Ethers, Ketones, aldehydes

Physical properties of ethers

They have no H’s on the oxygen, so theres no hydrogen bonding

They also have low melting and boiling points

Ether as a solvent

They can dissolve polar, non polar and hydrogen bonding compounds

What wont ether react with

bases, reducing agents, nucleophiles and dilute acids

What will ether react with

strong and hot acids, oxidizing agents

What is the industrial (first) preparation of ethers

reacting a primary alcohol with an acid (ex: h2so4). need to signify that you have 2 of the starting material

Why can only primary alcohols be used in the industrial (first) style of making ethers

Because it is an sn2 mechanism. using secondary or tertiary alcohols will lead to dehydration

What is the industrial (first) style of preparing ethers useful for

it’s useful for making symmetrical ethers, otherwise it results in mixtures

What is the name of the second style of preparation for ethers

Williamson ether synthesis

What is the williamson ether synthesis

its when an alcohol reacts with a strong base in the presence of an alkyl halide or alkyl tosylate

What is the mechanism for the williamson ether synthesis

the base deprotonates the alcohol and makes an alkoxide ion. then it reacts with the alkyl halide to add an alkyl group onto the alkoxide ion

What are the limitations of the alkyl halide in the williamson ether synthesis?

it needs to be a primary alkyl halide or else it will be eliminated

What is the third way to prepare eithers

Alkoxymercuration/demurcuration

What is Alkoxymercuration/demurcuration in terms of making an ether

it’s when an alkene reacts with Hg(OAc)2,ROH followed by NaBH4 to create an OCH3 group

What is the mechanism for an Alkoxymercuration/demurcuration to prepare an ether?

A OCH3 group is placed onto the molecule

Acidic cleavage of ethers

ethers can be cleaved by treated them with hot strong acid

Mechanism for acidic cleavage of ethers

the ether reacts with a strong hot acid. it cleaves at either end of the oxygen.

one side gains the halide (halide attacks the less substituted carbon) and the other side gains an OH.

after a while, excess acid attacks again, turning the OH into water, and then the halide takes its place

How do you prepare epoxides industrially

by using O2,heat/Ag2O

Why is making epoxides industrially not common

they’re expensive and may oxidize other groups

Mechanism for making epoxides industrially

What is the halohydrin formation for making epoxides

you treat a halohydrin with a base to induce an sn2 reaction

what is the mechanism for the halohydrin formation of an epoxide

an alkene is treated with a halogen/water

this places an OH and a halogen on the alkene respectively

treat it with a base like OH and it turns into an epoxide

What is peroxyacid epoxidation

its when you turn an alkene directly into an epoxide

what is the mechanism for peroxyacid epoxidation

What are the reagents for peroxyacid epoxidation

MCPBA/CH2Cl2

What is the grignard way of opening an epoxide ring

you use R-MgBr/Et2O (attacks the less hindered side)

the O of the epoxide becomes an OH

the R group attached to the mgbr gets added

reacts with h3o+ to form an OH

What is the reaction of epoxides with NaOEt/EtOH

EtO- attacks the epoxide and opens it (attacks less hindered side)

the O of the epoxide goes one way while theres an ethyl group formed with an ether

What is the acidic ring opening for the reaction of epoxides

its when a poor nucleophile (such as ROH/H) reacts with an epoxide

the epoxide reacts with the H+

the attack occurs at the more substituted carbon

Crown ethers

can make ionic salts soluble in non polar organic solvents

Formula for a crown ether

(# of atoms)-crown-(#r of oxygens)

rules for aldehyde nomenclature

1. pick the longest chain with the CHO group

2. the aldehyde carbon is #1

3. drop the e in the parent alkane and add al “hexanal”

what is the parent name of an aldehyde on a ring

cyclo*alkane*carbaldehyde

rules for ketone nomenclature

1. pick the longest chain with the C=O group

2. give the carbonyl the lowest number possible

3. drop the e in the parent alkane and add one along with a number (heptan-2-one)

name for aldehyde as a substituent

formyl

name for ketone as a substituent

oxo

oxidization of secondary alcohols

• can use any oxidizing agent to turn an OH into a carbonyl

Oxidization of primary alcohols

use PCC,pyr/-2H to turn a alcohol into a aldehyde or carboxylic acid

Cleavage of an alkene using O3/(CH3)2S

makes a ketone and aldehyde

cleavage of an alkene using KMNO4 hot and concentrated

makes a ketone and carboxylic acid

What is a reagent you can use to put a aldehyde on a benzene

CO,HCl/CuCl,AlCl3 aka the gattermann koch reaction

What is 1,3-dithiane

a protecting group for ketones and aldehydes

How do you deprotect a carbonyl from thioacetal

H,HgCl2/H2O

Acid catalyzed mechanism for addition of water

adds two alcohols in place of a carbonyl

needs a driving force (use excess of water)

Base catalyzed mechanism for addition of water

What are acetals

protecting group for aldehydes and ketones that have two ethers

How do you get rid of an acetal

H+,H2O

What are the reagents for forming an acetal

2 equivalence of an ethyl with an OH/H+

hemiacetal

Addition of HCN

Addition of grignards to ketones

What is the requirement for mclafferty rearrangement

need at least on hydrogen on the gamma carbon (also needs to have an aldehyde)

Cleavage between beta and gamma carbons of an aldehyde/ketone

cation is stabilized by enol, look for a double bond that is touching the oxygen

What is the wittig reaction

turns a carbonyl into an alkene

Wittig reaction mechanism

What do you get when you react a carbonyl with a primary amine

imine

What do you get when you react a carbonyl with a secondary amine

enamine

Imine formation

Enamine formation

Reducing agent LiAlH4

very reacting, can reduce a lot of things

LiAlH4,ether/H3O

Reducing agent NaBH4

less reactive, only reduces ketones and aldehydes

NaBH4/CH3OH

Reduction by using hydrogen/metal

• can use H2/RN

• turns carbonyl into an alcohol

What happens if the carbonyl is on a benzene during a Hydrogen reduction?

instead of turning into an alcohol, it will reduce completely

Clemmonson reaction

completely removes a carbonyl

Wolff Kishner reduction

reduces carbonyls into alkanes by using NH2-NH2