Extraction Of Salicylic Acid

Extraction Of Salicylic Acid

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INTRODUCTION: In this experiment, I will be extracting salicylic acid using various processes. Esters like methyl salicylate are found in nature, and can be converted into salicylic acid. It is obtained as oil of wintergreen which used to be made by dry distillation of the leaves of the evergreen shrub. The salicylic acid will be obtained from the methyl ester by the process of hydrolysis, using dilute sodium hydroxide solution. AIM: The aim of this experiment is to extract salicylic acid from methyl esters using hydrolysis. CHEMICALS: Cyclohexane Glacial ethanoic acid Ethanol Ethyl ethanoate Concentrated hydrochloric acid 2-hydroxybenzoic acid (salicylic acid) Iodine Methyl 2-hydroxybenzoate, methyl salicylate (oil of wintergreen) Sodium hydroxide solution RISK ASSESMENT: CHEMICAL

HAZARD

Cyclohexane

Highly flammable

Glacial ethanoic acid

Corrosive, flammable

DERRICK ABAITEY

SAFETY PRECAUTIONS If swallowed wash out with water and drink two glasses of water, if you are having difficulties in breathing seek for medical attention. If it splits into your eyes tap water into it for about 10 minutes. If it splits on your clothes remove contaminated clothing and if splits on your skin wash the contaminated area with water. Wear goggles for eye protection, gloves and lab coat. Wash out with water and drink at least one glass of water, if swallowed, if having difficulty in breathing seek for medical attention. If splits into your eye tap

Extraction Of Salicylic Acid

Ethanol

Highly flammable

Ethyl ethanoate

Highly flammable

Concentrated hydrochloric acid

Corrosive

2-hydroxybenzoic acid

Irritant

DERRICK ABAITEY

water into it or about 10 minutes. Ethanol should not be put near fire, else it will cause explosion. If swallowed wash out with water and drink two glasses of water, if you are having difficulties in breathing seek for medical attention. If it splits into your eyes tap water into it for about 10 minutes. If it splits on your clothes remove contaminated clothing and if splits on your skin wash the contaminated area with water. If swallowed wash out with water and drink two glasses of water, if you are having difficulties in breathing seek for medical attention. If it splits into your eyes tap water into it for about 10 minutes. If it splits on your clothes remove contaminated clothing and if splits on your skin wash the contaminated area with cold water. If evaporated, take some fresh air, if having difficulty breathing seek for medical attention Wear goggles for eye protection, gloves and lab coat. Wash out with water and drink at least one glass of water, if swallowed, if having difficulty in breathing seek for medical attention. If splits into your eye tap water into it or about 10 minutes Wear goggles for eye

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Extraction Of Salicylic Acid (salicylic acid)

Iodine

Harmful

Methyl 2-hydroxybenzoate, methyl salicylate (oil of wintergreen)

Harmful

Sodium hydroxide solution

Corrosive

DERRICK ABAITEY

protection, gloves and lab coat. If swallowed wash out with water and drink two glasses of water, if you are having difficulties in breathing seek for medical attention. If evaporated, take some fresh air and rest, if having difficulty breathing seek for medical attention and if splits on your skin wash the contaminated area with cold water. Wear goggles, for eye protection, gloves and lab coat. If splits on your skin wash the contaminated are with cold water. Wear goggles, for eye protection, gloves and lab coat. If splits on your skin wash the contaminated are with cold water. Wear goggles for eye protection, gloves and lab coat. Wash out with water and drink at least one glass of water, if swallowed, if having difficulty in breathing seek for medical attention. If splits into your eye tap water into it or about 10 minutes.

