Dinitroresorcinol preparation

During the preparation of dinitroresorcinol, too low a concentration of nitric acid (82%) led to formation of tarry material, some of which remained in the nitrator discharge line. In the following batch, the tar decomposed in contact with higher strength acid, leading to an explosion. 

The sulfonation-nitration strategy also provides a route to styphnic acid (5) (2,4,6-trinitroresorcinol) from resorcinol (22) but the control of temperature in this reaction is very important. The synthesis of styphnic acid (5) from the nitration of 2,4-dinitroresorcinol (24) with mixed acid or concentrated nitric acid is a higher yielding route. 2,4-Dinitroresorcinol (24) is conveniently prepared from the nitrosation of resorcinol (22) followed by oxidation of the resulting 2,4-dinitrosoresorcinol (23) with dilute nitric acid. 2,4-Dinitrosoresorcinol (23) also generates styphnic acid (5) on treatment with concentrated nitric acid. ... 

This substance is prepared by the action of a hot solution of lead nitrate on a solution of sodium dinitroresorcinate. The lead salt is precipitated as the solution cools. Lead dinitroresorcinate ignites from a direct flame readily and burns with great velocity. Its initiating action is weaker than that of lead styphnate and it is less sensitive to impact and friction than styphnate. It has therefore recently found application as a component of cap compositions. It is valuable because it is safer to handle than styphnate. The preparation of dinitroresorcinol is discussed in Vol. I, p. 536. 

Oxidation of nitrosophenols. This method is applied when fewer nitro groups are to be introduced on the ring than those obtained by way of nitration. It is also applied when a pure product, free from its isomers, is to be prepared, e.g. p- nitro-phenol from phenol. Direct nitration of phenol yields a mixture of the o- and p- isomers, dinitrophenol being readily formed as a by-product. Similarly dinitroresorcinol may be obtained by oxidation of dinitrosoresorcinol (p. 537). 

Since the nitration of resorcinol by the conventional method for phenols (i.e. sulphonation followed by the action of nitric acid) yields a trinitro derivative, two other methods for the preparation of dinitroresorcinol are possible, viz. oxidation of dinitrosorcsorcinol or nitration of resorcylic acid followed by decarboxylation. 

Dinitrosoresorcinol is oxidized with 50% nitric acid at a temperature below 0°C. Moist, freshly prepared dinitrosoresorcinol is charged into the reactor, containing nitric acid cooled down to -5°C. When calculating the concentration of nitric acid, the water content in dinitrosoresorcinol should be taken into account. Simultaneously with the dinitrosoresorcinol concentrated nitric acid is introduced into the reactor to keep the concentration of the acid in the reactor constant. After the reaction has been completed, the reactor contents are run out into icy water. The volume of the water containing ice should be several times as large as that of the product. Dinitroresorcinol is precipitated and is separated on a vacuum filter and washed with a small quantity of cold (ca. 0°C) water. The crude product contains some trinitroresorcinol. By crystallization from hot water a product is obtained which should not melt below 147°C. The yield of the reaction, calculated on the resorcinol used, is about 30% of the theoretical. 

Summary 4,6-Dinitroresorcinol is prepared by the action of 70% nitric acid on resorcinol diacetate. Some urea is added in-order to control the nitration and ensure no by-product nitrosation takes place. After the addition of the 70% nitric acid, the intermediate produced is treated with 90% nitric acid yielding the 4,6-dinitroresorcinol as a golden yellow solid. Commercial Industrial note For related, or similar information, see Application No. 001,243, January 7,1987, by SRI International, to Robert J. Schmitt, (Mountain View, CA, David S. Ross, Palo Alto, CA, James F. Wolfe, Palo Alto, CA. Part or parts of this laboratory process may be protected by international, and/or commercial/industrial processes. Before using this process to legally manufacture the mentioned explosive, with intent to sell, consult any protected commercial or industrial processes related to, similar to, or additional to, the process discussed in this procedure. This process may be used to legally prepare the mentioned explosive for laboratory, educational, or research purposes. 

Summary Styphnic acid can be prepared by nitrating resorcinol in a two-step process. The first step is the preparation of dinitroresorcinol, which is prepared by the reaction of resorcinol with sodium nitrite and sulfuric acid. The dinitroresorcinol is converted into styphnic acid by treatment with dilute nitric acid. The product is then precipitated, washed, and then dried. The... 

LDNR is generally prepared from 2,4-dinitroresorcinol and soluble lead salt (nitrate or acetate) via the sodium salt (introduced as sodium carbonate). The reaction is carried out in hot or boiling water [8-10, 14, 15]. 

The form prepared by Taylor et al. [21] and mentioned in [24] is made of basic salt containing 3 molecules of lead 4,6-dinitroresorcinol and 2 molecules of lead hydroxide - 3[PbDNR]-2Pb(OH)2 further reported as 2/3 salt. The ratio of lead to DNR in this substance is 5 3. The 2/3 basic lead salt has a density 3.65 g cm and it is practically insoluble in water (0.01 g/100 ml). The salt is compatible with common metals and oxidizers and stable under water for a long time (no change was observed over a period of 1 year) [24]. 

The most frequently described, and probably the only lead salt that has been practically used, is monobasic lead 4,6-dinitroresorcinol, mostly called just basic lead 4,6-dinitroresorcinol. It can be prepared in two forms— yellow and red (see Table 5.3) both having the same chemical and explosive properties [15],... 

Preparation of various basic salts is based on the reaction of either (a) lead nitrate in a basic environment (NaOH) or (b) freshly prepared lead hydroxide (precipitated from aqueous solutions of lead acetate and sodium hydroxide) with 4,6-dinitroresorcinol or its salts. 

The form of the product (Table 5.4) depends on the reaction conditions (amount of lead compound, temperature, reaction period, pH, rate and order of addition of reactants) [24]. The following forms are reported based on the temperature of the reaction mixture acid 50-60 °C preferably 55 °C, normal 40-50 °C preferably 45 °C, and 2/3 basic at 18-28 °C preferably 23 °C [25]. The particular basic salts are formed from exact molar proportions of lead salts in a basic environment (NaOH) [14, 15, 22]. The manufacturing process of 2/3 basic salt (RD 1353) has been described by Jenkins [24]. The normal salt is prepared from 4,6-dinitroresorcinol in an aqueous suspension of freshly prepared lead hydroxide [25]. Crystal modifiers (e.g., carboxymethyl cellulose) are recommended for preparation of the product in a more suitable form for processing [26, 27]. 

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