Organic synthesis Flashcards
Describe the use of reflux
-technique used to heat volatile liquids
-reflux allows strong heating without losing volatile reactants and products. Volatile compounds evaporate and condense and fall back into the flask
-condenser has cold water running through. When hot evaporating substances hit the colder condenser, they return back into liquid and return to the round bottomed flask.
-heating is done via water bath as we are using flammable liquids
Describe the use of distillation?
-used when we want to separate substances with different boiling points
-gentle heating allows substances to separate in order of boiling point
-distillation is useful when you want to extract a chemical before it reacts any further
Describe the use of filtration
-vacuum creates a reduced pressure in the flask and pulls the liquid through. The solid will be left in the funnel.
Describe the use of recrystallisation
-method used to purify solids
-add enough hot solvent to allow the impure solid to dissolve. This means you will have a saturated solution of your impure product.
-allow solution to cool and crystals will form
-filter to get solid purified crystals. Wash with very cold solvent and dry them off
How do you determine boiling point of a liquid?
-use distillation set up
-the temperature in which the sample distils is the boiling point
-compare this boiling point against data booklet
-your sample contains impurities if your boiling point is higher than what is recorded in the data booklet
What is the disadvantage of using boiling point to spot impurities?
various compounds have the same boiling points. Other analytical techniques such as mass spectroscopy can be used.
Describe the use of melting points to determine purity of a substance?
-add sample to capillary tube and place into heating element of the melting point apparatus
-compare the temperature at which the substance melts to a data booklet
-if your substances contains impurities, the melting point will be lower.
what are the properties and typical reactions of alkanes, C-C?
properties- unreactive, non-polar bond
typical reaction- radical substitution
what are the properties and typical reactions of aromatic compounds, C6H5?
properties- delocalised electron ring, stable
typical reactions- electrophilic substitution
what are the properties and typical reactions of alkenes, C=C?
properties- electron rich double bond, non-polar bond
typical reaction- electrophilic addition
what are the properties and typical reactions of alcohols, C-OH?
properties- lone pair on oxygen can act as a nucleophile. C-OH bond is polar
typical reactions- esterification, nucleophilic substitution, dehydration/ elimination, nucleophilic substitution
what are the properties and typical reactions of haloalkanes?
properties- polar C-X bond
typical reactions- nucleophilic substitution and elimination
what are the properties and typical reactions of amines, C-NR2?
properties- lone pair on N is basic and can act as a nucleophile
typical reactions- nucleophilic substitution and neutralisation
what are the properties and typical reactions of nitriles, C-C(triple bond)N?
properties- electron deficient carbon centre
typical reactions- reduction and hydrolysis
what are the properties and typical reactions of aldehydes and ketones, C=O?
properties- polar C=O bond
typical reactions- nucleophilic addition, oxidation of aldehydes, reduction
