Structure and Synthesis

1. Vitamin K

2. Vitamin K
• Vitamin K is the only fat soluble vitamin with a specific
coenzyme function
• It is required for the production of blood clotting
factors, essential for coagulation (in German –
Koagulation; hence called as vitamin K)
Chemistry:
• Vitamin K exists in different forms
• Vitamin - K1 (phylloquinone)
• Vitamin - K2 (menaquinone)
• Vitamin - K3 (menadione)

3. Structure
• All the three vitamins ( K1, K2, K3 ) are
naphthoquinone derivatives

4. vitamin K1 and vitamin K2 are both 2-methyl-1,4-naphthoquinone (3-)
derivatives, they have similar metabolic pathways during reactions.
Overall, vitamin K contains a functional naphthoquinone ring and an
aliphatic side chain.
Vitamin K1 has a phytyl side chain attached to the homolog while
vitamin K2 are composed of menaquinones that are made up of varying
numbers of isoprenoid residues.
Vitamin K1, also known as, phylloquinone, is synthesized by green
plants.
Vitamin K2 can be classified into several menaquinone forms, vitamin K2
can be synthesized in the large intestine by bacteria. This synthesis
pathway, however, is commonly carried out in germ-free rats, and is
proven to be gut bacteria-independent.

5. Mol. Formula C31H46O2
Presence of quinone group
Vitamin K is a lemon yellow oil which on catalytic hydrogenation
takes 4 moles of hydrogen to yield a colorless octahydro derivative.
Later, that oxidised in air and gives yellow hexahydro compund again.
Presence of 1,4-napthaquinone group
The UV spectra of the Vitamin K1 exhibit adsorption maxima at
243, 249, 260 and 210 nm, which reveals presence of napthaquinone
group.
Oxidation
Vitamin K1 oxidised with chromic acid, it yield phatalic acid
(major) and 2-methyl 1,4-naphthaquinone-3-acetic acid (minor). This
indicates Vitamin K1 has 1,4 naphthaquninone skeleton in which
position 2 is substituted by a methyl group and another substituent is
present 3.

6. Presence of double bond inside chain
If 1,4-naphthaquinone is reduced under the same conditions as
Vitamin K1, it takes up three moles of hydrogen. Therefore , the addition
of a fourth molecule of hydrogen to Vitamin K1 suggests the presence of
an ethynylic double bond in a side chain.

7. Synthesis of Vitamin K1
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