NIOSH Pocket Guide to Chemical Hazards


CAS 126-99-8


RTECS EI9625000
Synonyms & Trade Names
2-Chloro-1,3-butadiene; Chlorobutadiene; Chloroprene
DOT ID & Guide
1991 131P (inhibited)


NIOSH REL: Ca C 1 ppm (3.6 mg/m3) [15-minute] See Appendix A
OSHA PEL: TWA 25 ppm (90 mg/m3) [skin]
IDLH Ca [300 ppm] See: 126998 Conversion 1 ppm = 3.62 mg/m3
Physical Description
Colorless liquid with a pungent, ether-like odor.
MW: 88.5
BP: 139°F
FRZ: -153°F
Sol: Slight
VP: 188 mmHg
IP: 8.79 eV

Sp.Gr: 0.96
Fl.P: -4°F
UEL: 11.3%
LEL: 1.9%

Class IB Flammable Liquid: Fl.P. below 73F and BP at or above 100F.
Incompatibilities & Reactivities
Peroxides & other oxidizers [Note: Polymerizes at room temperature unless inhibited with antioxidants.]
Measurement Methods
NIOSH 1002; OSHA 112
See: NMAM or OSHA Methods
Personal Protection & Sanitation (See protection)
Skin: Prevent skin contact
Eyes: Prevent eye contact
Wash skin: When contaminated
Remove: When wet (flammable)
Change: No recommendation
Provide: Eyewash, Quick drench
First Aid (See procedures)
Eye: Irrigate immediately
Skin: Soap wash immediately
Breathing: Respiratory support
Swallow: Medical attention immediately
Important additional information about respirator selection
Respirator Recommendations NIOSH
At concentrations above the NIOSH REL, or where there is no REL, at any detectable concentration:
(APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode
(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus
(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, skin absorption, ingestion, skin and/or eye contact
Symptoms Irritation eyes, skin, respiratory system; anxiety, irritability; dermatitis; alopecia; reproductive effects; [potential occupational carcinogen]
Target Organs Eyes, skin, respiratory system, reproductive system

Cancer Site [lung & skin cancer]
See also: INTRODUCTION   See ICSC CARD: 0133   See MEDICAL TESTS: 0050