all organic synthesis pathways Flashcards
describe the 3 steps of free-radical substitution with halogens.
1) initiation
- produces free radical from molecules
2) propagation
- forms products & more radicals
3) termination
- removes free radicals
under what conditions does alkanes react with halogens?
under UV light / on heat
what reaction conditions are involved in the electrophilic addition of H2 to alkenes? what is the product?
Ni catalyst, 150C, 5 atm
forms alkanes
what reaction conditions are involved in the electrophilic addition of steam to alkenes? what is the product?
conc. H3PO4 catalyst, 300-600C, 70 atm
produce alcohols
what reaction conditions are involved in the oxidation of alkenes? what is the product?
acidified KMnO4 + steam
produce diols
what are the reagents, conditions & mechanism of bromination of benzenes?
mechanism: electrophilic substitution
reagent: Br2
conditions: room temp. & FeBr3 catalyst
draw the mechanism of electrophilic substitution of benzenes with bromine. *
draw the mechanism of nitration of benzenes. *
what are the reagents, conditions & mechanism of chlorination of benzenes?
mechanism: electrophilic substitution
reagent: Cl2
conditions: room temp. & FeCl3 / AlCl3 catalyst
what are the reagents, conditions & mechanism of nitration of benzenes?
mechanism: electrophilic substitution
reagents: conc. HNO3 & conc. H2SO4 catalyst
conditions: below 55C
what is the mechanism of friedel-crafts reactions?
electrophilic substitution
what are the reagents and conditions of friedel-crafts alkylation?
reagent - RCl (chloroalkyl compound)
conditions - anhydrous AlCl3 catalyst
- heat under reflux
draw the mechanism of friedel-crafts alkylation. *
what are the reagents & conditions of friedel-crafts acetylation?
reagents - acyl chloride
conditions - anhydrous AlCl3 catalyst
- heat under reflux at 50C
draw the mechanism of friedel-craft acetylation. *
describe the reagents and conditions of bromination of phenols.
reagents - bromine water
conditions - room temp.
draw the mechanism of bromination of phenols. *
why does phenols not require a halogen carrier?
lone pair on O on -OH group is partially delocalised in the ring & activates the ring
-> higher e- density & Br2 is more polarised
how could 2,4,6-tribromophenol be identified?
white solid, antiseptic smell
how could primary amines be formed from halogenoalkanes?
one-step nucleophilic substitution
how could primary amines be prepared from nitriles?
1- convert halogenoalkane to nitrile
reagent- ethanol & KCN
conditions - heat under reflux
2- reduce nitrile to amine
reagent- LiAlH4 in dry ether
how are aromatic amines formed from nitroarenes?
reagent- Sn & HCl
conditions - heat
mechanism - reduction
what does grignard reagents do?
increase carbon chain length
how are grignard reagents made?
halogenoalkane dissolved in dry ether & reacted with Mg
what does grignard reagent & methanal form?
primary alcohol
what does grignard reagent & aldehyde form?
secondary alcohol
what does grignard reagent & carbon dioxide form?
carboxylic acid
what are the conditions and reagents of oxidation of aldehydes? what is the product?
carboxylic acid
- heat under reflux
- K2Cr2O7 & dilute H2SO4
what compound could be tested with fehling’s solution? state the conditions, reagents & observation.
aldehydes
condition: heat gently
reagents: solution with Cu2+ ions
observation: Cu2+ ions reduced to CuO (red ppt)
(& aldehydes oxidised to carboxylic acids)
what compound could be tested with tollen’s reagent? state the conditions, reagents & observation.
aldehydes
condition: heat gently
reagents: aq, NH3 + AgNO3 -> complex ion [Ag(NH3)2]+
observation: silver mirror forms as Ag+ (aq) reduced to Ag(s))
(& aldehydes oxidised to carboxylic acids)
what is the reagents & conditions of reduction of carbonyls?
reagents: LiAlH4 in dry ether / reduction agent
conditions: room temp. & Pa
what would aldehydes & ketones be reduced to?
aldehyde: primary alcohols
ketones: secondary alcohols
what are formed with nucleophillic addition of carbonyls?
hydroxynitriles
what are the reagents & conditions of nucleophillic addition of carbonyls? draw the mechanism.
reagent: HCN in presence of KCN
conditions: room temp. & Pa
what is the iodoform test specifically for?
carbonyls with methyl group attached next to C=O (ethanal / methyl ketones)
what are the reagents & conditions of the iodoform test?
reagents - I2 with NaOH (alkali)
conditions - warm gently
what is formed in the iodoform test? state the formula and the observations.
CHI3, triiodomethane
yellow ppt
