Title: Pyrithyldione
CAS Registry Number: 77-04-3
CAS Name: 3,3-Diethyl-2,4-(1H,3H)pyridinedione
Additional Names: 3,3-diethyl-2,4-dioxotetrahydropyridine; 2,4-dioxo-3,3-diethyltetrahydropyridine; 2,4-dioxo-3,3-diethyl-1,2,3,4-tetrahydropyridine
Trademarks: Presidon; Persedon (Roche); Tetridin; Benedorm
Molecular Formula: C9H13NO2
Molecular Weight: 167.21
Percent Composition: C 64.65%, H 7.84%, N 8.38%, O 19.14%
Literature References: Prepn: Schnider, Festschr. Emil Barell 1936, 195; Preiswerk, Schnider, US 2090068 (1937 to Hoffmann-La Roche); Strukov et al., Med. Prom. SSSR 13, no. 9, 9 (1959). Alternate procedure: Rechen et al., US 3019230 (1962 to Hoffmann-La Roche).
Properties: Exists in three cryst modifications: I, mp 92-93°; II, mp 97-98°; III, mp 81-86° [Scheibl, Wachter, Arch. Toxikol. 18, 253 (1960)]. bp14 187-189°. Moderately sol in water; freely sol in the usual organic solvents except petr solvents. Aq solns are just acid to litmus.
Melting point: mp 92-93°; mp 97-98°; mp 81-86° [Scheibl, Wachter, Arch. Toxikol. 18, 253 (1960)]
Boiling point: bp14 187-189°
Therap-Cat: Sedative, hypnotic.
Keywords: Sedative/Hypnotic; Piperidinediones.
Pyrocalciferol Pyrocarbonic Acid Diethyl Ester Pyrocatechol Pyrogallol Pyrolan

Pyrithyldione ball-and-stick.png
Systematic (IUPAC) name
Clinical data
Trade names Benedorm, Didropyridine, Dihydroprylone, Persedon, Presidon, Pyridion, Pyridione, Pyrithyldion, Pyrithyldione, Tetridin, Tetridine
Legal status  ?
CAS number 77-04-3 N
ATC code N05CE03
PubChem CID 4994
ChemSpider 4820 YesY
UNII 8AB20823CK YesY
KEGG D07329 YesY
Chemical data
Formula C9H13NO2 
Mol. mass 167.205 g/mol
 N (what is this?)  (verify)

Pyrithyldione (Presidon, Persedon) is a psychoactive drug invented in 1949.[1] An improved method of manufacture was patented by Roche in 1959.[2] It was used as a hypnotic or sedative and presumed to be less toxic than barbiturates.[3] Today, this substance is no longer used. Agranulocytosis was sometimes reported as adverse effect.[4][5]