The Synthesis of Gun Cotton and TATP

Transcription

1 CHEM 121L General Chemistry Laboratory Revision 1.1 The Synthesis of Gun Cotton and TATP Learn about the Synthesis of "Energetic" Materials. Learn about the Safe Handling of Caustic Substances. In this laboratory exercise, we will synthesize two energetic materials; Gunn Cotton and Peroxyacetone (TATP). Both of these materials are "energetic" in the sense that they contain considerable chemical energy which can be released explosively via combustion. Both materials are generated using extremely caustic reagents that must be HANDLED WITH EXTREME CARE. So, all appropriate pre-cautions must be observed when preparing these materials. Peroxyacetone is most likely a mixture of Triacetone Triperoxide (TATP) and other organic peroxides; with TATP being dominant (~95%). Like most organic peroxides, TATP is highly unstable. And, because the ingredients for the preparation of PeroxyAcetone are cheap and readily available, it is becoming the suicide bomber s weapon of choice. In 2001, shoe bomber Richard Reid used PeroxyAcetone as a detonator in his attempt to bomb American Airlines Flight 63 over the Atlantic. It has also been linked to the London subway bombings of July 7, Peroxyacetone was first discovered in 1895 by the chemist Richard Wolffenstien. In quantities of less than 2 grams, the tendency of Peroxyacetone is to combust: 2 C 9 H 18 O 6 (s) + 21 O 2 (g) 18 H 2 O(g) + 18 CO 2 (g) However, the compound is shock sensitive. Under containment, or in quantities greater than 2 grams, Peroxyacetone tends to detonate. This reaction produces a heatless explosion; no heat is generated as a result of the reaction. Because large quantities of gaseous products are formed, the Entropy (S) of the system increases dramatically during combustion, effectively driving the reaction to completion. (Another example of an Entropically driven reaction is the rapid

2 P a g e 2 decomposition of Sodium Azide in your car s airbag, which produces copious amounts of Nitrogen gas but little heat.) Nitrocellulose is a product of the nitration of Cellulose and is highly flammable or explosive depending on the ignition and reaction conditions employed. Used as a propellant or explosive, Nitrocellulose is referred to as Guncotton. Cellulose itself is a polysaccharide composed of numerous 6-Carbon sugar units linked together in a long strand. This is a major component of cotton, lignin, wool and paper. When treated with Nitric Acid, several of the OH groups of the Cellulose molecule are nitrated to ONO 2 units. The longer the treatment, the more complete the nitration; with complete nitration leading to Cellulose Trinitrate.

3 P a g e 3 When ignited in the open, Nitrocellulose decomposes non-explosively according to: Cellulose Trinitrate (9/2) n CO(g) + (3/2) n CO 2 (g) + (7/2) n H 2 O(g) + (3/2) n N 2 (g) Note the decomposition results in completely gaseous products. ( n represents the number of sugar units bound together in the original Cellulose molecules.)

4 P a g e 4 Pre-Lab Questions 1. What mass of Sodium Bicarbonate (NaHCO 3 ) is required to prepare 250 ml of a 1M solution?

5 P a g e 5 Procedure Synthesis of Peroxyacetone 30% Hydrogen Peroxide is a very strong oxidizing agent. In case of contact with your skin, flush the area with Water for 15 minutes. Avoid contact with combustible materials. Avoid contamination as the Peroxide will rapidly decompose and generate large amounts of Oxygen gas. When working with this agent, you must: You must wear safety goggles. You must wear gloves. It is recommended that you wear an apron. 1. Add 4 ml of Acetone to a large test tube. 2. Your laboratory instructor will then add 4 ml of 30% Hydrogen Peroxide to the Acetone. 3. Add 4 drops of Conc. HCl. 4. Allow to stand for minutes. The solid PeroxyAcetone should begin to form. If not, warm the test tube in a Water bath at 40 o C. 5. Allow the mixture to stand for a total of 1 hour. 6. Using a gravity funnel, filter the resulting slurry of PeroxyAcetone. Use a small portions of Water to rinse the solid into the funnel. Open the filter paper and allow it to stand on a watch glass to dry until the next lab period. Remainder to be Completed at the Next Laboratory Session PeroxyAcetone is shock sensitive. Do not drop or jar the solid. Because it is easily combusted, keep the PeroxyAcetone away from all hot surfaces. Do not store the compound for any reason. 7. Very carefully tap the resulting powder into a pre-tared weigh boat. Determine the mass of your sample. You should not ignite more than 0.15g of this sample. If your sample weighs more than 0.15g, separate it into smaller portions and ignite them sparately. 8. Now, place less than 0.15g of the dried PeroxyAcetone in the middle of a filter paper. 9. Place the filter paper containing the Peroxyacetone ona metal Ring attached to a Ring Stand.

6 P a g e Before igniting the sample, put on a pair of Ear Muffles. (This is a safety precaution that is a bit excessive. But, we want to operate within a strict safety margin.) Use a fireplace match attached to a metal rod one meter in length to ignite the sample. Bring the lit match to the solid along a horizontal path to ignite the PeroxyAcetone. 11. When finished, place the filter paper in an appropriate waste container. Synthesis of Gun Cotton Nitric and Sulfuric Acid are Strong Oxidizing Agents, which can cause sever burns. Sulfuric Acid is also a powerful Dehydrating Agent. Mixing conc. Nitric and Sulfuric Acids produces considerable heat. When working with these agents, you must: You must wear safety goggles. You must wear gloves. It is recommended that you wear an apron. All spills must be neutralized with Sodium Bicarbonate. If any should get on your skin, initially flush the area with Ice-Water followed by plenty of Tap-Water. The area should then be treated with Baking Soda.

7 P a g e 7 1. Prepare ml Water Baths and a 250 ml 1M NaHCO 3 Bath. This must be done before proceeding to the next part of the lab. 2. A mixture of 70 ml Conc. Sulfuric Acid and 30 ml Conc. Nitric Acid has been prepared and is available in an ice-bath the Fume Hood. 3. Under the supervision of a laboratory instructor, use tongs to immerse a standard Cotton Ball in the acid mixture for a few minutes. 4. Once the nitration is complete, rinse the Cotton Ball is three successive baths of 500 ml of fresh Water. Allow the Cotton Ball to stand in each bath a few minutes. 5. Immerse the Cotton Ball in 250 ml of 1M NaHCO 3 ; Sodium Bicarbonate. This will react with any excess Acid to produce gaseous Carbon Dioxide: H + (aq) + HCO 3 - (aq) H 2 CO 3 (aq) H2 CO 3 (aq) CO 2 (g) + H 2 O If excess bubbling occurs, repeat the process of rinsing the Cotton Ball. Otherwise, continue rinsing in the Bicarbonate solution until the bubbling ceases. 6. Squeeze dry the Cotton Ball and spread it out to dry. 7. Place the Nitrated Cotton Ball into a small Dixie Cup and allow it to dry until next week. Remainder to be Completed at the Next Laboratory Session 8. Place the Nitrated Cotton Ball on the base of a Ring Stand in the Fume Hood. Using a long match, or a match attached to a metal rod, ignite the Nitrated Cotton Ball.

8 P a g e 8 Data Analysis No Data Analysis. No Lab Report is Due for this Laboratory Exercise.

9 P a g e 9 Post Lab Questions No Post Lab Questions No Lab Report is Due for this Laboratory Exercise.