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A0279656

AcetateBuffer , PH6.0

Synonym(s):
2-Methyl-1,3-butadiene;Isoprene

CAS NO.:

Empirical Formula: C5H8

Molecular Weight: 68.12

MDL number: MFCD00008600

EINECS: 201-143-3

Update time: 2022-07-08

PRODUCT Properties

Melting point: 323-329 °C(lit.)
Boiling point: 34 °C(lit.)
Density  0.681 g/mL at 25 °C(lit.)
vapor density  2.35 (vs air)
vapor pressure  8.82 psi ( 20 °C)
refractive index  n20/D 1.422(lit.)
Flash point: −65 °F
storage temp.  Store at <= 20°C.
solubility  0.7g/l
form  solid
pka >14 (Schwarzenbach et al., 1993)
color  Clear colorless to very pale yellow
Odor petroleum-like odor
explosive limit 1-9.7%(V)
Odor Threshold 0.048ppm
Water Solubility  0.07 g/100 mL
FreezingPoint  -145.96℃
λmax 231nm(neat)(lit.)
Merck  14,5201
BRN  969158
Henry's Law Constant (x 10-2 atm?m3/mol): 3.45 at 18 °C (dynamic stripping cell-MS, Karl et al., 2003)
Dielectric constant 2.1(25℃)
Stability: Stability Extremely flammable. Readily forms explosive mixtures with air. Note low flash point, low boiling point, high vapour pressure. Unstable - prone to spontaneous polymerization. May contain a polymerization inhibitor. Incompatible with strong oxidizing agents.
LogP 2.42 at 20℃

Description and Uses

Isoprene is a naturally occurring clear colorless volatile liquid (at room temperature) with a faint odor. Isoprene is an important building block for lipids, steroids, terpenoids, and a wide variety of natural products, including natural rubber. Isoprene is found in abundance in nature and is produced and emitted to the environment by plants and trees; it is also emitted from food crops since isoprene serves as the basic structural unit of numerous substances such as terpenes and vitamins A and K. Hence, isoprene is found in ambient air at low concentrations (e.g., the reported concentration of isoprene in the ambient air of the United States ranges between 1 and 21 ppb and is generally less than 10 ppb). Because the biosynthesis of isoprene is associated with photosynthesis, emission of isoprene from plants and trees is negligible at night. Emission of isoprene from plants and trees is also seasonal with the highest emission occurring in the summer and the lowest emission occurring in the winter. Once emitted to the atmosphere, isoprene is converted by free radicals (e.g., nitric oxide, hydroxyl radicals, ozone) to various species (e.g., aldehydes, hydroperoxides, organic nitrates, epoxides) that mix with water droplets and help create aerosols and haze.
Isoprene is produced endogenously in experimental animals and humans. The rate of endogenous production of isoprene in rats and mice is approximately 1.9 and 0.4 mmol kg-1 h-1, respectively, while in humans it is approximately 0.15 mmol kg-1 h-1 (approximately 2–4 μmol kg-1 per day). The precursor to endogenous isoprene production in humans is believed to be mevalonic acid, a precursor of cholesterol synthesis. Isoprene is the major hydrocarbon found in human breath, accounting for up to 70% of exhaled hydrocarbons. The mean concentration of isoprene reported in human breath is 118 ppb (range 0–474 ppb). The concentration of isoprene in human blood is between 1 and 4.8 μg l-1. The rate of production of isoprene is higher in males than females and in adults than in children.
Anthropogenic sources of isoprene include production of ethylene by cracking naphtha, wood pulping, combustion of wood and other biomass, tobacco smoke (smoking one cigarette can increase the concentration of isoprene in exhaled air by 70%), gasoline, and automobile exhaust.

The majority of isoprene produced commercially is used to make synthetic rubber (cis-polyisoprene), most of which is used to produce vehicle tires. The second- and third-largest uses are in the production of styrene-isoprene-styrene block polymers and butyl rubber (isobutene-isoprene copolymer) (IARC 1994).

Safety

Symbol(GHS) 
GHS02,GHS08
Signal word  Danger
Hazard statements  H224-H341-H350-H412
Precautionary statements  P202-P210-P233-P273-P308+P313-P403+P233
Hazard Codes  F+,T,N
Risk Statements  45-12-52/53-68-51/53
Safety Statements  53-45-61-36/37-16
RIDADR  UN 1218 3/PG 1
WGK Germany  1
RTECS  NT4037000
Autoignition Temperature 428 °F
TSCA  Yes
HS Code  2901 24 00
HazardClass  3
PackingGroup  I
Toxicity LD50 for mice: 144 mg isoprene vapors/l air (Gostinskii)

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