2,2-Dimethylbutane Property

Melting point:

−100 °C(lit.)

Boiling point:

50 °C(lit.)

Density 

0.649 g/mL at 25 °C(lit.)

vapor density 

2.97 (vs air)

vapor pressure 

5.35 psi ( 20 °C)

refractive index 

n20/D 1.369(lit.)

Flash point:

<−30 °F

storage temp. 

Flammables area

solubility 

In methanol: 590 and 800 g/L at 5 and 10 °C, respectively. Miscible at higher temperatures (Kiser et al., 1961). Miscible with other aliphatic hydrocarbons, e.g., pentane, hexane, heptane, etc.

pka

>14 (Schwarzenbach et al., 1993)

form 

Liquid

color 

Clear colorless to slightly yellow

Odor Threshold

20ppm

explosive limit

~7.7%

Water Solubility 

insoluble

BRN 

1730736

Henry's Law Constant

1.69(atm?m³/mol) at 25 °C (Mackay and Shiu, 1981)

Dielectric constant

1.8700000000000001

Exposure limits

ACGIH TLV: TWA and STEL for all isomers except n-hexane are 500 and 1,000 ppm, respectively (adopted).

Stability:

Stable, but may be moisture sensitive. Highly flammable. Incompatible with strong oxidizing agents.

CAS DataBase Reference

75-83-2(CAS DataBase Reference)

NIST Chemistry Reference

Butane, 2,2-dimethyl-(75-83-2)

EPA Substance Registry System

2,2-Dimethylbutane (75-83-2)

Safety

Hazard Codes 

F,Xn,N

Risk Statements 

11-38-51/53-65-67

Safety Statements 

9-16-29-33-61-62

RIDADR 

UN 1208 3/PG 2

WGK Germany 

3

RTECS 

EJ9300000

Autoignition Temperature

797 °F

HazardClass 

3

PackingGroup 

II

HS Code 

29011000

Hazardous Substances Data

75-83-2(Hazardous Substances Data)

Toxicity

Reported as an impurity (0.2 wt %) in 99.0–99.7 wt % 2,3-dimethylbutane (Chevron Phillips, 2004).

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Danger

Hazard statements

H225Highly Flammable liquid and vapour

H304May be fatal if swallowed and enters airways

H315Causes skin irritation

H336May cause drowsiness or dizziness

H411Toxic to aquatic life with long lasting effects

Precautionary statements

P210Keep away from heat/sparks/open flames/hot surfaces. — No smoking.

P233Keep container tightly closed.

P273Avoid release to the environment.

P301+P310IF SWALLOWED: Immediately call a POISON CENTER or doctor/physician.

P303+P361+P353IF ON SKIN (or hair): Remove/Take off Immediately all contaminated clothing. Rinse SKIN with water/shower.

P331Do NOT induce vomiting.

2,2-Dimethylbutane Chemical Properties,Usage,Production

Chemical Properties

2,2-dimethylbutane is the chain isomeric form of hexane. It is a colorless and flammable liquid with a specific gravity of 0.6444. Insoluble in water, miscible with alcohol, ether, acetone, benzene and petroleum ether. The solubility is similar to that of hexane and 2-methylpentane.

Physical properties

Clear, colorless liquid with a mild petroleum-like odor. Liquid quickly evaporates and forms conbustible fumes. An odor threshold concentration of 20 ppm_v was reported by Nagata and Takeuchi (1990).

Uses

2,2-Dimethylbutane is an acyclic alkane. Its Research Octane Number (RON) has been reported to be 91.8. It is used to Component of high-octane motor and aviation fuels, intermediate for agricultural chemicals.

Application

2,2-Dimethylbutane may be employed as probe to investigate the nature of possible active sites in supported metal catalysts.
Some of the reported applications of 2,2-dimethylbutane include:
Palladium-catalyzed radical oxidative alkoxycarbonylation to prepare various alkyl carboxylates.
Iridium-iron-catalyzed tandem dehydrogenation-isomerization-hydrosilylation to synthesize corresponding silane.

Preparation

2,2-Dimethylbutane can be synthesised by the hydroisomerisation of 2,3-dimethylbutane using an acid catalyst.
By the thermal or catalytic union (alkylation) of ethylene and isobutane, both recovered from refinery gases.

Production Methods

2,2-Dimethylbutane is produced from crude oil, natural liquid gases, and petroleum refining processes.

General Description

Colorless liquid with an odor of gasoline. Less dense than water and insoluble in water. Hence floats on water. Irritating vapor. Flash point -54°F.

Air & Water Reactions

Highly flammable. Insoluble in water.

Reactivity Profile

2,2-Dimethylbutane may be incompatible with strong oxidizing agents like nitric acid. Charring may occur followed by ignition of unreacted material and other nearby combustibles. In other settings, mostly unreactive. Not affected by aqueous solutions of acids, alkalis, most oxidizing agents, and most reducing agents. When heated sufficiently or when ignited in the presence of air, oxygen or strong oxidizing agents, burns exothermically to produce carbon dioxide and water.

Hazard

Highly flammable, dangerous fire and explosion risk, explosion limits 1.2–7%

Health Hazard

Inhalation causes dizziness, nausea, and vomiting; concentrated vapor may cause unconsciousness and collapse. Contact with liquid causes irritation of eyes; repeated contact may produce irritation of skin. Ingestion causes irritation of stomach. Aspiration causes severe lung irritation, rapidly developing pulmonary edema, and central nervous system excitement followed by depression.

Safety Profile

Probably an irritant and narcotic in high concentration. A very dangerous fire and explosion hazard when exposed to heat or flame; can react vigorously with oxidzing materials. Keep away from heat or open flame. To fight fire, use foam, CO2, dry chemical. When heated to decomposition it emits acrid smoke and irritating fumes.

Environmental Fate

Photolytic. Reported photooxidation rate constants for the reaction of 2,2-dimethylbutane with OH radicals at 297, 299, and 300 K are 2.59 x 10^-12, 6.16 x 10^-12, and 2.59 x 10^-12 cm³/molecule?sec, respectively (Atkinson, 1985, 1990).
Chemical/Physical. Complete combustion in air yields carbon dioxide and water vapor. 2,2- Dimethylbutane will not hydrolyze because it has no hydrolyzable functional group.

Purification Methods

Distil it azeotropically with MeOH, then wash it with water, dry (Na2SO4) it, and distil it. [Beilstein 1 IV 367.]