azide
Hofmann rearrangement is when a primary amide (RCONH2) is treated with _____ and _____.
Br2 (or Cl2); base
Curtius rearrangement is when a(n) –R group from the C=O carbon atom migrates to the neighboring _____.
nitrogen
Curtius rearrangement reaction occurs when an acyl azide…
is heated.
Primary and secondary amines can be acylated by _____ _____ _____
nucleophilic acyl substitution
Hofmann elimination converts an amine into…
an alcohol
Hofmann elimination requires a better leaving group, so –NH2 must be converted to…
a quaternary ammonium salt (+N(CH3)3 I-)
