acidity and basicity pt2

Lewis Acids and Bases

concept is based on the fact that acid–base reactions involve the transfer of electron

pairs from one substance to another

acid

is a substance accepts an electron pair; electron pair acceptor.

base

is a substance that donates an electron pair; electron pair donor.

covalent bond

The donated electron pair is shared between the acid and the base in a _.

Lewis acids

much broader definition of

acid

Lewis acids

not limited to those with

hydrogen

Lewis acids

substances that have unfilled

valence orbitals

H2O, HCl, HBr, HNO3, H2SO4 (neutral proton donors)

Carboxylic acid, Phenol, Alcohol

Li+, Mg2+ (cations)

AlCl3, TiCl4, FeCl3, ZnCl2 (metal compounds)

Some Lewis acids

Lewis bases

substances with a pair of

nonbonding electrons

alcohol, ether, aldehyde, ketone, acid chloride, carboxylic acid, ester, amide, amine, sulfide, organotriphosphate ion

Some Lewis bases

Curved arrows

show where

the electrons start from and

where they end up!

not from lewis acid to the lewis base

in any rxn we show the flow of electrons, and you start from lewis base and point it to the destination lewis acid. when u donate electrons from lb to la there will be a covalent bond

flow of electrons, not protons

curved arrows show the

Lewis Acids

also called electrophiles

Lewis Acids

also called electrophiles because they are attracted to electrons (electron

pair acceptor)

Lewis Bases

also called nucleophiles

Lewis Bases

also called nucleophiles because they are attracted to protons (electron

pair donor)

arrhenius acid

produce hydrogen or hydrroneum ions in aq solns

arrhenius bases

produce hydroide ions in aq solns

bronsted lowry acids

proton donors

bronsted lowry bases

proton acceptor

lewis acids

electron pair acceptors

lewis bases

electron pair donors

Organic Acids

Organic compounds that contain a hydrogen atom bonded to an electronegative oxygen

atom (O-H)

Organic Acids

Organic compounds that contain a hydrogen atom bonded to a carbon atom next to a

C=O bond (O=C-C-H)

15.54

methanol pKa

4.76

acetic acid pKa

19.3

acetone pKa

alcohol, phenol, carboxylic acids, acetic acid

or, (aromatic alcohols) can behave as acids because they contain hydrogen bonded to an electronegative oxygen

Organic Bases

org compounds that act as bases including Nitrogen-containing compounds

Organic Bases

Oxygen-containing compounds (if reacting with a sufficiently strong acid)

methylamine, methanol, acetone

org bases ex

carboxylic acid

most common ex org acid

amines

most common ex org base

methylamine

- may lone pair on nitrogen

methanol

- can act as acids, but since may lone pair sa oxygen if reacted sa strong acid

acetone

- lone pairs on oxygen