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Extraction Of Salicylic Acid

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APPARATUS: • Condenser • Pear shaped flask • Bunsen Burner • Measuring cylinder • Anti- Bumper • 100cm beaker • Small beaker • Glass rod • Ice • Universal paper • Buchner funnel • Watch glass • TLC plates • Cover for the beaker • Dropping tubes • Iodine crystals • Aluminium foil • U.V light source METHOD 1. Into a 50cm pear-shaped flask, put 2cm of oil wintergreen and add 25cm of 2 mol/dm Sodium Hydroxide solution. Do not forget to add anti-bumper. 2. Attach a water condenser to the flask and heat the mixture under reflux for about 30 minutes. The temperature should not be too high. The condensed drop lets should be falling at a rate of about 1 drop per second. 3. Once 30 minutes have passed, turn of the Bunsen burner and allow the mixture to cool. 4. Once the mixture it is already cool down pour it into 100cm beaker, surrounded by cold water. If ice is available you may put some. 5. With the plastic pipette add hydrochloric acid drop by drop, until the mixture turns acidic. Mix it together with a glass rod. 6. Test if the mixture is already acidic, with the Universal Indicator paper. 7. Using a Buchner funnel, filter the product using the vacuum filtration. Was solid with a little cold water and transfer it into a watch glass. 8. Take a few crystals of the product and dissolve them in a minimum of ethanol.

DERRICK ABAITEY

Extraction Of Salicylic Acid

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9. Take a pre-dried thin layer chromatography plate which fit into a small beaker. About 1cm from the bottom of the plate draws a fine pencil baseline. On the line place a small spot of extract from stage 8. On the baseline also put a small spot of a solution of salicylic acid in ethanol. 10. Place some solvent for the chromatography in the beaker to a depth of about 5mm. 11. Place the chromatography plate in the beaker, making sure the solvent is below the pencil line on the plate. 12. Cover the beaker using aluminium foil or watch glass; leave the solvent to rise up. 13. When the solvent has nearly reached the top of the plate, take the chromatogram out of the beaker. Place the plate in a fume cupboard and allow the solvent to evaporate. 14. You can locate the position of the substance on the plate by examining it under UV light. Circle the extracts while under the UV light.

Thiele’s tube: Measuring melting point The Thiele tube is warmed using a micro burner which heats the sidearm elbow. This causes the oil to flow around the tube and past the sample and thermometer bulb by convection, thus warming the sample and thermometer. Determining the melting point: The melting point of a substance is the temperature at which the material changes from a solid to a liquid state. Pure crystalline substances have a clear, sharply defined melting point. During the melting process, all of the energy added to a substance is consumed as heat of fusion, and the temperature remains constant. A pure substance melts at a precisely defined temperature. Determining the melting point is a simple and fast method used in many diverse areas of chemistry to obtain a first impression of the purity of a substance. Method: Set the apparatus as in the picture. To obtain an accurate melting point you must heat the oil at a rate of 1 to 2 degrees per minute as you approach and go through the melting range of the sample. If you heat faster your result will be in error because the bulb of the thermometer will not warm up as quickly as the oil, but your sample will; DERRICK ABAITEY

Extraction Of Salicylic Acid

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Melting point has to be 159 1st = 150°C 2nd = 160°C Range is 150-160, after this range the product got melted. TLC Chromatography is used to separate mixtures of substances into their components. All forms of chromatography work on the same principle. TLC is a simple, quick, and inexpensive procedure that gives the chemist a quick answer as to how many components are in a mixture. TLC is also used to support the identity of a compound in a mixture when the Rf of a compound is compared with the Rf of a known compound (preferably both run on the same TLC plate). A pencil line is drawn near the bottom of the plate and a small drop of a solution of the dye mixture is placed on it. Any labelling on the plate to show the original position of the drop must also be in pencil. If any of this was done in ink, dyes from the ink would also move as the chromatogram developed. When the spot of mixture is dry, the plate is stood in a shallow layer of solvent in a covered beaker. It is important that the solvent level is below the line with the spot on it. The reason for covering the beaker is to make sure that the atmosphere in the beaker is saturated with solvent vapour. To help this, the beaker is often lined with some filter paper soaked in solvent. Saturating the atmosphere in the beaker with vapour stops the solvent from evaporating as it rises up the plate. As the solvent slowly travels up the plate, the different components of the dye mixture travel at different rates and the mixture is separated into different coloured spots.

DERRICK ABAITEY

Extraction Of Salicylic Acid

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Retention Factor (Rf) The retention factor, or Rf, is defined as the distance travelled by the compound divided by the distance travelled by the solvent.

