The Contribution of cocoa additive to cigarette smoking addiction

RIVM report 650270002 Page 9 of 207
Theobromine
3. Results
3.1 Theobromine
GENERAL
IUPAC systematic name: 3,7-dihydro-3,7-dimethyl-1H-purine-2,6-dione (1, 2)
Synonyms: 3,7-dimethylxanthine, diurobromine, santheose, SC 15090, theosalvose,
theostene, thesal, thesodate (1, 2)
Molecular formula: C7H8N4O2 (3)
Molecular structure
N
N
H3C CH 3
N O
O
NH
Molecular weight: 180.17 (2-4), 180.19 (1)
Alifatic: no
Aromatic: yes
N containing:yes
Halogen containing: no
CAS registry no.: 83-67-0 (3)
Storage:
R/S classification: no data available.
dangercode (transport): no data available.
Properties:
melting point: 357 °C (3, 4)
boiling point: 290 –295 °C (sublimes) (2, 3)
density: no data available.
refractive index: no data available.
solubility: H2O, ethanol (3, 4), ether (3), moderately in ammonia, slightly soluble
in chloroform (4), almost insoluble in benzene, (diethyl)ether, carbon tetrachloride
(1, 2, 4)
substance description:
white (1)
powder or monoclinic needles (1, 2)
bitter taste (1)
volatility: no data available.
pKa: 7.89 (18 °C) (3)
Kb = 1.3 x 10 -14 (18 °C) (2, 4)
Ka = 0.9 x 10 -10 (2, 4)
NB: The pKa-value of ref (3) is not in accordance with the K a -value given by refs. (2, 4). Refs (2, 4)
mention both a K a- and a K b-value, indicating that theobromine can act both as a proton acceptor (a
base) as well as a proton donor (an acid). Ref (3) only indicates a pK a-value: most probably this value
reflects a netto result in water of both the acid and base properties.
PA: no data available.