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Substance Name: Guanidine
RN: 113-00-8


  • A strong organic base existing primarily as guanidium ions at physiological pH. It is found in the urine as a normal product of protein metabolism. It is also used in laboratory research as a protein denaturant. (From Martindale, the Extra Pharmacopoeia, 30th ed and Merck Index, 12th ed) It is also used in the treatment of myasthenia and as a fluorescent probe in HPLC.

Molecular Formula

  • C-H5-N3

Molecular Weight

  • 59.0715

Classification Code

  • Natural Product
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Names and Synonyms

Name of Substance

  • Guanidine

MeSH Heading

  • Guanidine


  • 4-03-00-00148 (Beilstein Handbook Reference)
  • Aminoformamidine
  • Aminomethanamidine
  • BRN 0506044
  • Carbamamidine
  • Carbamidine
  • EINECS 204-021-8
  • Guanidine
  • HSDB 7603
  • Imidourea
  • Iminourea

Systematic Name

  • Guanidine

Registry Numbers

CAS Registry Number

  • 113-00-8


  • JU58VJ6Y3B

Related Registry Numbers

  • 1184-68-5 (unspecified sulfate)
  • 1763-07-1 (unspecified phosphate)
  • 19244-98-5 (mono-hydrobromide)
  • 50-01-1 (mono-hydrochloride)
  • 52470-25-4 (nitrate)
  • 594-14-9 (sulfate 2:1)
  • 64120-25-8 (monohydrate)
  • 646-34-4 (sulfate 1:1)

System Generated Number

  • 0000113008

Structure Descriptors








Organism Test Type Route Reported Dose (Normalized Dose) Effect Source
frog LDLo subcutaneous 3gm/kg (3000mg/kg)   "Abdernalden's Handbuch der Biologischen Arbeitsmethoden." Vol. 4, Pg. 1352, 1935.
mouse LD50 intraperitoneal 350mg/kg (350mg/kg)   Bulletin of Experimental Biology and Medicine Vol. 61, Pg. 291, 1966.
mouse LDLo subcutaneous 266mg/kg (266mg/kg)   "Abdernalden's Handbuch der Biologischen Arbeitsmethoden." Vol. 4, Pg. 1352, 1935.
rabbit LDLo oral 500mg/kg (500mg/kg)   "Merck Index; an Encyclopedia of Chemicals, Drugs, and Biologicals", 11th ed., Rahway, NJ 07065, Merck & Co., Inc. 1989Vol. 11, Pg. 718, 1989.
rat LDLo subcutaneous 150mg/kg (150mg/kg)   "Abdernalden's Handbuch der Biologischen Arbeitsmethoden." Vol. 4, Pg. 1352, 1935.

Physical Properties

Physical Property Value Units Temp (deg C) Source
Melting Point 50 deg C   EXP
log P (octanol-water) -1.630 (none)   EST
Water Solubility 1840 mg/L 20 EXP
Vapor Pressure 4.100 mm Hg 25 EST
Henry's Law Constant 2.34E-11 atm-m3/mole 25 EST
Atmospheric OH Rate Constant 4.20E-11 cm3/molecule-sec 25 EST

Physical property data is provided to ChemIDplus by SRC, Inc.