Chapter 1 and 2

Alkane

Add: -ane

Alkene

Add: -ene

Alkyne

Add: -yne

Alcohol

ROH

Add: -ol

RCl

RSR

Ether

ROR

Epoxide

RNH2

Haloalkane

Aldehyde

Ketone

Carboxylic Acid

Acid Anhydride

Ester

Amide

Acyl Halide

Amine

RNH2

Nitrile

RC(triple bond)N

RNO2

Thiol

RSH

Named by identifying the longest straight carbon chain containing the -OH group.

The -ane suffix is replaced with -anol

The location of the -OH group on the chain is designed by a number

Alcohol Takes Priority

Halogens has same priority as methyl groups

2,2-Dimethyl-1-propanol

2-chloro-2-methylpentane

Primary - The C connected to the alcohol is connected to 1 other carbon

Secondary - The C connected to the alcohol is connected to 2 other carbons

Tertiary - The C connected to the alcohol is connected to 3 other carbons

Stronger van der Waals forces

• Dipole-dipole

• Dipole / induced-dipole

• Induced-dipole / induced-dipole

Amounts of carbons in the main chain (more carbons higher boiling point)

Branching (increased branching decreased boiling point)

Small alcohols are soluble in water

(Methyl and ethyl are considered small)

Tertiary most reactive

If two states are similar in energy, they are similar in structure

1. Alcohol protonation (OH bonds with H)

2. Carbocation formation (H2O leaves)

3. Anion reaction with carbocation

A molecule in which a carbon atom has a positive charge and three bonds

sp2 hybridized (molecular geometry is trigonal planar)

pz orbital is empty and perpendicular to the bond

tertiary

In carbocations: alkyl groups provide MORE inductive donation than hydrogens

‘Sigma bond to p orbital donation’

3 centers sharing 2 electrons

• inductive donation by alkyl groups along the sigma bond

• hyperconjugation, a through space donation of electron density by bonds that are adjacent and parallel to the empty p orbital

Tertiary (it forms most stable carbocation)

Not stereospecific

(But an SN1 reaction gives products that partially invert. Leading to a mixture

of S and R products generally)

Hydride Shift

Methanide Shift (Alkyl Shift)

In an SN1 reaction after carbocation formation:

A hydrogen atom from a higher order carbon atom will shift to the charged carbon

Therefore the anion will bond to the higher order carbons

Makes it more stable

In an SN1 reaction after carbocation formation:

A carbon atom from a higher order carbon atom neighbors to charged carbon will shift to the charged carbon

Therefore the anion will bond to the higher order carbon, that is now charges

Makes it more stable

(only happens if the donating carbon is connect to 2 more carbons than the charged carbon)

In real life the SN1 reaction for forming alkyl halides is _Not Always_ convenient

In SN1 Substitution Nucleophilic UNIMOLECULAR

In SN2 Substitution Nucleophilic BIMOLECULAR

SN2 reactions are for sp3 carbons only

Does not work on alkenyl or aryl halides

An atom or ion with lone pairs used to form bonds

• Lewis base

• Typically anionic (more negative is stronger)

• Charge balanced by metal cations (usually is a salt)

All HALIDE ANIONS are nucleophiles

A group that is lost during a nucleophilic substitution or elimination

Often halogens

Size (the larger the halide the better the leaving group)

Weak Base (the weaker the base the better the leaving group)

The WEAKER the base the better the leaving group

an atom or a molecule that seeks an molecule containing an electron pair available for bonding

The concentration of the electrophile and the nucleophile

No

SN2 reactions are concerted

A nucleophile makes a bond with the electrophilic carbon

Leaving group is pushed out

Reversal of 3-D arrangement

Stereospecific

Inversion of configuration

Nucleophile attacks from the opposite side of leaving group

Back-side attack

Primary

Small

Measure of a Lewis base’s (nucleophile) ability to perform a substitution

Charge (anion is more reactive than neutral analogue)

Acidity (if the same atom the more basic more nucleophilic)

Steric bulk (if the same anion the less steric bulk the more reactive)

Electronegativity (less electronegative the more nucleophilic)

Gets less reactive as you move to the right

Gets more reactive as you move down

Both SN1 and SN2 benefit from polar solvents

SN2 reacts fastest with APROTIC solvents

Protic solvents solvate nucleophiles too effectively

SN1 reacts fastest with PROTIC solvents

Polar protic solvents like water, alcohol or hydrogen halides lower the transition state energy of SN1 reactions

A hydrogen bond donor

They are very weak bases so good leaving groups and poor nucleophiles

a logical approach to finding a synthetic pathway and can be a first step in planning a synthesis

• Replacing the -ane ending of the corresponding alkane with -ene

• The alkene corresponding to the longest continuous chain that includes the double bond is the parent chain

• Number in the direction that gives the doubly bonded carbons lower numbers (alcohols still have priority)

The 2 groups ranked higher using the Cahn-Ingold-Prelog rules, are on the same side of the double bond (both up or both down)

Zame

The 2 groups ranked higher using the Cahn-Ingold-Prelog rules, are on the opposite sides of the double bond (one up or one down)

Epposite

Number of substituents (the more substituents the more stable because Hyperconjugation)

Orientation (trans molecules are more stable than cis, E is more stable than Z)

Bulky group are more stable

Exception: in small and medium rings (less than 12 carbons) cis alkenes are more stable than trans

the functional groups attached directly onto the alkene pi bond

since double bonds lack rotation, the polarity can be additive or cancel out depending on position

The most branched alkene will form

Regioselectivity of alcohol dehydration

A preference that the majority of the product molecules exhibit

The product that is easier to make will be made more often

1. Alcohol protonation (OH bonds with H)

2. Carbocation formation (H2O leaves)

3. A base takes a proton (H) from the carbocation

4. The 2 electrons from the proton from a double bond, forming the alkene

1. Hydrogen removed by strong base, electrons used to form a double bond

2. Leaving group is pushed out

Regioselective

Stereoselective

Doubling the concentration of either reagent doubles the rate

• Go through SN1/ E1 in the absence of anionic nucleophiles

• Go through E2 with strong bases like alkoxide or hydroxide

Molecules that can be superimposed on its mirror image