Hazardous reactions with aluminium

Phosgene reacts, sometimes violently, with a large number of common inorganic (Chapter 9) and organic (Chapter 10) substances. Hazardous reactions with lithium, sodium, potassium, aluminium, lithium amide, hexa-2,4-diyn-l, 6-diol, propan-2-ol, and hexafluoropropene have been mentioned specifically [1787]. Mixtures of potassium and phosgene are reported to explode when subjected to shock [1913a]. In addition, phosgene... 

It is the formation of this material which makes the reaction have a low atom economy and, owing to the cost of disposal (usually by conversion to calcium phosphate and disposal as hazardous waste), has limited its commercial usefulness to high value products. Several methods have been developed to recycle (Ph)3PO into (Ph)3P but these have proved more complex than might be expected. Typically the oxide is converted to the chloride which is reduced by heating with aluminium. Overall this recovery is expensive and also produces significant amounts of waste. 

Electrophilic Substitution Reactions of Monocyclic Thiophens. -The hazards connected with the use of chloromethyl and dichloro-methyl ether have attracted interest in alternative reagents for the chloromethylation of aromatics. A convenient reagent appears to be methoxyacetyl chloride and aluminium chloride in nitromethane... 

Dangerous materials may require special equipment. Chlorination with gaseous chlorine requires quite expensive storage facilities. Chlorination with chlorine, thionyl chloride, sulphuryl chloride, phosphorus oxychloride, phosphorus trichloride, or phosphorus pentachloride, all of which are fairly hazardous, requires off-gas treatment. Some of these reactants can be recycled. Pyrophoric solids such as hydrogenation catalysts, anhydrous aluminium trichloride for Friedel-Crafts reactions, or hydrides used as reducing agents should usually be handled using special facilities. Therefore, all of the above proce.sses are usually carried out in dedicated plants. 

A joint between a mild steel valve screwed onto an aluminium pipe was leaking a resin-solvent mixture, and when the joint was tightened with a wrench, a flash fire occurred. This was attributed to generation of sparks by a thermite reaction between the rusted steel valve and the aluminium pipe when the joint was tightened [1]. Hazards involved in the use of aluminium-sprayed steel are reviewed [2],... 

---