The procedure is exactly the same as the one outlined above, except a smaller amount of salicyclic 0,6grams per 1ml h 2 so 4 and 1,5ml hno 3 our acetylsalicylic 0,5g per 1ml h 2 so 4 and 1,5ml hno 3 acids are used. Chemistry reagent manual prepared by chemistry department, sgtb khalsa college page 9 under dbts star college scheme iv. We use ethanol to extract the asa which is separated via filtra. It must be kept wet with water usually 30% or more because the dry solid is explosive. Workers making picric acid during world war i were called canaries because their skin was stained yellow 6. Picric acid can also be produced from phenol derivatives such as salicylic and acetylsalicylic acids. Persistence and degradability picric acid, saturated. Instead, you heat the phenol with sulfuric acid to get mostly phenol2,4disulfonic acid. Making picric acid via a nitration of acetylsalicyllic acid or more commonly known as asprin. To get round this, sulphonation of anhydrous phenol is carried out uisng fuming sulfuric acid. Y is reacted with concentrated nitric acid to form z. Picric acid is a cnitro compound comprising phenol having three nitro substtituents at the 2, 4 and 6positions.
Organic preparations and procedures international 2017, 49 2, 178181. You can prepare phenols in large quantities by the pyrolysis of the sodium salt of benzene sulfonic acid, by the dow process, and by the air oxidation of cumene. Electrondonating substituents make a phenol less acidic by destabilizing the phenoxide ion resonance effect the location of the substituent relative to the phenol is important 87 17. Make sure that any picric acid disposed of still has some water content. Identify y and z and explain why phenol is not converted commercially to z by reacting it with conc. Phenol, c 6 h 5 oh when it first reacts with concentrated sulphuric acid, forms y. The hot picric acid solution is decanted from the residue of impurities, and on cooling the second crop of picric acid crystals is obtained. Full text of the preparation of salicylic acid from phenol. This yields phydroxyphenylsulphonic acid which can then be nitrated using conc nitric acid. My textbook says nowadays picric acid is prepared by treating phenol first with concentrated sulfuric acid which converts it to phenol 2,4disulfuric acid and then with concentrated nitric acid to get 2,4,6trinitrophenol my question.
The yield of pure distilled salicylic acid is 125 gms. British chemist peter woulfe discovered picric acid in 1771. Phenol is a very weak acid and the position of equilibrium lies well to the left. Picric acid, saturated safety data sheet according to federal register vol. The sulfonic acid groups are so electronwithdrawing that nitration can proceed more slowly and at a controllable rate. This causes the displacement of the sulphonic group and the introduction of nitro groups which yield the required product picric acid 2,4,6trinitrophenol. Picric acid was used as a grenade and mine filling.
Structure, properties, spectra, suppliers and links for. Preparation of some common reagents this section deals with the preparation of some common chemical reagents. Organic contaminants like phenol, ethanol and aromatic compounds absorb at 230 therefore 260230 should be at least 1. Phenol is the organic compound containing benzene ring bonded to a hydroxyl group. Chemistry notes for class 12 chapter 11 alcohols, phenols. Test the ph periodically and do not use if the ph is of phenol from biooil produced from pyrolysis of agricultural wastes.
Recommendations for immediate medical carespecial treatment. The name picric comes from the greek pikros, meaning bitter, reflecting its bitter taste. Alkenes react with water in the presence of acid as catalyst to form alcohols. Picric acid is an organic compound with the formula o 2 n 3 c 6 h 2 oh. The procedure is exactly the same as the one outlined above, except a smaller amount of salicyclic 0,6grams per 1ml h 2 so 4 and 1,5ml hno 3 our acetylsalicylic 0,5g per 1ml h 2. Picric acid is prepared by dissolving phenol in sulfuric acid and subsequent nitration of the resulting phenoldisulfonic acid with nitric acid or by further nitration of dinitrophenol prepared from dinitrochlorobenzene.
