Alcohols, Ethers, and Epoxides Flashcards by Casi Jones

-OH groups are polar or nonpolar?

polar

soluble in water - important in drugs

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primary alcohol (carbinol carbon atom):

C-OH wich 2H bonded to C
1Rgroup

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secondary alcohol (carbinol carbon atom):

C-OH
1H bonded to Cand 2R groups

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teritary alcohol (carbinol carbon atom):

C-OH with 3R groups attached to the C

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Alcohols can form hydrogen bonds. Two further important properties:

Alcohols are soluble in water
Molecules with alcohol groups can H-bond to proteins

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what are the 2 steps of Synthesis of Alcohols?

Nucleophilic substitution on an alkyl halide
Synthesis of alcohols from alkenes
Addition of acetylides to carbonyl compounds (C=O)

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Synthesis of alcohols from alkenes
3 parts and product

a. Acid-catalysed hydration

b. Oxymercuration–demercuration

c. Hydroboration–oxidation

Markovnikov product&raquo_space;> Anti-Markovnikov product

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What reagent does Markovnikov need for dehydration reaction?

Boron

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What reagant does Anti-Markovnikov need for dehydration reaction?

Mercury

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Organometallic compounds

covalent bonds between carbon atoms and metal atoms

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Nucleophilic carbon atoms > organometallic
> gets attacked by

a strong nucleophile

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Most alkyl and alkenyl groups are not ______ enough to be deprotonated by NaNH2

acidic

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Grignard and organolithium reagents:

strong nucleophiles/strong bases

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Nucleophilic reactions are additions of what group?

carbonyl (C=O) groups

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Organometallic reagents for alcohol synthesis 3 steps

1) Formation of the Grignard reagent

2) The Grignard reagent attacks a carbonyl compound to form an alkoxide salt

3) After the first reaction is complete, water/dilute acid is added to protonate the alkoxide and give the alcohol

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[primary] formaldehyde when reagent attacks the C

the lone pair of e will shift to the O and form a primary alcohol

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secondary aldehyde froms what type of alcohol

secondary

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ketone forms what type of alcohol

tertiary (3)

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Reduction of the C=O: synthesis of 1° and 2° alcohols

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Sodium borohydride (NaBH4)
are involved in what two processes

1) Borohydride transfers a hydride ion (H:-) to carbon, forming an alkoxide ion

2) The alcohol solvent protonates the alkoxide

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What is being reduced in the second step of synthesis of 1st and 2nd alcohols and what does NOT reduce?

Reduces ketones (2˚alcohols)

Reduces aldehydes (1˚ alcohols)

Does not reduce carbonyl groups: acids, esters, and other acid derivatives

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LiAlH4 v NaBH4

LiAlH4 much stronger reagent

Easily reduces ketones (2˚alcohols) and aldehydes (1˚ alcohols)

Reduces carbonyl groups (1˚ alcohols): acids, esters, and other acid derivatives

Hydride reagents add a hydride ion (H:-), reducing the C=O to an alkoxide ion

what reagent is used?

Lithium aluminium hydride (LiAlH4)

2 steps to reduction of Reduction of the C=O: synthesis of 1° and 2° alcohols using LiAlH4:

LAH transfers a hydride ion (H:-) to carbon, forming an alkoxide ion
After the first reaction is complete, water/dilute acid is added to protonate the alkoxide

Inorganic chemistry

oxidation/reduction is a loss/gain of electrons i.e. Cr6+to Cr3+

oxidation is

adding an oxidising agent (O, O2, Br2, etc.) or losing H2

reduction is

is adding a reducing agent (H2, NaBH4, H-etc.) or losing O, O2 or X2

neither an oxidation nor a reduction: addition or loss of...

H+, -OH, H2O, HX, etc.

oxidation usually converts C-H bonds to

C-O bonds

name the 3 steps of Oxidation of alcohols:

1. Oxidation of primary alcohols to carboxylic acids 2. Oxidation of primary alcohols to aldehydes 3. Oxidation of secondary alcohols to ketones

Why is it important for our bodies to detoxify alcohol?

keep it from building up in blood and poisoning the brain

ethanol - 1 alcohol is transformed to

acetaldehyde

methanol > formaldehyde >

formic acid

a weak nucleophile (alcohol) will attack the strong electrophile. what will happen to the charge on the oxygen?

the +ive charge will move from the C to the O O will start with 2 lone pairs and then end up with only one because one is taken up by H and the other by the C that had been attacked by the nucleophile

what do we add to a weak nucleophile to make a strong nucleophile?

Na this will break the bond between the O-H, H will leave the O and leave O with 3 lone pairs with a -ive charge

alcohols - strong nucleophile = lone pair from O will attack the C in the ____ ________

weak electrophile which will attach the the alcohol (weak nucleophile)

how to turn poor electrophile to a good electrophile?

add HBr as the extra H will attach to the oxygen taking up the lone pair and leaving a +ive charge Br- will be by itself BETTER LEAVING GROUP (ACTIVATE THE OH)

Convert –OH to a better tosylate leaving group step 1 and 2

Step 1: Activation to tosylate Step 2: SN2 displacement of tosylate ion (-OTs) In 2 steps, an alcohol is transformed to a different functional group through a SN2 reaction

in an SN reaction should R group be hindered or unhindered?

R must be an unhindered primary or secondary alkyl group if substitution is to predominate over elimination

in the conversion of alcohols to alkyl halides what reaction is teritary and secondary? what about primary?

SN1 SN2

how to form ethers?

bimolecular condensation reaction that joins two (or more) molecules, often with the loss of a small molecule such as water

acidic dehydration conditions two reactions compete:

A) Elimination, dehydration to give an alkene B) Substitution, condensation to give an ether

What do we call forming an ester in alcohols?

Esterification of alcohols

explain esterification of alcohols

Replacing the -OH group of a carboxylic acid with the -OR group of an alcohol

Inorganic esters

the alkoxy ( -OR) group replaces a –OH of an inorganic acid

The Williamson ether synthesis

Alkoxide ion reacts with primary alkyl halides and tosylates to form ethe

ether synthesis = if alkyl halide is hindered? what process will happen

elimination

what are ethers?

O-R'. R may be alkyl group or aryl group [aryl - functional group derived from an aromatic]

Most common methods for ethers preparation: Williamson synthesis and bimolecular condensation of alcohols

1. Peroxyacid epoxidation

Opening of epoxide: 1. Acid-Catalysed

a. In water to form glycols b. In alcohols to form an alkoxy alcohol c. Using hydrohalic acids

b. In alcohols to form an alkoxy alcohol Protonation of oxygen (forming a good leaving group), followed by the alcohol attack as if it were an ....

SN1-type reaction The alkoxy group bonds to the more highly substituted carbon

a. In water to form glycols Protonation of oxygen (forming a good leaving group), followed by....

SN2 attack by water

second part of opening of epoxide 2. Base-catalysed

a. with alkoxides or hydroxide [The alkoxide ion simply attacks the less hindered carbon atom in an SN2 displacement] b. with organmetallics [Carbanion usually attacking the less hindered epoxide carbon atom: R bonds to the less substituted carbon]