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Sterochemistry of menthol

Page history last edited by aboody_hot@hotmail.com 9 years, 5 months ago

Steriochemistry of menthol:

Objective: Determine the configuration of Chiral C atoms in each stereoisomer of menthol.

-          Menthol has 8 stereoisomers. They also  have different characteristics.

   

 
                                                                                
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Note: that the missed bond are bonds with H.

-          (L) -  menthol and (D) – menthol are mirror images and not superimposable , thus they are enantiomers and that's why they have same melting points ( since enantiomers have same physical properties).

Characteristics of each stereoisomer of menthol. 

(-) neomenthol

(+) neomenthol

Minty  - musty – fresh – earthy campherous – some cooling

Taste threshold = 600 ppb

Cooling threshold = 25000 ppb

Minty  - musty – fresh – some cooling - sweet

Taste threshold = 500 ppb

Cooling threshold = 2500 ppb

(-) menthol

(+) menthol

Very cooling – sweet – fresh - minty

Taste threshold = 400 ppb

Cooling threshold = 800 ppb

Fresh – cooling – minty with musty – bitter

Taste threshold = 300 ppb

Cooling threshold = 3000 ppb

(-) isomenthol

(-) isomenthol

Musty - sweet– hay – earthy camphoraceous – herbaceous – slight cooling.

Taste threshold = 600 ppb

Cooling threshold = 30000 ppb

Musty – woody – fresh – carrot minty -  earthy camphoraceous –slight cooling.

Taste threshold = 700 ppb

Cooling threshold = 7000 ppb

(-) neoisomenthol

(+) neoisomenthol

Minty – earthy – woody – camphoraceous – sweet – minty – slight cooling

Taste threshold = 1000 ppb

Cooling threshold = 6000 ppb

Minty – earthy – woody – camphoraceous – carrot – minty – herbaceous - very little cooling

Taste threshold = 200 ppb

Cooling threshold = 25000 ppb

 

R or S Menthol?

Answers: 

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