Allyl isothiocyanate, Hydrocyanic acid (HCN)=Prussic acid, indole and skatole

1. Phytochemistry
Volatile oils
Organo-nitrogen and organo-sulphur
compounds
By
Dr. Mostafa Mahmoud Hegazy ( PH.D.)

2. Organo-nitrogen and organo-sulphur compounds in
volatile oils
Occurrence: albuminous matter (e.g. seeds) yield on distillation volatile
N or S compounds, which can be detected in volatile oils.
Rectification or "double- distillation "of essential oils
Organo-sulphur compounds: As degradation products of thioglycosides
during steam distillation of the oils.
Examples are:
- Hydrogen sulphide, H2S, in unrectified oils of anise and caraway.
- Diallyldisulfide, in oils of onions and garlic.
- Allyl isothiocyanate (mustard oil).
S
S
C
H
H2
C CH2
H
C
C
H2
H2C
Diallyl disulfide
C
H
H2
CH2C C
N
S
Allyl isothiocyanate

3. Allyl isothiocyanate
Source: oil of the black mustard & radish.
Preparation:
1- Defatted black mustard seeds are macerated.
2- Steam distillation.
3- The oily layer (heavier than H2O) collected over CaCl2.
4- Rectification by fractional distillation collecting the portion boiling between 145-152 o
C.
Properties: yellow strongly refractive liquid, with irritating odor with lachrymatory
effect and an acid pungent taste. It is sparingly soluble in water but soluble in organic
solvents. It decomposes on exposure to light and air and should be stored in dark
well-filled bottles.
Uses:
1- Flavoring for food products.
2- Locally, as rubefacient or vesicant in certain plasters. Expressed mustard oil a less
powerful counter-irritant.
3- Internally it causes Sever GIT irritation.
C
H
H2
CH2C C
N
S
C
H
H2
CH2C N
C
O.SO2.OK
S.C6H12O6
Sinigrin Allyl isothiocyanate Potassium
acid sulfate
H2O
Myrosin
+ C6H12O6 + KHSO4
Glucose

4. Allyl isothiocyanate determination(Volhard's method)
oil + AgNO3 excess
NH3
Ag2S ppt
filtered

5. Organo-nitrogen compounds
Hydrocyanic acid (HCN)=Prussic acid
It occurs in Bitter almond in glycosidal form as amygdalin and prunasin
Identification
1- Prussian-blue test :Crush the plant material, macerate in warm water,
acidify with H2SO4 (hydrolysis) and steam distill.
•Shake a small amount of the distillate with few drops of NaOH solution.
•Add a few drops of FeSO4 / Fe2O3, shake and acidify with dilute HCl. A
characteristic blue precipitate of ferric ferrocyanide is formed.
2- Guignard’s paper test: A Filter moistened with picric acid and sod.
carbonate (yellow sod. picrate paper )is fixed into test tube of crushed plant
material→ red sod. Picramate paper(one nitro gp. Being reduced to amino
gp.)

6. Prussic acid determination
cyanide + silver nitrate
10% KCrO4 indicator
ppt
end point… red color of silver chromate.

7. Source: oils of jasmine, neroli, lemon flower
1- wood Celtis reticulosa
(Ulmaceae),
2- In human excrements as a result
of decomposition of albuminous
matter.
3- It is formed when strychnine is
heated with soda lime.
- oil of Lipidium sativum,
Cruciferae and in oil of
neroli.
Isolation:By formation of its picrate salt that is
obtained as lustrous red needles (m. p. 176 -
177 º C).
Through its crystalline picrate
derivative.
Properties
It has a powerful, persistent, disagreeable odor
especially if not purified (synthetic product).
If pure and strongly diluted it has a flowery,
heavy odor which is not more disagreeable.
- It is heavier than
water.
Uses:in traces, in perfumes of heavy oriental
types, and as a fixative.
in minute amounts as a Fixative.
N
Indole
N
CH3
Skatole
CH2CN
Benzyl cyanide

8. For more educational lectures
cognosy4all.blogspot.com

9. cognosy4all.blogspot.com
Pharmacognosy and Herbal Medicine Dr. Mostafa

10. cognosy4all.blogspot.com
Pharmacognosy and Herbal Medicine Dr. Mostafa