Lead azide preparation

According to Sudo [96] lead azide prepared by the action of sodium azide on an aqueous solution of lead acetate has a lower ignition temperature (332-336°C) than that obtained by the action on a solution of lead nitrate (339-359°C). 

Study of the Explosive Characteristics of Lead Azide Prepared Commercially 2)Wm.H.Rinkenbach, USP 1,914, 530(1933) "Method of Producing Noncrystalline Explosive Azide 3)W.E.Garner A.S.Gomm, JCS 1931, 2123 34 (Thermal de-compn and deton of LA crysts) 4)F.D. 

An approach which circumvents the problem of the effect of particle-size distribution on decomposition kinetics was adopted by Walker et al [26] and by Fox [10], who worked with individual single crystals or collections of noninteracting particles of uniform size. A typical lead azide preparation of the latter type is shown in Figure 4. Walker et al found that sodium and thallous azides do indeed show induction periods which are dependent upon particle size the... 

Its heat of combustion and heat of detonation are 631 and 368 cal/g, respectively (or 184 and 107 kcal/mol). The released gas volume is 308 cm /g at STP. It forms highly shock-sensitive copper and zinc azides when mixed with the solutions of copper and zinc salts. Its contact with these metals or then-alloys over a period of time results in the formation of their azides, too. Reaction with carbon disulfide is violently explosive. There is a report of an explosion resulting from the addition of calcium stearate in a lead azide preparation (MCA 1962). 

Fig. 4.3 Comparison of lead azide prepared with the colloid agents—dextrin and PVA...

Fig. 4.5 Agglomerates of the dextrinated a-form of lead azide prepared by batch process (left) and the same prepared without addition of crystal structure modifier (right) (by kind permission of Pavel Valenta, Austin Detonator)...

Fig. 4.7 Needles of the P-form of lead azide prepared by the diffusion process captured by optical microscopy...

Lead azide is not readily dead-pressed, ie, pressed to a point where it can no longer be initiated. However, this condition is somewhat dependent on the output of the mixture used to ignite the lead azide and the degree of confinement of the system. Because lead azide is a nonconductor, it may be mixed with flaked graphite to form a conductive mix for use in low energy electric detonators. A number of different types of lead azide have been prepared to improve its handling characteristics and performance and to decrease sensitivity. In addition to the dextrinated lead azide commonly used in the United States, service lead azide, which contains a minimum of 97% lead azide and no protective colloid, is used in the United Kingdom. Other varieties include colloidal lead azide (3—4 pm), poly(vinyl alcohol)-coated lead azide, and British RE) 1333 and RE) 1343 lead azide which is precipitated in the presence of carboxymethyl cellulose (88—92). 

Lead azide, Pb(N3)2, is used as a detonator in car airbags. The impact of a collision causes PMN to be converted into an enormous amount of gas that fills the airbag. A125°C, a saturated solution of lead azide is prepared by dissolving 25 mg in water to make 100.0 mL of solution. What is Kv for lead azide ... 

It is a promising replacement for lead azide in detonators [1], and a remotely controlled procedure for the preparation of this oxygen-balanced compound is described [2]. Preparative methods have been assessed for safety features [3]. 

A solution, prepared by mixing saturated solutions of cadmium sulfate and sodium azide in a 10 ml glass tube, exploded violently several horns after preparation [1], The dry solid is extremely hazardous, exploding on heating or light friction. A violent explosion occurred with cadmium rods in contact with aqueous hydrogen azide [2], A DTA study showed a lesser thermal stability than lead azide [3], It is strongly endothermic (AH°f (s) +451 kJ/mol, 2.32 kJ/g). 

The endothermic nitride is susceptible to explosive decomposition on friction, shock or heating above 100°C [1], Explosion is violent if initiated by a detonator [2], Sensitivity toward heat and shock increases with purity. Preparative precautions have been detailed [3], and further improvements in safety procedures and handling described [4], An improved plasma pyrolysis procedure to produce poly (sulfur nitride) films has been described [5], Light crushing of a small sample of impure material (m.p. below 160°C, supposedly of relatively low sensitivity) prior to purification by sublimation led to a violent explosion [6] and a restatement of the need [4] for adequate precautions. Explosive sensitivity tests have shown it to be more sensitive to impact and friction than is lead azide, used in detonators. Spark-sensitivity is, however, relatively low [7],... 

Our new method of isolating sodium nitrotetrazolate dihydrate produces material in high yield, without the intermediate handling of sensitive explosive compounds. This produced NaNT is of sufficient purity for the preparation of DBX-1 of the quality that is required to replace lead azide. However, it does appear that the DBX-1 used as a seed crystal in the synthesis of DBX-1 influences the behavior of the end product. 

The need for great care to avoid the possibility of detonation of perchloryl compounds by exposure to shock, overheating or sparks is stressed. The compounds are generally more sensitive to impact than mercury fulminate and are of comparable sensitivity to lead azide [1], A range of highly explosive alkyl perchlorates [2] and perchlorylamines [3] have been prepared by interaction of dichlorine heptaoxide with alcohols or amines in carbon tetrachloride solution. The solutions of the products were not sensitive to mechanical shock and could... 

