C28 - Organic synthesis Flashcards
What is the nitrile functional group
-CN
(C to N triple bond)
How can nitriles be formed from haloalkanes?
Haloalkane + KCN —> -nitrile + KCl
How do you name nitriles?
Identify longest carbon chain (becomes prefix +an)
Add nitrile as suffix
What is the reaction mechanism for forming nitriles from haloalkanes
Nucleophilic substitution
How can you form nitriles from aldehydes/ketones
+HCN —> hydroxynitrile
HCN is poisonous so KCN + H2SO4 used
What is the reaction mechanism for ketones/aldehydes to nitriles
Nucleophilic addition
Reduction of nitriles
Nitrile + H2 —> amine
Ni catalyst
Hydrolysis of nitriles
Nitrile + H2O + HCl —> Carboxylic acid + ammonium chloride
Heat (w dilute acid-HCl)
How can you form carbon to carbon bonds in benzene rings?
Acylation
Alkylation
How can you prepare an organic solid?
1) Filter under reduced pressure
2) Recrystalisation
3) Melting point determination
What is filtering under reduced pressure used for?
Separates solid product from solvent/liquid mixture
How can you carry out filtration under reduced pressure?
1) Set up Büchner flask so that the arm is connected by rubber tubing to a vacuum pump
2) Fit Buchner funnel to flask tightly
3) Place filter paper on funnel and moisten it with solvent
4) Turn on vacuum pump
5) Slowly pour mixture into funnel, rinse flask and funnel with solvent and then allow to dry
What is the purpose of recrystallisation?
Solid product obtained after filteration will contain impurities which will be removed
How do you carry out recrystalisation
1) Heat solvent
2) Pour minimum volume of hot solvent required to dissolve the sample
3) Allow solution to cool to room temp, and then an ice bath
4) Then, filter under reduced pressure again
What is the purpose of melting point determination?
Identify whether a solid compound is pure - should have sharp temperature at which it melts
How do you carry out melting point determination?
1) take glass capillary/melting point tube
2) filled with crystals (tapped in) to about 3mm depth
3) Melting point can be taken 1 of 2 ways…
Electrically heated melting point apparatus
1) place capillary tube into sample hole and thermometer into thermometer hole
2)heat using rapid heat setting
3) record temperature at which sample melts
4) repeat, heating slowly when previously recorded temperature approaches
Using oil bath/Thiel tube method…
1) Set up thiele tube/ oil bath
2) Attach capillary tube containing sample to thermometer using rubber band
3) insert thermometer thru whole in crock/clamp thermometer for oil bath - end of thermometer and capillary tube should be dipped in oil
4) using micro-burner, slowly heat side arm of thiele tube/oil bath
5) when oil begins to melt , remove heat, note when all sold melted
Reactions of main functional groups.
Reactions of benzene and its derivatives
Reactions of phenols and its derivatives
