CEM 252 - Alcohols

What is the rule when numbering the longest carbon chain with an alcohol group?

Always give the OH the lowest possible number

When do we use trans/cis or E/Z?

-Use trans/cis when there are H's on either side of a double bond

-Use E/Z when the there are different priority substituents on a double bond (ex. Br and H)

When do we include stereochemistry when naming compounds?

When there is a chiral center (often a wedge/dash)

What name do we use when there is two OH groups on a compound?

Diol

What is a phenol?

A double bonded ring with and OH group coming off of it

If there is more than one OH group on a double bonded ring, what is it called?

Benzene

What are the names of the following different types of substitutions on aromatics?:

1. 1, 2

2. 1, 3

3. 1, 4

1. ortho (o-)

2. meta (m-)

3. para (p-)

Hydrogen bonding ___________ solubility.

increases

Solubility ______________ with the increasing length of the carbon chain.

decreases

Acid =

molecule that likes to donate protons (H+)

Is alcohol a strong or a weak acid?

Weak

What are the pKa's of the following acids?:

1. H-Cl

2. Carboxyl

3. Water + alcohol

4. Ammonia + amine

5. Alkane

1. -7

2. 5

3. ~16

4. ~30-35

5. 60

The lower the pKa value, the _______ acidic an acid is.

more

What are the 4 parameters that increase acidity?

1. Electronegativity

2. Size

3. Resonance

4. Induction

What are the traits of a group that is ED through resonance?

Atoms with lone pairs can share their electrons through bonds (resonance)

What are the traits of a group that is EW through resonance?

Atoms in pi-bonds (usually heteroatoms) can accept electrons through bonds

What are the traits of a group that is ED through induction?

-R groups

-Make area around them more electron rich

What are the traits of a group that is EW through induction?

-Halogen groups (F, Cl, Br, I)

-Electronegative, attract electrons

Electron donating groups _____________ acidity.

decrease

What are the common bases for an acid base reaction?

Na+ and NH2- or Na+ and H-

Nucleophile =

molecule with lone pair

What are the traits of an SN2 reaction?

-1-step

-Happens with methyl, 1°, 2°

-Nucleophile attacks the carbon and kicks out/replaces LG

-Stereochemistry changes (opposite)

What are the traits of an SN1 reaction?

-2-step (carbocation intermediate)

-Happens with 2° and 3°

-Rearrangement can occur to form a more stable cation

-Stereochemistry does not matter (can be wedge or dash)

How do we decide between SN1 or SN2 for 2° halides?

-Look at the nucleophile

-If the nucleophile is neutral, then SN1

-If the nucleophile is negative, then SN2

What are the products of an addition of H-OH when the reactants are H+(cat) and H-OH?

-An H and OH

-The OH goes on the more substituted carbon

-Carbocation intermediate (possibility for rearrangement)

-Stereochemistry does not matter

What are the products of an addition of H-OH when the reactants are HgSO4, H2C and NaBH4?

-An H and OH

-The OH goes on the more substituted carbon

-No rearrangement

-Can show both stereochemistry or just lines

What are the products of an addition reaction when the reactant is H3O+?

-An H and OH

-OH goes on the more substituted carbon

-Rearrangement can occur from carbocation

What are the products of an addition reaction when the reactants are BH3 and H2O2?

-An H and OH

-The OH goes on the LEAST substituted carbon

-Stereochemistry needs to be the same for OH and H

What are the products of a dihydroxylation reaction when the reactants are OsO4 and NaHSO3?

-2 OH's

-The stereochemistry of the OH's needs to be the same

What is an aldehyde?

R-O=C-H

What is a ketone?

R-C=O-R

What are the products of a reduction reaction when the reactants are NaBH4 or LiAlH4 and H+?

-The C=O is replaced with an H and OH

How can we make OH a better leaving group?

Add acid (H+) to make OH2+

What are the products of an acidic dehydration reaction when the reactants are H+ (H2SO4) and heat?

-A double bond will form on either side of the LG

-The major product will be formed on the more substituted carbon

-Rearrangement can occur with E1 reactions

What are the products of a POCl3 dehydration reaction when the reactants are POCl3 and pyridine?

-A double bond will form on the more substituted side of the LG

-POCl3 does NOT have rearrangement

True or false: OH cannot be used as a leaving group in a substitution reaction unless it is reacting with an acid.

True

What is the best acid and the worst acid out of the following?:

HBr, HCl, HI

HI > HBr > HCl

What are the products of an SN2 SOCl2 reaction?

-The LG will be replaced by a Cl

-The stereochemistry will be the opposite

What are the products of an SN2 PBr3 reaction?

-The LG will be replaced by a Br

-The stereochemistry will be the opposite

What are the traits of a tosylation reaction?

-OH can be a LG group with Ts-Cl because it removes the H

-Stereochemistry stays the same

-A Ts-Cl bonds to the oxygen

-Can have substitution reactions where a OTs product is formed and stereochemistry changes

What are the definitions of the following?:

1. Oxidation =

2. Reduction =

1. Losing hydrogen

2. Addition of hydrogen

Oxidation depends on the type of ______________.

alcohol (ex. 1°, 2°, or 3°)

What reactants may be used in a strong oxidation reaction?

CrO3, H3O+ or KMnO4 or K2Cr2O7 or Na2CrO4

What reactants may be used in a mild oxidation reaction?

PCC

What type of products can a 1° alcohol form in an oxidation reaction?

-An aldehyde if it is a weak oxidant (ex. PCC)

-Carboxylic acid if it is a strong oxidant (ex. CrO3)

What type of products can a 2° alcohol form in an oxidation reaction?

A ketone (regardless of a strong or mild oxidant)

What type of products can a 3° alcohol form in an oxidation reaction?

No oxidation because there is no H