Organic Chemistry Flashcards
Suggest a reason why some reactions occur by a mechanism involving a carbocation where others do not
Reactions involving carbocations tend to be tertiary carbocations since they are more stable than primary carbocations
Conditions of producing ethanol from ethene
- CONCENTRATED phosphoric acid catalyst
- high temperature
- high pressure
Suggest and explain a reason why an alcohol might not be easily oxidised
Tertiary alcohol so has no hydrogens on carbon attached to -OH for oxygen to remove
Give reasons why a major product for a reaction is formed
Formed from a tertiary/secondary carbocation which is more stable because :
- more alkyl groups bonded to carbon
- donate electron density (inductive effect) for greater stability
Suggest what physical properties of a homologous series change as chain length increases
Boiling / Melting Point
Density
Viscosity
Reason for E/Z isomerism
Restricted rotation around C=C bond
Suggest why alkenes do not react with warm aqueous sodium hydroxide
OH- acts as a nucleophile so high electron density of double bond repels it
Suggest reasons why ethene is not made from elimination reactions of haloalkanes in industry
- halogenoalkanes are expensive/ not readily available
- low yield
- slow reaction
What is meant by propagation step
Radicals formed and used
Suggest why haloalkanes are susceptible to attacks by nucleophiles
Bond between halogen and carbon is polar
Carbon atom is electron deficient/ partially positive
Features of a homologous series
- gradual change in physical properties as relative molecular mass increases
- same chemical properties
- same functional group
- same general formula
Suggest an economic reason for cracking fractions of crude oil
Meet high demand of more useful/ high value products which are in low supply using less useful products
Nucleophile + Electrophile
- nucleophile = electron pair donor
- electrophile = electron pair acceptor
Production of ethanol by hydration
- electrophilic addition reaction
- continuous process
- low percentage yield since reversible
- high atom economy (no waste products/ ethanol only product)
- unsustainable since ethene is finite (comes from crude oil)
- requires energy to produce steam
Production of ethanol by fermentation
- anaerobic respiration of yeast
- high percentage yield
- low atom economy since carbon dioxide water product
- sustainable since crops are renewable
- energy required for distillation
Suggest why distillation produces aldehydes
- volatile components can escape / distill off
- partial oxidation
Suggest why reflux produces carboxylic acids
- volatile components cannot escape so are refluxed
- complete oxidation
Suggest what the other product of oxidation of alcohols is
Water (always one mole - even when carboxylic acid is produced)
Conditions for production of ethanol by fermentation
- enzymes (yeast)
- anaerobic
- 25 - 42 degrees C
Suggest how you can tell when fermentation of glucose is complete
No more bubbles suggesting carbon dioxide is not produced