B3.6 - Organic synthesis
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Draw a diagram of the set up for refluxing reactions.
water out at top water out at bottom condenser flask reaction mixture anti-bumping granules upwards arrow heat (bunsen) VERTICAL
What is the role of anti-bumping granules?
Anti-bumping granules are added to the flask to prevent violent boiling
What is the role of the condeser?
The condenser has cold water flowing through it, which condenses evaporated organic vapours back into liquid, returning them to the reaction in the flask
What does refluxing allow?
process allows the organic substances to be heated to their boiling point, speeding up the reaction, without losing material
Draw a diagram of the set up for distillation.
thermometer water out at top water in at bottom condenser round bottomed flask filled with reaction mixture anti-bumping granules upwards arrow heat (bunsen) conical flask - filled with distillate DIAGONAL
What is the role of the thermometer during distillation?
A thermometer is used to monitor the boiling point of the distilling vapour - helps to identify the substance evaporating
Techniques to purify an organic liquid: 1 redistillation
Repeated distillation helps to separate the pure volatile liquid product from impurities with different boiling points The pure product distils over at its characteristic boiling point, leaving impurities behind
Techniques to purify an organic liquid: 2 extraction
When water is added to a mixture of the organic liquid and an organic solvent in a separating funnel, two immiscible layers form The organic liquid product dissolves in the organic layer, while water-soluble impurities dissolve in the aqueous layer The layers are then drained off separately from the tap at the bottom of the funnel
Techniques to purify an organic liquid: 3 drying
Traces of water dissolved in organic products can be removed using drying agents
What are examples of drying agents - for drying organic compounds?
anhydrous magnesium sulphate anhydrous calcium chloride
Techniques to purify an organic liquid: 4 filtration
After drying, the solid drying agent is removed by filtering the mixture, leaving behind the dry purified organic product
What does a synthetic route outline?
outlines the sequence of reactions needed to transform starting materials into the desired end product
What does a synthetic route detail?
• Every chemical intermediate formed along the way • The specific reagents and conditions required at each stage of the process
Alkane –> halogenoalkane: reagent + condition + reaction type
reagent - halogen condition - UV reaction type - free radical substitution
Alkene –> alkane: reagent + condition + reaction type
reagent - H2 condition - Ni catalyst, 150 degrees C reaction type - electrophilic addition
Alkene –> halogenoalkane: reagent + reaction type
reagent - hydrogen halide or halogen reaction type - electrophilic addition
Halogenoalkane –> alcohol: reagent + condition + reaction type
reagent - NaOH(aq) condition - reflux reaction type - nucleophilic substitution
alcohol –> halogenoalkane: reagent + condition + reaction type
reagent - sodium halide, H2SO4 condition - reflux reaction type - nucleophilic substitution
alkene –> alcohol: reagent + condition + reaction type
reagent - steam condition - H3PO4 catalyst, 300 degrees C, 60 atm/reflux reaction type - electrophilic substitution
alcohol –> alkene: condition + reaction type
condition - conc. H2SO4, heat/reflux reaction type - elimination
alcohol –> carboxylic acid/ketone: reagent + condition + reaction type
reagent - K2Cr2O7(aq) condition - H2SO4 catalyst, reflux reaction type - oxidation
alcohol –> aldehyde: reagent + condition + reaction type
reagent - K2Cr2O7(aq) condition - H2SO4 catalyst, distill reaction type - oxidation
Properties and typical reactions of alkanes
non-polar, unreactive free radical substitution
Properties and typical reactions of alkenes
non-polar, electron-rich electrophilic addition