organic chem 9,10 Flashcards
what would a strong acids pKa be?
above 12
what is the difference between bronsted Lowry acid and lewis acid?
bronsted Lowry acid is a compound that donates a hydrogen ion (H+), BUT A LEWIS ACID accepts pair of electrons
what’s a strong base examples?
carbocation c-
weak bases example?
F- Cl- Br- I-
common example of lewis acid but not bronsted Lowry acid?
BF3
AlCl3
what is a lewis acid base reaction?
any reaction in which species donates an electron pair to another species is a lewis base reaction
-Lewis base donates an electron pair to a lewis acid
what is a Lewis acid also called?
ELECTROPHILE
(both electron acceptors)
what is a lewis acid?
e- acceptor
what is a lewis base and what else can it be known by?
lewis base is electron donor
known as nucleophile
what does a low pKa mean and what does a high one mean?
low pKa is strong acid and high pKa is strong base
what is the structure and shape of amines
nitrogen has 5 valence electrons
3 covalent bonds
one lone pair
trigonal pyramidal
amines are categories how?
primary
secondary
tertiary
depending on R groups attached
R groups can be alkyl or aryl (aromatic compound)
how can amines be chiral?
if its attached to 3 DIFFERENT GROUPS that are not hydrogen PLUS THE LONE PAIR MAKE IT 4
what is pyramidal inversion?
when the amine inverts like and umbrella but the intermediate is a planar.
how do amines form quaternary ammonium salts ?
4 groups attached to N+ but these cannot undergo pyramidal inversion
are the enantiomers separable of ammonium salts?
yes
which amines have higher bp?
primary and secondary as they have one or two hydrogens bonded to them so more H bonds but tertiary has no hydrogen so no hydrogen bonds
what is the trend for solubility of amines?
amines are soluble in water and solubility decreases with number of carbons.
what are the properties of alkyl amines?
moderately volatile (boils fast, evaporate)
liquid (lower bp than alcohols)
doesn’t smell nice
are amines weak or strong bases?
amines are generally weak BASES (bronsted Lowry)
ELECTRON PAIR DONOR
n lone pair accepts proton
what is the basic constant?
Kb = [h+][oh-] / [a-]
base strength in water?
primary AND SECONDARY
STRONGER BASES IN WATER
ARE AROMATIC AMINES STRONGER BASES?
AROMATIC AMINES MUCH WEAKER BASES THAN ALKYL AMINES
electron withdrawing groups decrease increase basicity?
decrease basicity(as they )
electron donating groups increase or decrease basicity
increase
basicity vs amine
more alky group = more basic amine =lower pKb
amides c=o (-nh2) vs basicity
amides are not basic the N lone pair is not available to act as base
