Tetramethylsuccinonitrile

Tetramethylsuccinonitrile or TMSN is an organic compound with the formula (C(CH₃)₂CN)₂, classified as a dinitrile, and a colorless and odorless solid derived from 2,2'-azobis-isobutyronitrile, a common radical initiator in the manufacture of PVC:

[(CH₃)₂C(CN)]₂N₂ → [(CH₃)₂C(CN)]₂ + N₂.^[6]

Quick facts Names, Identifiers ...

Tetramethylsuccinonitrile^[1]

Names
Preferred IUPAC name Tetramethylbutanedinitrile
Other names Butanedinitrile, 2,2,3,3-tetramethyl [2]
Identifiers
CAS Number	3333-52-6 N
3D model (JSmol)	Interactive image
Abbreviations	TMSN[3]
ChemSpider	17700 Y
ECHA InfoCard	100.129.378
MeSH	tetramethylsuccinonitrile
PubChem CID	18745
UNII	116XMU2GHK Y
CompTox Dashboard (EPA)	DTXSID0026125
InChI InChI=1S/C8H12N2/c1-7(2,5-9)8(3,4)6-10/h1-4H3 Y Key: ZVQXQPNJHRNGID-UHFFFAOYSA-N Y
SMILES CC(C)(C#N)C(C)(C)C#N
Properties
Chemical formula	C8H12N2
Molar mass	136.198 g·mol−1
Appearance	Colourless crystals
Odor	odorless[4]
Density	1.07 g mL−1
Melting point	169.1 °C; 336.3 °F; 442.2 K
Boiling point	sublimes[4]
Thermochemistry
Std enthalpy of formation (ΔfH⦵298)	13.6–16.2 kJ mol−1
Std enthalpy of combustion (ΔcH⦵298)	−4.8767–−4.8793 MJ mol−1
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H300, H310, H315, H319, H330, H370, H372, H412
Precautionary statements	P260, P262, P264, P270, P271, P273, P280, P284, P301+P310, P302+P350, P302+P352, P304+P340, P305+P351+P338, P307+P311, P310, P314, P320, P321, P330, P332+P313, P337+P313, P361, P362, P363, P403+P233, P405, P501
Lethal dose or concentration (LD, LC):
LD50 (median dose)	38.9 mg/kg (rat, oral)[5]
LCLo (lowest published)	28 ppm (mouse, 3 hr) 6 ppm (rat, 30 hr)[5]
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 3 mg/m3 (0.5 ppm) [skin][4]
REL (Recommended)	TWA 3 mg/m3 (0.5 ppm) [skin][4]
IDLH (Immediate danger)	5 ppm[4]
Safety data sheet (SDS)	ICSC 1121
Related compounds
Related alkanenitriles	Propanenitrile Aminopropionitrile Malononitrile Pivalonitrile Acetone cyanohydrin Butyronitrile Succinonitrile Glutaronitrile
Related compounds	DBNPA
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

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Because PVC is pervasive and can contain TMSN, the safety aspects of this dinitrile has generated interest.^[7]

In regards to occupational exposures, the U.S. Occupational Safety and Health Administration and the U.S. National Institute for Occupational Safety and Health have set limits for dermal exposure at 3 mg/m³ over an eight-hour time-weighted average.^[3]