45 Questions
What is the purpose of Wagner's and Dragendorff's reagents in alkaloid analysis?
To form precipitates with alkaloids
How is caffeine typically detected in alkaloid analysis?
By reacting with potassium chlorate and hydrochloric acid
Which amino acid involved in alkaloid biosynthesis has its COOH & NH2 groups on different carbon atoms?
Lysine
What is the significance of decarboxylation and transamination in alkaloid biosynthesis?
To form amines from amino acids
What kind of test is the murexide test used for in alkaloid analysis?
Detection of purine derivatives
How do proteins behave during the evaporation process in alkaloid extraction?
Some proteins remain unextracted
In alkaloid biosynthesis, what type of reaction can follow the formation of a Schiff base?
Mannich type of condensation
How are alkaloids detected through the general reactions in biosynthesis?
By reacting to form carbanions.
What happens to proteins during the evaporation process in alkaloid extraction?
Some remain unextracted, while others become insoluble.
What distinguishes anthranilic acid from other amino acids involved in alkaloid biosynthesis?
The position of COOH & NH2 groups on different carbons.
What is the primary function of Wagner's and Dragendorff's reagents in alkaloid analysis?
To form precipitates with alkaloids.
What is the purpose of moistening the powdered material with alkaline substances in alkaloid extraction method A?
To combine with acids and phenolic substances
In alkaloid extraction method A, why is the concentrated organic liquid shaken with aqueous acid?
To separate alkaloid salts into the aqueous phase
How are impurities removed from the organic liquid in alkaloid extraction method A?
Shaking with aqueous acid
What is the main purpose of the addition of excess alkalis like sodium bicarbonate in alkaloid extraction method B?
To precipitate the free alkaloids
Why are chloroform or other organic solvents added and shaken in method B of alkaloid extraction?
To remove pigments and unwanted materials
What happens to the free alkaloids after they are precipitated by excess alkalis in method B of alkaloid extraction?
They are separated by filtration or organic solvent extraction
What is a common issue that may arise during the extraction of alkaloids, as mentioned in the text?
Some proteins not being extracted
How is caffeine typically detected in alkaloid analysis as described in the text?
By reacting with hydrochloric acid and potassium chlorate
Which amino acid involved in alkaloid biosynthesis differs from others because its COOH & NH2 groups are not on the same carbon atom?
Phenylalanine
What color change indicates a positive murexide test, as explained in the text?
Purple
Which general reaction is highlighted as particularly important in the biosynthesis of many alkaloids?
Schiff base formation
What distinguishes caffeine from most alkaloids in terms of precipitation?
Caffeine does not precipitate like most alkaloids
In Method A of alkaloid extraction, the powdered material is moistened with acidic substances to set free the alkaloid bases.
False
Organic solvents such as water or aqueous alcohol are used in Method A of alkaloid extraction.
False
In Method B of alkaloid extraction, excess alkalis like sodium bicarbonate or ammonia are added to precipitate the free alkaloids.
True
A positive murexide test indicates the presence of alkaloid salts in the organic liquid.
False
Chloroform is used in Method B of alkaloid extraction to remove pigments and unwanted materials.
True
Proteins in alkaloid extraction behave differently during the evaporation process in Methods A and B.
False
In alkaloid extraction, aqueous acid is used to separate the free alkaloids from the concentrated organic liquid.
False
Calcium hydroxide can be used as an alkaline substance for moistening the powdered material in alkaloid extraction.
True
In Method A of alkaloid extraction, the impurities remain behind in the aqueous liquid after shaking with organic solvents.
False
Alkaloidal salts are found in the organic liquid after shaking with aqueous acid in Method A of alkaloid extraction.
False
Method B of alkaloid extraction involves the precipitation of free alkaloids by adding excess acids like hydrochloric acid.
False
In both Method A and Method B of alkaloid extraction, organic solvents are used for the extraction process.
True
In Alkaloid Extraction, Method A involves moistening the powdered material with acidic substances.
False
Organic solvents such as water or aqueous alcohol are used in Method A of alkaloid extraction.
False
Chloroform is added and shaken in Method B of alkaloid extraction to remove pigments and unwanted materials.
True
Aqueous acid is used to separate the free alkaloids from the concentrated organic liquid in alkaloid extraction.
True
Calcium hydroxide is not used as an alkaline substance for moistening the powdered material in alkaloid extraction.
False
Extraction in Method B of alkaloid extraction is carried out with ether or petroleum spirit.
False
In both Method A and Method B of alkaloid extraction, acidic substances are added to set free the alkaloid bases.
False
After shaking with aqueous acid, alkaloidal salts are found in the organic liquid in Method A of alkaloid extraction.
False
Method B of alkaloid extraction involves separating impurities by shaking with aqueous acid.
False
The free alkaloids in Method B of alkaloid extraction are precipitated by adding excess acids.
False
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