Lecture 1 - Science behind colour tests

Question 1

What is the marquis reagent a mix of?

Answer 1

2% formaldehyde in sulphuric acid

Question 2

What is the science behind a marquis reagent?

Answer 2

-The formaldehyde structure reacts with the benzene ring forming a primary carbocation
-Another of the same molecule is added producing a stable secondary carbocation

Question 3

What is the Ehrlic’s test a mix of?

Answer 3

1-pdimethylaminobenzaldehyde in conc HCL in ethylacetate

Question 4

What is the science behind the Ehrlic’s test?

Answer 4

-The LSD molecule reacts with the p-DMBA to form a corbinde
-Undergoes a condensation reaction and becomes unstable secondary carbocation
-A proton is added + further LSD molecules to form a stable tertiary carbocation

Question 5

What is the libermann’s test a mix of?

Answer 5

Potassium or Sodium nitrate in sulphuric acid

Question 6

What is the science behind the libermann’s test?

Answer 6

-Phenol groups react with the potassium or sodium nitrate & sulphuric acid to form a nitrosophenol
-More phenol molecules react with the sulphuric acid to form a coupled intermediate
-Loses water to form the product based on acidic or basic conditions

Question 7

What does the Duquenois-Levine test consist of?

Answer 7

-2% Vanillin + 1%actealdehyde in ethanol
-Concentrated HCL
-Chloroform

Question 8

What is the science behind the Duquenois-Levine test?

Answer 8

-THC undergoes adol condensation reaction
-Followed by an electrophillic aromatic substitution
-Results in a chromaphore structure

Question 9

What does the Dilli-Kopanyi test consist of?

Answer 9

-1% Cobalt acetate in methanol
-5% ispropylamine in methanol

Question 10

What is the science behind the Dilli-Kopanyi test?

Answer 10

Each reagant binds to the same cobalt atom to form a transition metal complex

Question 11

What is the science behind the simon test for methamphetamine?

Answer 11

-Methamphetamine binds to the acetaldehyde and loses water to form an emamine.
-This reacts with the nitroprusside and forms an ammonium salt
-Water is lost to form a simon awe complex

Question 12

What is the science behind the simon test for amphetamine?

Answer 12

-Amphetamine binds to the acetone and loses water to form an emamine.
-This reacts with the nitroprusside and forms an ammonium salt
-Water is lost to form a simon awe complex

Question 13

What is the science behind the fast blue BB salt test?

Answer 13

-Coupling reaction between diazonium group of fast blue BB salt + activating phenol groups