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Alkaloids, Evaporate, Evaporate, Ether +NaOH, Ether, Light petroleum ether…
Alkaloids
Properties
Colourless but few coloured
Crystalline
Non volatile
Solids but coniine and nicotine are liquids
Free basis -insoluble in water
Soluble in organic solvents
Mostly laevorotatory few dextro rotatory
Bitter in taste
Great value in medicine
Powerful poison
Nomenclature
According to source
Eg. Papaverine from papaver somniferum
According to physiological response
Eg. Morphin from Morphin (God of Dreams)
According to Discoverer
Eg. Pelleteriene from P.J Pelletier
Minor alkaloids named by adding prefix /suffix from their principal alkaloids
Classification
Taxonomic based
Eg. Cinchona
Pharmological based
Eg. Analgesic alkaloids
Bio synthetic based
Eg. Morphin
Chemical classification
True alkaloid
Contain heterocyclic nitrogen
Derived from amino acids
Proto /amino alkaloids
Simple amine
Pseudo alkaloids
Not derived from amino acids but from acyl CoA units
Eg. Conestine
Definition
Alkali like
Active basic compound of plant origin
Atleast one nitrogen atom forms part of cyclic system
Isolation
Finding the presence of alkaloid in plants using alkaloid reagent
Separating small amount of alkaloid from large amount of extraneous plant material
Separation and purification of individual alkaloids from crude material
Extraction
Powdered drug or macerated plant
FiltratIon
Filtrate
Fat
Plant residue
crude plant extract
Filtrate
Ether soluble
Basic material
Acid soluble
Aqueous residue
Ether :Solution
Crude alkaloids
Molecular structure determination
General methods
molecular formula determination
Emprical formula found by combustion analysis
Determination of unsaturation
By adding bromine /halogen acids /hydroxylation with KMnO4 /by reduction
Functional group determination
Hydroxyl group
(Acetic anhydride /Acetyl chlorides or Benzoate) +benzoyl Chloride gives Acetate
Determining amount of acetic anhydride or
Acetyl chlorides or Benzoate that reacted
with alcohol to form an ester, the no. Of
hydroxyl group is determined
Carboxyl group
Soluble in aqueous solutions of sodium carbonate or ammonia
With alcohol forms ester
Specific IR and NMR signal
No. Of COOH determined using titration
Carbonyl group
Aldehydes and ketones are detected by their reactions with hydroxylamine
Further confirmed by IR, UV, NMR
Methoxyl group
by Ziesel method
nature of nitrogen
Mostly secondary and tertiary
Nature of nitrogen is confirmed by degradation methods such as Hoffman Exhaustive Methylation
Evaporate
Evaporate
Ether +NaOH
Ether
Light petroleum ether
1.methanol
2.filteration
3.evaporate
: :
1.dissolve water
2.acidify topH 2
3.steam distillation
Evaporate