functional group conversions

what are alkyl halides used to access

a wide range of functional groups via nucleophilic substitution

why is a halide a good leaving group

it is electron withdrawing

what are the different things an alkyl halide can be converted into

• alcohols

• ethers

• thiols

• sulfides

• nitriles

• secondary amines

• acetylenes

• azides

what are the different types of alkyl halides synthesis 

• alcohols and strong acids 

• alcohols and thionyl chloride (SOCl2)

• halide exchange (Finkelstein reaction)

• alkenes and strong (dry) acids 

why does the alkyl halide synthesis of alcohols and strong acids only work well with tertiary alcohols

• the intermediate of the reaction is stabilised because the groups are electron withdrawing

• SN1 reaction

what is the first part of an alcohol and thionyl chloride (SOCl2) mechanism the same as

the acyl chloride mechanism 

why is chlorine a good leaving group in an alcohol and thionyl chloride reaction 

due to the stability of the rest of the molecule 

why is a tertiary alcohol the most difficult to react 

• due to the steric hinderance 

what are the common reactions of alcohols

• ketones (from secondary ROH)

• aldehyde (from primary OH)

• carboxylic acid

• esters

• sultanate esters

• phosphate esters

• ethers

• alkyl halides

• alkenes

why are ethers normally difficult to hydrolyse

there is no leaving group on C-O

why are phosphate esters more acidic than carboxylic acids 

due to the delocalisation 

how to produce an alcohol from a carboxylic acid

• LiAlH4 needed

• one of the strongest reducing agents 

how to produce an alcohol from an ester

acid chloride 

how to produce an alcohol from a sultanate ester

sulfanol chloride 

how to produce an alcohol from a phosphate ester

phosphanol chloride

what do strong oxidants convert primary alcohols into 

• carboxylic acids

• via the aldehyde, which is rapidly oxidised by KMnO4

what can primary alcohols be oxidised into 

• aldehydes using milder swern oxidation conditions

what are secondary alcohols oxidised into

• ketone only

• via aldehyde or via swern oxidation

what is the overall reaction of a swern oxidation

• alcohol oxidised to aldehyde/ketone 

• the DMSO (sulfoxide) reduced to dimethyl sulphide (Me2S)

why is DMSO a good biological solvent 

• chemically insert 

• can be dissolved in water 

aldehyde common reactions

• imine (primary amine)

• alcohol (reduction)

• carboxylic acid (oxidation KMnO4)

• secondary alcohol (R-MgBr)

• ester

• acetal

ketone common reactions

• imines (primary amines)

• secondary alcohol

• tertiary alcohol (R-MgBr)

• ketals (KOH/H+)

• esters

why is a carboxylate a good leaving group in the Baeyer villiger oxidation

stabilisation of the negative charge

what is the Baeyer villiger oxidation

conversion of a ketone to an ester 

what does a per-acid look like

carboxylic acid with an extra oxygen

what are per-acids

• oxidisers

• the alkyl equivalent of hydrogen peroxide 

why are per-acids very nucleophilic

due to the repulsion between adjacent atoms with lone pairs (the alpha effect)

if a ketone is non-symmetrical what does it produce in a Baeyer villiger oxidation

a major and minor product

where does the per-acid insert itself in a non-symmetrical ketone

the most substituted part

what are the common reactions of an ester

• carboxylic acid (H+/H2O or NaOH)

• amide (primary amine and heat)

• tertiary alcohol (R’MgBr)

• alcohol (LiAlH4)

• aldehyde (DIBAL at -78 degrees)

• ketone (if R’O- is in vast excess you’ll get complete conversion: TRANS-ESTERIFICATION)

what is DIBAL

• di-isobutyl aluminium hydride 

• sterically hindered and weaker reducing agent than LiAlH4

what can DIBAL prevent the reduction of 

intermediate aldehyde if reaction carried out at very low temperatures (-78 degrees)

what are some common reactions of carboxylic acids 

• thioesters (RSH + coupling reagents)

• esters (ROH + coupling reagents)

• amides (RNH2 + coupling reagents)

• anhydrides (condensation)

• primary alcohol (LiAlH4)

• acid chloride (SOCl2)

why cant a primary amine be used on its own to convert a carboxylic acid into an amide

the amine deprotonates the acid and on its own it will just produce a salt

why is a carboxylic acid not very nucleophilic

because of delocalisation

what is the order of other ester/amide-like derivatives with decreasing reactivity and increasing stability. start with most reactivity and least stability 

• acid chloride (string electron withdrawing group)

• thioesteer

• ester 

• amide (donates a bit of its charge neutralising the carbon and doesn’t make itself a good leaving group)

• carbamate

• carboxylic acid (good at stabilising a negative charge so it repels a nucleophile)

sulfur based functional groups

• thiol (R-SH)

• Sulfide (R-S-R)- not very reactive

• sulfoxide (R-S=O-R)

• sulfone (R-O=S=O-R)- sulfur is a large molecule and can have a valency of 6

• disulphide (R-S-S-R)

• Sulfonic acid

• sultanate ester

• sulfonamide

• sulfonyl chloride 

• thioester

what are the common valencies for S in organosulfur groups

• 2

• 4

• 6

why are sulfoinic acids very acidic

negative charge delocalised across 4 atoms

what shapes are sulfides, sulfoxides, and sulfones

• tetrahedral 

• sulfoxides can be chiral 

what do sulfonyl chlorides react with

• amines

• alcohols

• alkoxides 

• same mechanism as acid chlorides 

where does the nucleophilic attack occur on a sultanate ester

at the first carbon on the O-alkyl component

why is a sultanate an excellent leaving group

because of the steric hinderance

what is an effective way to activate alcohols

using sulfonate esters

sultanate esters common reactions 

• azides

• alcohols

• ethers

• thiols

• sulfides

• nitriles

• acetylenes

what are thiols more acidic than

alcohols

what can thiols oxidise to

disulfides into milder conditions

what do thiols readily equilibrate with

bisulfides by thiol-disulphide exchange