High Purity Isobutylene (HPIB)

Benefits and Applications

HPIB is used in the production of alkylated phenols used as antioxidants, lube oil additives, butyl rubber and resins.

Toxicology/Regulatory

The acute toxicity of isobutylene is low, but very high concentrations may cause central nervous system depression, asphyxia, and possibly cardiac sensitization. There is no evidence to suggest that isobutylene is a skin or eye irritant, but evaporating liquid may cause frost injuries. Isobutylene produces dose-responsive increases in the incidence and/or severity of nasal lesions in rats and mice following repeated long-term exposure to high concentrations. These lesions are considered to be non-adverse adaptive responses to prolonged inhalation of irritant material. No signs of developmental toxicity were observed in a screening inhalation test of rats exposed to high concentrations. No biologically significant effects on male or female reproductive organs and parameters were observed in repeated dose inhalation studies with rats and mice at high concentrations.

Isobutylene is not genotoxic in tests conducted in vitro and in vivo at high concentrations. Isobutylene is metabolized in the body to 2-methyl-1,2-epoxypropane, a substance shown to be genotoxic in some in vitro tests; however, this conversion is of doubtful toxicologic significance, given isobutylene's lack of demonstrated genotoxicity. Isobutylene produced an increase in follicular cell carcinomas of the thyroid in male rats following inhalation exposures to 8,000 ppm for two years. Thyroid tumors did not occur in male rats exposed to lower doses, female rats, or male or female mice.

Regulatory Status

X = All components are included or are otherwise exempt from inclusion on this inventory.

If identified components of this product are listed under the TSCA 12(b) Export Notification rule, they will be listed below.

SARA 302/304
No chemicals in this material with known CAS numbers are subject to the reporting requirements of CERCLA.

SARA 311/312
Based on available information, this material is classified as presenting the following health and/or physical hazards, according to Sections 311 and 312: Immediate/Health Fire Hazard Sudden Release of Pressure

SARA 313
This material does not contain any chemical components with known CAS numbers that exceed the De Minimis reporting levels established by SARA Title III, Section 313 and 40 CFR 372.

Storage and Handling

Store away from heat, sparks, open flame, foreign contamination and reducing agents (combustibles). Store so that fire extinguishing media can be applied to all containers from a safe distance or protected location. Store between 50-100°F (10-38°C).

For industrial use only. Closed containers may generate internal gas pressure by decomposition (oxygen), which can accelerate burning of combustibles. Overpressure may rupture container and cause serious injury or result in or accelerate fire. Provide a nitrogen pad to dilute any free oxygen build-up and prevent any hydroperoxide self-combustion. Use only non-sparking tools. Properly ground containers before beginning transfer. All equipment must conform to the applicable electrical code. Minimize formation of sprays during transfer. Inspect frequently to identify bulging or leaking containers. Isolate and depressurize if safe to do so. Do not steam purge systems containing this material until they have been properly flushed with a suitable material, such as mineral oil, kerosene, tertiary butyl alcohol, etc., depending on system compatibility. Isolate, vent, drain, wash, and purge systems or equipment before maintenance or repair. Extinguish all ignition sources. Check the atmosphere for explosiveness and oxygen deficiencies. Wear recommended personal protective equipment. Observe precautions pertaining to confined space entry.