The first product is probably 6nitrophenol2,4disulfonic acid. Synthesis of phenols book summaries, test preparation. Presence of electron withdrawing group increases the acidity of phenol by, stabilising phenoxide ion while presence of electron releasing group decreases the acidity of phenol by destabilising phenoxide ion. Let cool over night, picric acid will fall out and form beautiful cristals. Picric acid is a trinitroaromatic compound frequently found in forensic and histology laboratories as a staining and fixative agent. Read the full msds for more details before handling. You can taste and smell phenol at levels lower than those that are associated with harmful effects. Sciencemadness discussion board picric acid with phenol. Phenol is both a manufactured chemical and a natural substance.
Guidance document safe handling of picric acid this is a brief summary. Recommended use and restrictions on use use of the substancemixture. Instead, you heat the phenol with sulfuric acid to get mostly phenol 2,4disulfonic acid. Preparation of buffer saturated phenol for dna extraction. An increase in the yield and purity of the picric acid synthesized from phenol can be achieved by changing the parameters of the medium. If you decide to dispose of your wet picric acid, some options are available. You can also prepare small amounts of phenol by the peroxide oxidation of phenylboronic acid and the hydrolysis of diazonium salts. It has a role as an explosive, an antiseptic drug and a fixative. Only one peak, probably of 6nitrophenol2,4disulphonic acid, was detected. The buffer saturated phenol may be stored at 4c for 1 month for dna extraction. The chemistry of preparation of sali cylic acid by the method proposed by schinitt was explained by s. Take 100g phenol bottle to fume hood, open it, and pour in 100 ml 50 mm triscl ph 8. In a basic medium, lead acetate produces a bright yellow precipitate, lead picrate.
If you wantneed 250500ml of equilibrated phenol, use a ml bottle. In preliminary studies, we were able to establish that the direct synthesis of picric. Picric acid should be disposed as a hazardous waste within 2 years of initial receipt. However, phenol is sufficiently acidic for it to have recognizably acidic properties even if it is still a very weak acid. Determination of tea polysaccharides in camellia sinensis by a modified phenol sulfuric acid method 671 volume of concentrated sulfuric acid.
Take a glass flask, cover the bottom with the wet picric acid about 5 mm in 1 litre flask, fill with deion. Phenol reacts with dilute nitric acid at room temperature to give a mixture of 2nitrophenol and 4nitrophenol while with concentrated nitric acid, more nitro groups get substituted on the ring to give 2,4,6trinitrophenol which is known as picric acid. Preparation of picric acid chemistry stack exchange. Aqueous solutions of phenol are weakly acidic and turn blue litmus slightly to red. Reagents acid phenol to solid phenol add rnasefree water until there is a layer of water on top of. Nitro groups are a handy functional group as they can be. If the solution is boiled down to about 700ml volume, the impurities will precipitate as a molten, undissolved, reddishbrown blob in the boiling picric acid solution.
Picric acid is obtained by nitration of phenol by concentrated hno3 in presence of concentrated h2so4. Jan, 2016 to get round this, sulphonation of anhydrous phenol is carried out uisng fuming sulfuric acid. In case of unsymmetrical alkenes, the addition reaction takes place in accordance with markovnikovs rule unit, class xi. Contact ehs for disposal for wet solutions of picric acid only. The name picric comes from the greek pikros, meaning bitter, reflecting its. Add nitric acid and sulfuric acid to phenol, and the phenol will be nitrated, meaning a nitro group will be added to the aromatic ring. Phenol has a distinct odor that is sickeningly sweet and tarry. Phenol is a highly important industrial chemical because it serves as the raw material for a large number of commercial products such as aspirin, dyes, phenol formaldehyde polymer etc. Picric acid, wet, with not less than 10% water undergoes vigorous reactions with both oxidizing or reducing agents. Test the ph periodically and do not use if the ph is buffering procedure.
Picric acid safety guidelines concordia university. Why is this a better method than simply treating phenol with concentrated nitric acid to obtain picric acid. Preparation of picric acid revisited and revised youtube. The french 4stage process from phenol mostly was good for making dnp which they preferred to admix with picric acid anyway. This topic explains the preparation of phenols from haloarenes, benzene sulphonic acid, diazonium salts, cumene. Phenol is a highly important industrial chemical because it serves as the raw material for a large number of commercial products such as aspirin, dyes, phenolformaldehyde polymer etc. It derives from a 1,3,5trinitrobenzene and a phenol. A hydrogen ion can break away from the oh group and transfer to a base.
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