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Vitamin K6.svg
Preferred IUPAC name
3D model (JSmol)
  • InChI=1S/C11H12N2/c1-7-6-10(12)8-4-2-3-5-9(8)11(7)13/h2-6H,12-13H2,1H3
  • CC1=C(C2=CC=CC=C2C(=C1)N)N
Molar mass 172.231 g·mol−1
Appearance yellowish crystals[1]
Melting point 110-113 °C[3][1]
dihydrochloride is freely soluble[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

2-Methylnaphthalene-1,4-diamine is a synthetic menadione analog with vitamin K activity.[3][2]

2-Methylnaphthalene-1,4-diamine was first synthesized in 1925.[1][3] In 1942 two different research groups noted the vitamin K activity of the compound.[3][4][5] It forms a dihydrochloride salt (C11H14Cl2N2) with hydrochloric acid and one of the aforementioned research groups suggested the name vitamin K6 for the salt.[3]

2-Methylnaphthalene-1,4-diamine and its dihydrochloride can be made from 2-methylnaphthalene or its close analogs. Dihydrochloride blackens without melting at about 300 °C.[3]

4-Amino-3-methyl-1-naphthol or its dihydrochloride have not been used as commercial medicinal forms of vitamin K unlike phylloquinone and menadione for example.[6]

Oral toxicity of dihydrochloride for rats is approximately the same as for 4-amino-2-methyl-1-naphthol hydrochloride.[3]


  1. ^ a b c Veselý V, Kapp J (1925). "Sur les dérivés nitres du méthyl-2-naphtalène". Recueil des Travaux Chimiques des Pays-Bas. 44 (4): 360–375. doi:10.1002/recl.19250440409. ISSN 0165-0513.
  2. ^ a b Budavari S, et al. (2000). The Merck index (12th ed.). Chapman & Hall Electronic Pub. Division. p. 1581. ISBN 9781584881292.
  3. ^ a b c d e f g Veldstra H, Wiardi PW (1943). "Water soluble antihemorrhagic substances I: synthesis of 2-methyl-4-aminonaphthol-1 hydrochloride and of 2-methyl-1,4-diaminonaphthalene dihydrochloride, the water soluble synthetic vitamins K5 and K6". Recueil des Travaux Chimiques des Pays-Bas. 62 (2): 75–84. doi:10.1002/recl.19430620203. ISSN 0165-0513.
  4. ^ Baker BR, Carlson GH (1942). "Water-soluble compounds with antihemorrhagic activity". Journal of the American Chemical Society. 64 (11): 2657–2664. doi:10.1021/ja01263a038. ISSN 0002-7863.
  5. ^ Robinson FA, Holland DO (1948). "Preparation of water-soluble derivatives of 2-methylnaphthalene". Journal of the Chemical Society. 2: 182–186. doi:10.1039/JR9480000182. ISSN 0368-1769. PMID 18906382.
  6. ^ Fiore LD, et al. (2001). "Anaphylactoid reactions to vitamin K". Journal of Thrombosis and Thrombolysis. 11 (2): 175–183. doi:10.1023/A:1011237019082. ISSN 1573-742X. PMID 11406734. S2CID 975055.