Safety sodium hydride

Use of sodium hydride in DMF to prepare the pyridine acid 3 Safety concerns with use of sodium hydride, and a low yield of acid... 

Although the synthesis of acid 3 developed by our Medicinal Chemistry colleagues proceeded in a single step from commercial starting materials the yield was modest, and there were significant safety concerns about the use of sodium hydride in DMF on a larger scale. After some experimentation it was found that use of the ester in conjunction with just 1 equiv of KHMDS as base gave a clean... 

Employment of sodium hydride in a large scale process would present safety issues, so the choice of base was addressed and tert-butoxide bases were identified... 

For most phase-transfer catalysed reactions, the rate-determining step is the interaction of the reactive substrate with the anionic species in the organic phase and, compared with the corresponding interfacial reaction in the absence of the catalyst, rate enhancements of 107 are not uncommon. The virtual absence of water from the organic phase under strongly basic liquiddiquid or soliddiquid two-phase conditions allows for the formation of water-sensitive anions, such as carbanions (Chapter 6), and obviates the need for strictly anhydrous conditions and the use of bases such as sodium hydride or sodamide, etc. The phase-transfer catalytic process consequently has lower safety risks and is environmentally more friendly. 

SAFETY PROFILE Mildly toxic by ingestion. A skin and eye irritant. Combustible liquid. Reaction with ethyl trifluoroacetate + sodium hydride may cause a fire or explosion. When heated to decomposition it emits acrid smoke and irritating fiimes. See also ESTERS. 

The synthesis had a series of disadvantages, like a poor regioselectivity in the Friedel-Crafts acylation, in which the 1-isomer is also produced, accompanied by educts and by-products with safety-critical properties (nitrobenzene, sodium hydride, methyl iodide, sulfide salts) and an undesirable waste disposal problem, demanding a different synthetic path for the larger production scale. 

LABORATORY CHEMICAL SAFETY SUMMARY POTASSIUM HYDRIDE AND SODIUM HYDRIDE ... 

Sodium aluminate, 2 345t, 358-359 analysis, 2 275-276 economic aspects, 2 275 health and safety factors, 2 276 manufacture, 2 274-275 neutralization, 2 424 physical and chemical properties of, 2 273-274 uses of, 2 276-277 in water treatment, 26 111 Sodium aluminosilicate gels, synthetic zeolites prepared from, 16 831t Sodium aluminosilicates, 12 578 Sodium aluminum hydride, 13 621, 623-624... 

The collected papers of a symposium at Dallas, April 1956, cover all aspects of the handling, use and hazards of lithium, sodium, potassium, their alloys, oxides and hydrides, in 19 chapters [1], Interaction of all 5 alkali metals with water under various circumstances has been discussed comparatively [2], In a monograph covering properties, preparation, handling and applications of the enhanced reactivity of metals dispersed finely in hydrocarbon diluents, the hazardous nature of potassium dispersions, and especially of rubidium and caesium dispersions is stressed [3], Alkaline-earth metal dispersions are of relatively low hazard. Safety practices for small-scale storage, handling, heating and reactions of lithium potassium and sodium with water are reviewed [4],... 

Numerous other types of cells exist such as zinc-air, aluminum-air, sodium sulfur, and nickel-metal hydride (NiMH). Companies are on a continual quest to develop cells for better batteries for a wide range of applications. Each battery must be evaluated with respect to its intended use and such factors as size, cost, safety, shelf-life, charging characteristics, and voltage. As the twenty-first century unfolds, cells seem to be playing an ever-increasing role in society. Much of this is due to advances in the consumer electronics and the computer industry, but there have also been demands in numerous other areas. These include battery-powered tools, remote data collection, transportation (electric vehicles), and medicine. 

Z. Peroxide-free tetrahydrofuran (for precautions, see Org. Synth., Collect. Vol. v 1973, 976) was refluxed over potassium hydroxide pellets for 2 hr, distilled, and dried by addition of ca. 1 g of lithium aluminum hydride prior to use. Failure to heed the precautions can reeutt in a eerioue explosion Drying the THF over sodium-benzophenone is generally recommended for safety reasons, but this variation was not checked. 

Wear nitrile rubber gloves, laboratory coat, and eye protection. Work in the fume hood. Cover the hydride with a 1 1 1 mixture by weight of sodium or calcium carbonate, clay cat litter (bentonite), and sand. Mix carefully. Place material in a large container behind a safety shield in the hood. Slowly add dry butyl alcohol (31 mL per gram of aluminum hydride). After reaction ceases, slowly and cautiously add water (three times the volume of alcohol added). Neutralize with 6 M hydrochloric acid (prepared by adding concentrated acid to an equal volume of cold water), and let stand until solids settle. Decant the liquid into drain and discard the solid residue as normal refuse.7,8... 

Taking into consideration a) the specific properties of organoaluminum compounds, especially lower aluminumtrialkyls, and their hydride-, halo-gene- and alkoxy derivatives, which are highly flammable in air and explode at contact with water b) the use of hydrogen, ethylene, isobutene, ethylene, isobutene, ethylchloride, sodium and aluminum (finely dispersed and active, which can self-inflame in air), the production of organoaluminum compounds can be considered one of the most dangerous chemical productions. Therefore, safety measures and fire prevention are especially important. 

Ozonides are rarely isolated [75, 76, 77, 78, 79], These substances tend to decompose, sometimes violently, on heating and must, therefore, be handled with utmost safety precautions (safety goggles or face shield, protective shield, and work in the hood). In most instances, ozonides are worked up in the same solutions in which they have been prepared. Depending on the desired final products, ozonide cleavage is done by reductive or oxidative methods. Reductions of ozonides to aldehydes are performed by catalytic hydrogenation over palladium on carbon or other supports [80, 81, 82, S3], platinum oxide [84], or Raney nickel [S5] and often by reduction with zinc in acetic acid [72, 81, 86, 87], Other reducing agents are tri-phenylphosphine [SS], trimethyl phosphite [89], dimethyl sulfide (DMS) [90, 91, 92], and sodium iodide [93], Lithium aluminum hydride [94, 95] and sodium borohydride [95, 96] convert ozonides into alcohols. 

Reduction of ketones. Bernstein and co-workers " found the reduction of the 11-ketosteroid (1) to cortisol 3,20-bisethyleneketal (2) with lithium aluminum hydride unsatisfactory with respect to yield, safety hazard, etc., but found that the reduction can be accomplished in high yield with an exceedingly large excess of sodium... 

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