Molecular Structure of 5-(2-Ethoxyphenyl)-1-methyl-3-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]-7-pyrimidinone (CAS NO.139756-21-1):

Systematic Name: 5-(2-Ethoxyphenyl)-1-methyl-3-propyl-1,4-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one 
Molecular Formula: C₁₇H₂₀N₄O₂
Molecular Weight: 312.37
Melting Point: 141-145 °C(lit.)
Index of Refraction: 1.632
Molar Refractivity: 88.04 cm³
Molar Volume: 246.8 cm³
Surface Tension: 45.7 dyne/cm
Density: 1.26 g/cm³
Flash Point: 258.6 °C
Enthalpy of Vaporization: 77.34 kJ/mol
Boiling Point: 504 °C at 760 mmHg
Vapour Pressure: 2.75E-10 mmHg at 25 °C
Appearance: Light-Yellow Solid
SMILES: O=C2/N=C(\Nc1c(nn(c12)C)CCC)c3ccccc3OCC
InChI: InChI=1/C17H20N4O2/c1-4-8-12-14-15(21(3)20-12)17(22)19-16(18-14)11-9-6-7-10-13(11)23-5-2/h6-7,9-10H,4-5,8H2,1-3H3,(H,18,19,22)
InChIKey: MXQUEDUMKWBYHI-UHFFFAOYAL 
Product Categories: Heterocyclic Compounds; Nucleotides and Nucleosides; Bases & Related Reagents; Intermediates; Nucleotides; Building Blocks; Heterocyclic Building Blocks; Pyrimidines

 5-(2-Ethoxyphenyl)-1-methyl-3-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]-7-pyrimidinone (CAS NO.139756-21-1) is used as sildenafil impurity.

Safety Information of 5-(2-Ethoxyphenyl)-1-methyl-3-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]-7-pyrimidinone (CAS NO.139756-21-1):
Hazard Codes: Xi
Risk Statements: 36/37/38 
R36/37/38:Irritating to eyes, respiratory system and skin.
Safety Statements: 26-36 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S36:Wear suitable protective clothing.
WGK Germany: 3

 5-(2-Ethoxyphenyl)-1-methyl-3-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]-7-pyrimidinone (CAS NO.139756-21-1), its Synonyms are 7H-Pyrazolo[4,3-d]pyrimidin-7-one,5-(2-ethoxyphenyl)-1,6-dihydro-1-methyl-3-propyl- ; 7H-Pyrazolo[4,3-d]pyrimidin-7-one,5-(2-ethoxyphenyl)-1,4-dihydro-1-methyl-3-propyl- (9CI) ; 5-(2-Ethoxyphenyl)-1-methyl-3-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one .