For the terrorist, TATP and HMTD offer easy sources of primary explosives. Consulting the do-it-yourself literature, it can be seen that there are two other commonly recommended primary explosives—lead azide Pb(N3)2 and mercury fulminate Hg(ONC)2, but these are difficult to prepare cleanly. The synthesis of diazodinitrophenol (DDNP) (Fig. 2.5), common in commercial detonators, is reported in such publications, but apparently is rarely attempted by clandestine chemists. Typically, the brisance of a primary is less than TNT, but the efficacy is the fact that a shock wave can result from a relatively mild insult. 

Lead azide is prepared by the reaction of sodium azide with lead nitrate 2NaN3 + Pb(N03)2 Pb(N3)2 + 2NaN03... 

Silver Azide, Cadmium Azide, Cupric Azide, Triazidotrinitrobenzene, Chloratotrimercuraldehyde, Nitrogen Suifide Hexamethylenetriperoxidediamine Until WWI, Mercuric Fulminate was the principle initiating agent used, but Lead Azide has now replaced it. Lead azide is not the most powerful azide, but is more stable and less dangerous to handle than some of the other ones. Cadmium Azide, for example, is more powerful than Lead Azide but is unsuitable as an initiating agent because it is difficult to prepare and is soluble in water... 

Lead azide [Pb(N3)2] (LA) is a salt of hydrazoic acid (N3H, highly poisonous) and is prepared by reacting solutions of sodium azide and lead acetate or nitrate. This exists in two forms the a form (orthorhombic and stable) and P form (monoclinic) which has a tendency to revert back to the a form. The P form is much more sensitive. The two forms differ in their rate of decomposition when heated. Crystalline LA is stored in dry conditions because it becomes more sensitive when... 

The introduction of LA into commercial detonators resulted in an unacceptably high level of explosions during manufacture and use and hence its use was discontinued until it could be prepared in less sensitive form. A number of methods have been used to prepare LA in a less sensitive form. The main control of properties is by synthesis rather than by any other approach. Lead azide compositions RD 1343 (improved CMC co-precipitated LA), RD 1352 (improved dextrinated LA) and Service lead azide (SLA) illustrate some modified LAs which are used depending on the requirements. Different processes developed for the modification of LA may be summarized as follows ... 

Service lead azide (SLA) SLA is prepared by double decomposition of lead acetate and sodium azide in the presence of sodium carbonate and acetic acid. 

Redman, L.D., and Spear, R.J. (1983) Mercuric-5-Nitrotetrazole a possible replacement for lead azide in Australian ordnance. Part I an assessment of preparation methods. Materials Research Laboratory, Melbourne, Report No. MRL-R-901 Chem. Abstr., (1984) 100,194540. 

Surve, R.N. (1992) Ph.D. Thesis entitled, Studies on The Preparation and Properties of Basic Lead Azides, University of Poona. 

Lead azide can exist in two allotropic forms the a-form is orthorhombic, the / -form monoclinic. (Miles [75], Garner and Gomm [37]). The crystallographically stable modification is the a-form. It is prepared by rapidly stirring a solution of sodium azide with a solution of lead acetate or lead nitrate. 

Precipitation. In a dissolving vessel a solution of sodium azide is prepared in distilled water and then aqueous sodium hydroxide is added. The quantity of sodium hydroxide used depends on the amount of lead azide to be produced. The solution... 

From the magnesium styphnate solution so prepared, 86.4 1. of liquid was decanted, leaving the lower layer in which the sediment was collected. This solution was heated to 60°C, while stirring, and 22.71. of 34% solution of lead nitrate, s.g. 1.274 (31°Be) was then poured into it during a period of 20-30 min, while stirring continued and the temperature was maintained at 60°C. When the solutions were mixed, the contents of the reactor were cooled as quickly as possible to 25°C when this temperature has been reached the stirrer was stopped and the precipitated sediment of lead styphnate was allowed to settle. The liquid from above the sediment Was then decanted, and the latter was first washed out of the reactor by a stream of water, and transferred onto a cloth filter, where it was washed again as is the custom with other primary explosives. From the above mentioned amounts of raw material about 8 kg of lead azide was obtained. 

The continuous preparation of lead styphnate can be carried out in the same equipment as for the manufacture of lead azide (Fig. 50) after previous cleaning of the apparatus and exchanging the flowmeters. 

Lead azide (PbN6) (2.2) was first prepared by Curtius in 1891. 

Lead azide can exist in two allotropic forms the more stable a-form which is orthorhombic, and the /1-form which is monoclinic. The a-form is prepared by rapidly stirring a solution of sodium azide with a solution of lead acetate or lead nitrate, whereas the /1-form is prepared by slow diffusion of sodium azide in lead nitrate solutions. The /1-form has a tendency to revert to the a-form when its crystals are added to a solution containing either the a-form crystals or a lead salt. If the /1-form crystals are left at a temperature of 160 °C they will also convert to the a-form. Some of the properties of lead azide are presented in Table 2.3. 

Lead azide (7.12) is prepared by dissolving lead nitrate in a solution containing dextrin, with the pH adjusted to 5 by adding one or two drops of sodium hydroxide. 

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