Explosive Theory

This website is contains information about the chemistry behind explosives

Friday, December 08, 2006

TNT

Yet another TNT synth, this one from Megalomania.

Trinitrotoluene
melting point
80.1 °C boiling point
ignites at 295 °C trinitrotoluene molecular mass
227.13 g/mol density
1.654 g/mL
table key sensitivity
very low chemical formula
C7H5N3O6 explosive velocity
7028 m/s estimated cost
$?.00/g


2,4,6-trinitrotoluene, or just TNT, is the oft used military and industrial explosive that may be the among the best recognized explosive around. Other names for TNT include: trinitrotoluol; sym-trinitrotoluene; a-trinitrotoluol; 2-methyl-1,3,5-trinitrobenzene; entsufon; 1-methyl-2,4,6-trinitrobenzene; methyltrinitrobenzene; tolite; trilit; s-trinitrotoluene; s-trinitrotoluol; trotyl; sym-trinitrotoluol; alpha-trinitrotoluol; tolite; triton; tritol; trilite; tri; tutol; trinol; füllpulver 1902; Fp02; tritolo; trillit; tolita; tol; and trotil. TNT was first synthesized in 1863 by a scientist named Wilbrand who treated toluene with sulfuric and nitric acid at near boiling temperatures. Although there are several isomers of trinitrotoluene, only the 2,4,6- isomer is of importance. Pure TNT is in the form of small columns or needles and is insoluble in water. It is quite stable, being meltable ,or able to act like a plastic at around 50 °C. TNT can even be boiled although the experiments did this under reduced pressure (50mm Hg) to lower the boiling point to around 245 °C. The normal detonation temperature is 333 °C, the calculated boiling point at normal atmospheric pressure is 345 °C, so don't do it. Some experiments have determined that the presence of foreign material like 1.9% of Fe2O3 will lower the amount of time it takes for TNT to explode once it reaches its critical temperature, or 295 °C, the temperature at which decomposition begins. Also, mixing pure sulfur with TNT will lower the initiation temperature and increase the explosive power. For example, pure TNT explodes at 333 °C, 5% sulfur explodes at 304 °C, 10% sulfur at 294 °C, 20% sulfur at 284 °C, and 30% sulfur at 275 °C. The increase in explosive power is gained through the addition of 5-10% sulfur. Because the stability of TNT is so great, it is harder to detonate it, the sensitivity increases somewhat above 80º C, but is still rather low even when molten. A powerful blasting cap, or booster charge, will be needed to detonate TNT. This lab is carried out in three separate operations, forming mononitrotoluene, then dinitrotoluene, and finally trinitrotoluene.
CHEMICALS APPARATUS
ethyl alcohol 100/500/600-mL beaker
nitric acid Buchner funnel
sodium bisulfite graduated cylinder
sulfuric acid pipet/buret
toluene separatory funnel
water stirrer/stirring rod
thermometer


Prepare a nitrating solution of 160 mL of 95% sulfuric acid and 105 mL of 75% nitric acid in a 500-mL beaker set in a salt-ice bath. Mix the acids very slowly to avoid the generation of too much heat. Allow the mixture to cool to room temperature. The acid mixture is slowly added dropwise, with a pipet or buret, to 115 mL of toluene in a 600-mL beaker while stirring rapidly. Maintain the temperature of the beaker during the addition at 30-40 °C by using either a cold water or salt-ice bath. The addition should require 60-90 minutes. After the addition, continue stirring for 30 minutes without any cooling, then let the mixture stand for 8-12 hours in a separatory funnel. The lower layer will be spent acid and the upper layer should be mononitrotoluene, drain the lower layer and keep the upper layer.

Dissolve one-half of the previously prepared mononitrotoluene and 60 mL of 95% sulfuric acid in a 500-mL beaker set in a cold water bath. Prepare a nitrating solution of 30 mL of 95% sulfuric acid and 36.5 mL of 95% nitric acid in a 100-mL beaker. Preheat the beaker of mononitrotoluene to 50 &Deg;C. Very slowly add the nitrating acid to the beaker of mononitrotoluene, with a pipet or buret, drop by drop while stirring rapidly. Regulate the rate of addition to keep the temperature of the reaction between 90-100 °C. The addition will require about 1 hour. After the addition, continue stirring and maintaining the temperature at 90-100 °C for 2 hours. If the beaker is allowed to stand, a layer of dinitrotoluene will separate, it is not necessary to separate the dinitrotoluene from the acid in this step.

While stirring the beaker of dinitrotoluene, heated to 90 °C, slowly add 80 mL of 100% fuming sulfuric acid, containing about 15% SO3, by pouring from a beaker. Prepare a nitrating solution of 40 mL of 100% sulfuric acid, with 15% SO3, and 50 mL of 99% nitric acid. Very slowly add the nitrating acid to the beaker of dinitrotoluene, with a pipet or buret, drop by drop while stirring rapidly. Regulate the rate of addition to keep the temperature of the reaction between 100-115 °C. It may become necessary to heat the beaker after three-quarters of the acid has been added in order to sustain the 100-115 °C temperature. The addition will require about 90-120 minutes. Maintain the stirring and temperature at 100-115 °C for 2 hours after the addition is complete. Allow the beaker to sit undisturbed for 8-12 hours, it should form a solid mass of trinitrotoluene crystals. Pour the contents of the beaker over a Buchner funnel without any filter paper to collect the bulk of the crystals, save the acidic filtrate as well. Break up the collected crystals and wash them with water to remove any excess acid. Add the collected acid and wash filtrates to a large volume of water, this will cause any remaining trinitrotoluene to precipitate. Decant off as much of the water as possible and combine these crystals with the previous ones on the funnel. Drown the crystals in a large volume of water, filter to collect them, and wash several times with water. Wash the crystals by adding them to a beaker of water, heat the water enough to melt the crystals while stirring rapidly. Repeat the melting and stirring with a fresh batch of water three or four times to wash thoroughly. After the last washing, the trinitrotoluene is granulated by allowing it to cool slowly under hot water while the stirring is continued. Filter to collect the crystals and allow to dry. The TNT can be further purified by recrystallizing from ethyl alcohol, dissolve the crystals in 60 °C and allow the solution to cool slowly. A second method of purification is to digest the TNT in 5 times its weight of 5% sodium bisulfite solution heated to 90 °C while stirring rapidly for 30 minutes. Wash the crystals with hot water until the washings are colorless, then allow the crystals to granulate as before. You will need a graduated cylinder for measuring liquids, a stirring rod or magnetic stirrer for mixing, and a thermometer to monitor the temperature.

