Polymerization, violent

Styrene is mildly toxic, flammable, and can be made to polymerize violently under certain conditions. However, handled according to proper procedures, it is a relatively safe organic chemical. Styrene vapor has an odor threshold of 50—150 ppm (72,73). 

Diketene polymerizes violently in the presence of alkali. Distd at reduced pressure, then fractionally crystd by partial freezing (using as a cooling bath a 1 1 soln of Na2S203 in water, cooled with Dry-ice until slushy, and stored in a Dewar flask). Freezing proceeds slowly, and takes about a day for half completion. The crystals are separated and stored in a refrigerator under N2. See ketene on p. 276. 

Chemical Reactivity - Reactivity with Water No reaction unless in the presence of acids and caustics Reactivity with Common Materials Slow decomposition occurs, but generally the reactions are not hazardous Stability During Transport Stable if cool Neutralizing Agents for Acids and Caustics Not pertinent Polymerization Violent, exothermic polymerization occurs at about 225 of. Acid fumes will also cause polymerization at ordinary temperatures Inhibitor of Polymerization None reported. 

Polymerization,- Violent. Violent monomer polymerization has caused a number of serious explns. Present in Table 1 below is a summary of data pertinent to the causation of these explns, extracted from the ref. The monomers listed may be found under appropriate entry titles thruout the Encycl Ref M. Harmon J. King, A Review of Violent Monomer Polymerization A Selected literature Survey , Report No USCG-D-159-75, Contract DOT-CG-51, 765-A, Operations Research, Inc, Silver Spring (1974)... 

Must be inhibited Colourless, partially water soluble liquid Experimental carcinogen Polymerizes violently with organic peroxides or concentrated caustic alkalis... 

Polymerization of cyclic compounds may also occur by ionic mechanisms under the influence of strong acids or bases and in the absence of water and alcohols. Thus, in the presence of a strong acid or electron acceptor (BF3), ethylene oxide may polymerize violently. The mechanism may be the following, where the electron acceptor is represented by the hydrogen ion ... 

Decomposition 2,4,6-Trichloro-s-Triazine which can polymerize violently. 

Acrylonitrile (Vinyl cyanide, propenenitrile) CH2 CHCN 0 481 3.0-17.0 0.8 1.8 77 Colourless, partially water soluble liquid Experimental carcinogen Polymerizes violently with organic peroxides or concentrated caustic alkalis Highly toxic Usually inhibited... 

Diketene polymerizes violently in the presence of alkali. Distd at reduced pressure, then fractionally crystd by... 

Reactivity. Flammable polymerizes violently in the presence of trace amounts of metals or acids can react violently with acid anhydrides, alcohols, ketones, phenols, ammonia, hydrocyanic acid, hydrogen sulfide, halogens, phosphorus, isocyanates, strong alkalis and amines (American Conference of Governmental Industrial Hygienists, 1991)... 

Vinyl Chloride. See in Vol 3, C255-R to C256-L under Chloroethylene and Derivatives , and Vol 3, P343-R to P345 under Polymerization, Violent . The polymer is to be found in Vol 3, P354-R to P356-L under Polyvinyl Chloride . Addnl Refs on both the monomer (VCM) and the polymer (PVC) are presented next ... 

Compns contg reaction products of vinyli-dene chloride and ozone are also extremely dangerous. See also in Vol 8, P344—45 under Polymerization, Violent , and the preceding entry... 

Acids or Bases. Liable to polymerize violently, especially in contact with strong acidic or basic catalysts. Hydroquinone is added as stabilizer but may lose its effectiveness after a short storage time.3... 

Tends to polymerize violently, so it must never be stored uninhibited, in light or close to bases. 

Silver Nitrate. May polymerize violently in the presence of solid silver nitrate.6... 

Ethylene Oxide. Polymerizes violently in the presence of aluminum chloride.5... 

Reacts violently with many chemicals, including acetic acid, acetic anhydride, acrolein, acrylic acid, allyl chloride, carbon disulfide, chloride glyoxal, and vinyl acetate.4 Acids. Polymerizes violently.5... 

Hydrogen cyanide condenses at 25.6°C to a liquid with a very high dielectric constant (107 at 25°C). Here, as in similar cases, such as water, the high dielectric constant is due to association of intrinsically very polar molecules by hydrogen bonding. Liquid HCN is unstable and can polymerize violently in the absence of stabilizers in aqueous solutions polymerization is induced by ultraviolet light. 

Acrylonitrile will polymerize violently in the absence of oxygen if initiated by heat, light, pressure, peroxide, or strong acids and bases. It is unstable in the presence of bromine, ammonia, amines, and copper or copper alloys. Neat acrylonitrile is generally stabilized against polymerization with trace levels of hydroquinone monomethyl ether and water. 

DOT CLASSIFICATION 6.1 Label Poison SAFETY PROFILE Poison by ingestion, skin contact, subcutaneous, intravenous, and intraperitoneal routes. A severe eye irritant. Combustible when exposed to heat or flame. Polymerizes violently when heated to 130°C or on contact with strong base. May spontaneously explode when stored at 70-80°C. To fight fire, use water, fog, spray, foam. When heated to decomposition it emits toxic fumes of NOx and CN. See also NITRILES. 

Acrolein is highly reactive and is likely to polymerize violently/explosively into dimethylaniline in the presence of strong acids or bases. Care should be taken to prevent mixing with amines, sulfur dioxide, metal salts, and oxidants. In addition, acrolein is sensitive to heat, light, and air unless an inhibitor such as... 

Acrylamide is reactive but stable at room temperature. It can polymerize violently when heated to its melting point (84.5°C) or under ultraviolet light. 

Flammable when exposed to heat or flame. When heated to decomposition or on contact with water or steam, it will react to produce highly toxic and corrosive fumes of hydrogen cyanide, hydrochloric acid, and nitrogen oxides. Contact with alcohols, acids, acid salts, amines, strong alkalis, olefins, and strong oxidizers may cause fire and explosion. Cyanogen chloride may polymerize violently if contaminated with chlorine. 

Difluoroethylene is extremely flammable and explosive. It may polymerize violently under high-temperature conditions or upon contamination with other products. 

Properties Colorless, odorless crystals. Mp 84.5C, bp 125C (25 mm), d 1.122 (30C). Soluble in water, alcohol, acetone insoluble in benzene, heptane. The solid is stable at room temperature but may polymerize violently on melting. 

HCN is not completely stable and is marketed as a stabilized (often with H3PO4), flammable, anhydrous material. It reacts when heated, or in the presence of base or water, and may polymerize violently in contact with strong acids (e.g., sulfuric acid). Polymerization, once initiated, can be autocatalytic and, under confined conditions, lead to an explosion. It can be removed from waste streams by conversion to ammonium thiocyanate, a process involving scmbbing the waste stream with elemental sulfur in water (http //www.chemalliance.org). 

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