LEAD SALTS OF NITRO COMPOUNDS

This class of compounds showing explosive instability deals with heavy metals bonded to elements other than nitrogen and contains the separately treated groups GOLD COMPOUNDS LEAD SALTS OF NITRO COMPOUNDS LITHIUM PERALKYLURANATES MERCURY COMPOUNDS METAL ACETYLIDES METAL FULMINATES METAL OXALATES PLATINUM COMPOUNDS PRECIOUS METAL DERIVATIVES SILVER COMPOUNDS... 

Lanthanide iodide silicides, 200 Lanthanide metals, 200 Lanthanide nitrobenzoates, 200 Lanthanide—transition metal alloy hydrides, 201 Lassaigne test, 201 Lead salts of nitro compounds, 201 Lecture demonstrations, 202 Light alloys, 202 Lime fusion, 202 Linseed oil, 202 Liquefied gases, 203 Liquefied natural gas, 203 Liquefied petroleum gases, 203 Liquid air, 204 Liquid nitrogen cooling, 205 Lithium peralkyluranates, 205 Lubricants, 205 Lycopodium powder, 205... 

A general method for nitrone formation is based on the interaction of nitro compounds with carbanions. Interaction between nitroso compounds (175) and anions of aliphatic nitro compounds (178) leads to nitrones (179). The source of anions are metal salts of nitro compounds, triethylamines, and trimethylsilylni-tronates (Scheme 2.63) (334, 335). 

Aminophenols which were formerly obtained only by the reduction of nitro-compounds in concentrated sulphuric aoid can now be prepared by reducing dilute acid suspensions of nitro-compounds, provided the mixture be well stirred and the cathode surfaces made up. of two or more metals. This improved process, which it is claimed gives good yields of amino-hydroxy bodies, is due to the Society of Chemical Industry, Basle.1 When an indifferent cathode is employed, the addition of certain metals in the form of salts or finely powdered metal to the electrolyte increases the yield of amine at the expense of amino-hydroxy compound such are copper, iron, or lead if added separately. If, however, two at least of these and other metals be added, reduction to aminophenol is favoured. 

Aromatic amines are prepared by the reduction of nitro compounds under acidic conditions this leads to the protection of the resultant amine as the salt. The selective reduction of one nitro group in 1,3-dinitrobenzene can be achieved with sodium polysulfide. 

Metal salts or complexes have a role in promoting dehydration of nitro compounds. Thus, 5-phenylisoxazole has been obtained in low yield from the lithium salt of phenylacetylene with nitromethane in dioxan at room temperature [24]. The complex tetrakis(triphenylphosphane) platinum(O) on treatment with nitromethane leads to fulminatobis(triphenylphosphane)platinum(II), possibly via CT-nitromethyls [25-27]. Cerium and other metal nitrates have been claimed to promote condensation of nitro compounds with alkenes [28]. More examples of condensations caused by transition metal salts are reported in Section 8.2.4. 

It has been observed that the majority of remedies for preventing the development of flash lead to an increase of smoke (e.g. potassium salts give white smoke, aromatic nitro compounds give black-grey smoke due to the presence of unburnt carbon). Nitroguanidine is the only additive that does not appreciably increase smokiness. The burning of blackpowder in the primer produces an insignificant amount of smoke. 

Among all the possible nitro derivatives of resorcinol only di- and tri-nitroresorci-nols are of practical value. Both are used as initiating explosives in the form of lead salts (Vol. III). The lead salt (Pb2+) of dinitroresorcinol is also of some practical value and in this connection some data characteristic of the compound will be given. 

The power of green chemistry" is nicely illustrated by reference to the production of aromatic acids. Classical methods using chlorine or nitric acid have been largely displaced by catalytic oxidations with dioxygen (see Fig. 4.48). This leads to high atom utilization, low-salt technology, no chloro- or nitro-compounds as by-products and the use of a very cheap oxidant. 

Treatment of 2,2,2-trifluoro-] -phenylethanone (6) and (trifluoromethyl)benzene (8) with ozone or ozonized air in chlorinated hydrocarbons, and in the presence of excess nitrogen dioxide and a catalytic amount of an iron(Hl) salt at - 10 to O C, leads to the respective nitro compounds 7 and 9 in good to excellent yields. The reaction is clean and rapid, and little or no hydrolysis of the trifluoromethyl moiety is observed during the nitration. ... 

---