What Is Neoprene Rubber?
Chloroprene is a colorless, volatile liquid with a special pungent odor at room temperature. It is slightly soluble in water and easily soluble in organic solvents such as ethanol, ether, benzene and chloroform. It is an important organic chemical used as an intermediate in organic synthesis and as a monomer for neoprene.
Chinese alias | Chloroprene |
CAS number | 126-99-8 |
Molecular formula | C 4 H 5 Cl; CH 2 CHCClCH 2 |
Molecular weight | 88.54 |
density | Relative density (water = 1) 0.96; |
Water-melt | Slightly soluble in water, soluble in most organic solvents such as ethanol and ether |
use | Important organic chemicals, used as intermediates in organic synthesis, monomers for neoprene, etc. |
Dangerous Goods Sign | 7 (low flash point flammable liquid), 40 (with drugs) |
[2]
Flammable liquids
High toxicity
Acute toxicity oral-rat LD50: 450 mg / kg; oral-mouse LD50: 146 mg / kg
Explosive hazardous properties can be explosive when mixed with air
Flammability and hazardous characteristics Flammable when exposed to open flame, high temperature, oxidant; Decomposes toxic hydrogen chloride gas in case of heat
Storage and transportation characteristicsThe warehouse is ventilated and low-temperature dry; stored separately from oxidants and acids; not stored for a long time to prevent polymerization
Fire extinguishing agent dry powder, dry sand, carbon dioxide, foam, 1211 fire extinguishing agent
Occupational standard TWA 35 mg / m 3 ; STEL 3.6 mg / m 3 [3]
Dangerous goods mark F, T
Danger category code 10-20 / 22-36-48 / 20-36 / 37 / 38-11-45-39 / 23/24 / 25-23 / 24/25
Safety instructions 16-45-53-36 / 37-7
Dangerous Goods Transport Number 1993
HazardClass 3.1
PackingGroup I [3]
Monomer for making neoprene. [2]
Chemical formula: CH2 = CCl-CH = CH2
Molecular weight: 88.54 (1ppm = 2.62mg / m3)
Properties: Colorless, volatile liquid with special pungent odor at room temperature
Boiling point: 59.4 ° C (at 101KPa)
Melting point: -130 ° C
Relative density: (water = 1): 0.96
Vapor pressure: 20KPa at 26.7 ° C; relative vapour density (air = 1) 3.06
Volatile: volatile
Solubility: slightly soluble in water, easily soluble in organic solvents such as ethanol, ether, benzene, chloroform
Flash point: -22 ° C
Auto-ignition temperature: 320
Explosion limit: 2.1% 11.5% (full product) in air
Oil-water partition coefficient: logarithm of octanol / water partition coefficient: 2.1
Health hazard
Invasion: inhalation, ingestion, percutaneous absorption.
Health hazards: Central nervous system inhibition and respiratory tract irritation.
Acute poisoning: tearing, dry throat pain, chest tightness, dyspnea, short-term inhalation of high-concentration vapors; congestion of the conjunctiva and pharynx; scattered lungs; and dizziness, headache, fatigue, numbness of limbs, unstable gait, nausea , Vomiting, coma, convulsions, etc. A few cases of acute pulmonary edema and death. Liver and kidney damage and hair loss can occur after the acute phase. [2]
Gas detection tube method
Gas rapid test tube (product of Dräger, Germany)
Gas Chromatography "Analytical Method for Monitoring and Analysis of Air and Exhaust Gas", compiled by the State Environmental Protection Agency
| China (TJ36-79) | Maximum allowable concentration in workshop air | 2mg / m (skin) |
| China (TJ36-79) | Maximum allowable concentration in the atmosphere of a residential area | 0.1mg / m (primary value) |
| Former Soviet Union (1975) | Maximum allowable concentration of harmful organic matter in water | 0.1mg / L |
| Former Soviet Union (1975) | Maximum allowable concentration of organic matter in sewage | 10mg / L |
| Olfactory threshold concentration | 0.11ppm |
Vapor mixed with air has the danger of burning and exploding; contact with strong oxidants can cause combustion; vapour can diffuse to a distance, and reignite when exposed to open flames; inhalation of high concentrations of this product vapor can cause poisoning and even death. Initially there are irritation symptoms, and gradually appear the nervous system damage.
H2C = CClCH = CH2 Industry is mainly 2-chloro-1,3-butadiene. It is a colorless, volatile, toxic liquid with a spicy odor. by
The warehouse should be ventilated and dry at low temperature; stored separately from oxidants and acids; not stored for a long time to prevent polymerization.
Stored in jacketed cooling equipment, or packed in copper-free steel bottles, and added polymerization inhibitor. Store at low temperature. Store and transport according to the regulations of flammable and toxic chemicals. [4]
In 1931, DuPont of the United States first realized the industrial production of chloroprene from calcium carbide acetylene. Before the 1960s, this was the only way to produce chloroprene industrially. Acetylene generates vinyl acetylene in an acidic aqueous solution of cuprous chloride at 80 ° C, and the latter is further reacted with hydrogen chloride in a solution of cuprous chloride in hydrochloric acid to produce chloroprene: CHtriCH + CHtriCH CH2 = CHC Three CH
CH2 = CHC CH + HCl CH2 = CClCH = CH2
This method has a long history, mature technology, but high cost, and acetylene and vinyl acetylene are easily explosive, and production safety is poor.
Since the 1960s, since the price of acetylene is higher than that of butadiene, the latter has been turned to raw materials. In 1966, the Bitaclo plant in France built the first chloroprene plant from chlorination of butadiene. The gas phase addition of butadiene and chlorine gas at 300 ° C, the product 3,4-dichloro-1-butene (40%) is dehydrochlorinated in a heated alkaline solution to produce chloroprene: CH2 = CHCH = CH2 + Cl2 ClH2CCH = CHCH2 + CH2 = CHCHClCH2Cl
CH2 = CHCHClCH2Cl + NaOH CH2 = CClCH = CH2 + H2O + NaCl
In the process of dehydrochlorination and refining, a small amount of oxygen should be excluded to prevent automatic oxidation, and a polymerization inhibitor chlorination needs to be added. The cis and trans 1,4-dichloro-2-butene (60%) formed at the same time in the reaction can be used as raw materials for the synthesis of adiponitrile and butanediol. Isomerized to 3,4-dichloro-1-butene in the presence of cuprous chloride, which is then used to make chloroprene. The method has low cost, high product quality and good production safety.
