Alkaloids

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Questions and Answers

What is the purpose of Wagner's and Dragendorff's reagents in alkaloid analysis?

  • To make proteins insoluble during evaporation
  • To extract alkaloids from the plant
  • To form precipitates with alkaloids (correct)
  • To detect the presence of proteins

How is caffeine typically detected in alkaloid analysis?

  • By mixing with ammonia vapor
  • By evaporation to dryness and exposure to carbon dioxide
  • By reacting with Dragendorff's reagent
  • By reacting with potassium chlorate and hydrochloric acid (correct)

Which amino acid involved in alkaloid biosynthesis has its COOH & NH2 groups on different carbon atoms?

  • Lysine (correct)
  • Ornithine
  • Phenylalanine
  • Tyrosine

What is the significance of decarboxylation and transamination in alkaloid biosynthesis?

<p>To form amines from amino acids (A)</p> Signup and view all the answers

What kind of test is the murexide test used for in alkaloid analysis?

<p>Detection of purine derivatives (C)</p> Signup and view all the answers

How do proteins behave during the evaporation process in alkaloid extraction?

<p>Some proteins remain unextracted (A)</p> Signup and view all the answers

In alkaloid biosynthesis, what type of reaction can follow the formation of a Schiff base?

<p>Mannich type of condensation (A)</p> Signup and view all the answers

How are alkaloids detected through the general reactions in biosynthesis?

<p>By reacting to form carbanions. (D)</p> Signup and view all the answers

What happens to proteins during the evaporation process in alkaloid extraction?

<p>Some remain unextracted, while others become insoluble. (B)</p> Signup and view all the answers

What distinguishes anthranilic acid from other amino acids involved in alkaloid biosynthesis?

<p>The position of COOH &amp; NH2 groups on different carbons. (D)</p> Signup and view all the answers

What is the primary function of Wagner's and Dragendorff's reagents in alkaloid analysis?

<p>To form precipitates with alkaloids. (D)</p> Signup and view all the answers

What is the purpose of moistening the powdered material with alkaline substances in alkaloid extraction method A?

<p>To combine with acids and phenolic substances (C)</p> Signup and view all the answers

In alkaloid extraction method A, why is the concentrated organic liquid shaken with aqueous acid?

<p>To separate alkaloid salts into the aqueous phase (A)</p> Signup and view all the answers

How are impurities removed from the organic liquid in alkaloid extraction method A?

<p>Shaking with aqueous acid (A)</p> Signup and view all the answers

What is the main purpose of the addition of excess alkalis like sodium bicarbonate in alkaloid extraction method B?

<p>To precipitate the free alkaloids (B)</p> Signup and view all the answers

Why are chloroform or other organic solvents added and shaken in method B of alkaloid extraction?

<p>To remove pigments and unwanted materials (D)</p> Signup and view all the answers

What happens to the free alkaloids after they are precipitated by excess alkalis in method B of alkaloid extraction?

<p>They are separated by filtration or organic solvent extraction (C)</p> Signup and view all the answers

What is a common issue that may arise during the extraction of alkaloids, as mentioned in the text?

<p>Some proteins not being extracted (D)</p> Signup and view all the answers

How is caffeine typically detected in alkaloid analysis as described in the text?

<p>By reacting with hydrochloric acid and potassium chlorate (C)</p> Signup and view all the answers

Which amino acid involved in alkaloid biosynthesis differs from others because its COOH & NH2 groups are not on the same carbon atom?

<p>Phenylalanine (B)</p> Signup and view all the answers

What color change indicates a positive murexide test, as explained in the text?

<p>Purple (D)</p> Signup and view all the answers

Which general reaction is highlighted as particularly important in the biosynthesis of many alkaloids?

<p>Schiff base formation (A)</p> Signup and view all the answers

What distinguishes caffeine from most alkaloids in terms of precipitation?

<p>Caffeine does not precipitate like most alkaloids (D)</p> Signup and view all the answers

In Method A of alkaloid extraction, the powdered material is moistened with acidic substances to set free the alkaloid bases.

<p>False (B)</p> Signup and view all the answers

Organic solvents such as water or aqueous alcohol are used in Method A of alkaloid extraction.

<p>False (B)</p> Signup and view all the answers

In Method B of alkaloid extraction, excess alkalis like sodium bicarbonate or ammonia are added to precipitate the free alkaloids.

<p>True (A)</p> Signup and view all the answers

A positive murexide test indicates the presence of alkaloid salts in the organic liquid.

<p>False (B)</p> Signup and view all the answers

Chloroform is used in Method B of alkaloid extraction to remove pigments and unwanted materials.

<p>True (A)</p> Signup and view all the answers

Proteins in alkaloid extraction behave differently during the evaporation process in Methods A and B.

<p>False (B)</p> Signup and view all the answers

In alkaloid extraction, aqueous acid is used to separate the free alkaloids from the concentrated organic liquid.

<p>False (B)</p> Signup and view all the answers

Calcium hydroxide can be used as an alkaline substance for moistening the powdered material in alkaloid extraction.

<p>True (A)</p> Signup and view all the answers

In Method A of alkaloid extraction, the impurities remain behind in the aqueous liquid after shaking with organic solvents.

<p>False (B)</p> Signup and view all the answers

Alkaloidal salts are found in the organic liquid after shaking with aqueous acid in Method A of alkaloid extraction.

<p>False (B)</p> Signup and view all the answers

Method B of alkaloid extraction involves the precipitation of free alkaloids by adding excess acids like hydrochloric acid.

<p>False (B)</p> Signup and view all the answers

In both Method A and Method B of alkaloid extraction, organic solvents are used for the extraction process.

<p>True (A)</p> Signup and view all the answers

In Alkaloid Extraction, Method A involves moistening the powdered material with acidic substances.

<p>False (B)</p> Signup and view all the answers

Organic solvents such as water or aqueous alcohol are used in Method A of alkaloid extraction.

<p>False (B)</p> Signup and view all the answers

Chloroform is added and shaken in Method B of alkaloid extraction to remove pigments and unwanted materials.

<p>True (A)</p> Signup and view all the answers

Aqueous acid is used to separate the free alkaloids from the concentrated organic liquid in alkaloid extraction.

<p>True (A)</p> Signup and view all the answers

Calcium hydroxide is not used as an alkaline substance for moistening the powdered material in alkaloid extraction.

<p>False (B)</p> Signup and view all the answers

Extraction in Method B of alkaloid extraction is carried out with ether or petroleum spirit.

<p>False (B)</p> Signup and view all the answers

In both Method A and Method B of alkaloid extraction, acidic substances are added to set free the alkaloid bases.

<p>False (B)</p> Signup and view all the answers

After shaking with aqueous acid, alkaloidal salts are found in the organic liquid in Method A of alkaloid extraction.

<p>False (B)</p> Signup and view all the answers

Method B of alkaloid extraction involves separating impurities by shaking with aqueous acid.

<p>False (B)</p> Signup and view all the answers

The free alkaloids in Method B of alkaloid extraction are precipitated by adding excess acids.

<p>False (B)</p> Signup and view all the answers

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