HMX

HMX
melting point
281 °C

HMX molecular mass
296.16 g/mol

density
1.903 g/mL

sensitivity: very low

chemical formula
C4H8N8O8

explosive velocity
9110 m/s

HMX is a very powerful military explosive with similar properties to RDX, the other great military explosive with which it is often mixed. HMX is technically called octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, other names include 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane; cyclotetramethylene tetranitramine; and octogen. HMX is itself an acronym for either High velocity Military eXplosive, or Her Majesties eXplosive depending on what country you are in. HMX is very stable, it requires a powerful detonator or booster charge to detonate. It was first developed during WWII in the never ending search for more powerful bombs.
CHEMICALS APPARATUS
acetic acid 500/1000-mL beaker
acetic anhydride 500-mL Florence flask
ammonium nitrate graduated cylinder
methenamine stirrer/stirring rod
nitric acid thermometer
paraformaldehyde
water


Prepare a solution of 748 mL of glacial acetic acid, 12 mL of acetic anhydride, and 17 g of paraformaldehyde, keep this solution at 44 °C while mixing. Prepare a second solution of 217.6 g of ammonium nitrate and 154.6 mL of 99% nitric acid in a 500-mL beaker. Prepare a third solution of 101 g of methenamine, 157 mL of glacial acetic acid, and 296 mL of acetic anhydride in a 1000-mL beaker. Combine the third solution with 112.5 mL of the second solution. Add this combined solution to the first solution over a 15 minute period while stirring rapidly. After the addition, continue stirring for an additional 15 minutes. Next, carefully add 296 mL of acetic anhydride, then carefully add the remainder of the second solution, then add another 148 mL of acetic anhydride, all while stirring. Continue the stirring for 1 hour more. After stirring, add 350 mL of hot water and reflux the whole works for 30 minutes. After this time, cool the liquid down to 20 °C by adding ice. Decant off as much of the liquid from the precipitate as possible and drown the remaining crystals with cold water. Filter to collect the crystals of HMX and wash them with three portions of cold water, allow to dry. The yield is about 95%. You will need a graduated cylinder for measuring liquids, a stirring rod or magnetic stirrer for mixing, and a thermometer to monitor the temperature.

Owing to the large volume of reactants in this lab, in excess of 2.5 L, it is necessary to use a 5-L flask, unfortunately this is beyond most laboratories, and especially the home chemist. This reaction can be carried out in a glass gallon jug or similar large capacity glass container. The refluxing step can be done in portions using a round-bottomed 500-mL Florence flask.

CL- 14

CL-14, a code name for 5,7-diamino-4,6-dinitrobenzofuroxan, is an insensitive high explosive compound. Other names for this explosive include 5,7-dinitro-2,1,3-benzoxadiazole-4,6-diamine 3-oxide; 5,7-dinitro-4,6-benzofurazandiamine 3-oxide; and 4,6-dinitro-5,7-diaminobenzofuroxan. CL-14 is classed as an insensitive, thermally stable, high density explosive, a class of explosives the military is very interested in nowadays. CL-14 is more powerful than the usual lineup of explosives including TATB, TNT, RDX, and the like. CL-14 can be used either alone or in admixture with other high explosives.

Prepare a solution of 7.2 g of 4,6-dinitrobenzofuroxan dissolved in 100 mL of water. Add 14.4 g of potassium bicarbonate and 8.3 g of hydroxylamine hydrochloride to the solution and stir for 3.5 hours at 25 C. The reaction mixture is then cooled to 0 C and 100 mL of 4N potassium hydroxide solution cooled to 0 C is added. Stirring is continued for 3.5 hours at 0 C. Filter to collect the yellow potassium salt of CL-14. Place the yellow solid in a beaker with water at room temperature. Add an excess of 1N hydrochloric acid and stir for 1 hour. The yellow solid is filtered to collect it, washed with 50 mL of water, and dried. Synthesis 2: 4.16 g of hydroxylamine hydrochloride is added to a stirred solution of 40.0 g of 85% KOH made up to 300 mL with water at a temperature of 5 C. To this mixture, 5.33g of 7-amino-4,6-dinitrobenzofuroxan (ADNBF) is added, with stirring, at 5 C. Initially, a transient bright-red color appeared then changed to an orange color. Solid particles may be visible in the stirred reaction mixture. Stirring is continued at 5 C for 5 hours. The reaction mixture is poured into 500 mL of ice water and stirred for 15 minutes. The fine yellow solid is filtered to collect it, washed with two 50 mL portions of ice water, and dried to give 4.51 g (69.4% yield) of the potassium salt of CL-14. The potassium salt is stirred with 50 mL of 3N hydrochloric acid for 30 minutes, the yellow solid is filtered to collect it, washed with 50 mL of water, and dried to give 3.69g (65.2% yield) of CL-14.
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