Rf of oil of wintergreen = 3.4/6.1 = 0.55 Rf of Salicylic Acid = 3.5/6.1 = 0.57 After calculating the I can tell from the values that i got that, my product its as pure as the pure salicylic acid. CONCLUSIONS: After carrying out the long process of experiment, I got quiet descent a melting point of 150ºC, for the product, this will determine the melting point gives you an idea of the purity of the product. The two reasons for determining melting point are compound identification and estimation of purity. Merit EVALUATION In this section I will comment about the errors that occurred in the experiment and the improvements that could have been done. Yield: Factors Affecting the Yield (errors) The yield of my product was quiet high; therefore I don’t have much to say about the errors, I tried my best to do this experiment by following the correct procedures. Reduction of yield depends on the experimenter; therefore you can do the best and reduce the errors you come across with. Transfer the product from the Buchner funnel into a watch glass: During process of filtration, the product was left on the Buchner funnel for a long time; therefore it was stacked on it. Hence when I was taking it out, some of it got stuck in the Buchner funnel this was a major source of reducing the yield. Left on the spatula: DERRICK ABAITEY

Extraction Of Salicylic Acid

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I made a mistake when transferring the product form the Buchner funnel, I washed the Spatula, therefore it was a bit wet, which meant the product also got stuck on it as well, this method also went wrong in my experiment. Putting the oil of winter green into the flask: When putting the 2cm³ of the oil of wintergreen into the pear shaped flask, I could have spilled some of the chemical and also I could have left some of it in the quick fit tube when transferring.

Measuring: I lost some of the chemical when measuring it on the weighting balance, since it was not in a good position. Dissolve theme in a minimum of Ethanol: Ethanol evaporates very quickly, therefore when I added the product to it for the first time, as I was mixing it on the watch glass, it got dried up. Therefore I had to do another one again. Filtering the product: When using the vacuum filtration we could have spilled some of the chemical, which would reduce the yield of the product. Adding concentrated HCL: This was added drop-by-drop, until the mixture was acidic; this could affect the yield because I used a glass rod to put small drops of the mixture in to the universal indicator paper but instead of putting small drop I could have put larger drops which will affect the yield of my product. TLC plate: When putting the TLC plate in the beaker, I didn’t put it well therefore my solvent was above the pencil line.

Purity: Factors Affecting the Purity (errors) Contamination: Contamination is very important in this experiment; many things can go wrong and contaminate the product. But in my experiment, these are the processes that I went wrong. Water Contamination: This was when I used the spatula which had water on it; I don’t know what reaction will take place between the product and the water on the spatula. Therefore it might have contaminated my product in the first place. Wash the Apparatus:

DERRICK ABAITEY

Extraction Of Salicylic Acid

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The apparatus has to be washed and dried up, before use. This need to be done 5min before the lesson, other students might have used one of them and didn’t wash it, this will definitely contaminate the product. Left in fume cupboard for days: Since the vacuum filter was not working, we had to leave our various products in the lab for some time. This would have been filtered by the time we come back, hence what might have happened was, and dust moving about in the lab might have contaminated the product. Reflux: During the reflux reaction, many chemicals where added to the chemical without knowing the quantity therefore I added any amount, this made the condensed droplets not fall back drop by drop parsec. It was a different falling back all together; this might also cause the contamination of the product. Distinction How to make minimise the errors and make the yield higher. It’s always important to keep the yield as high as you can to make your experiment a bit accurate. Transfer the product from the Buchner funnel into a watch glass: Since in this process I lost some of my product, next time when the experiment was to be done again, I will make sure I take every bit of the product from the Buchner funnel; if it needs to be measured and subtracted out then I will do that. Left on the spatula: I had to use the spatula anyway; there was nothing I could have done to reduce the amount of product I will lose from using it. The only thing I could have done was to make sure I get most of the product into the watch glass from the spatula. Measuring: During the measurement, I have to use the weighing which is close to me, rather than going far from me. This will make it easier for me to use it all the time and also the amount of product that I might spill off will reduce since I wouldn’t have to carry it around. Dissolve them in a minimum of Ethanol: When I added the product to the ethanol first, it evaporated quickly and I couldn’t use it. I then had to prepare another one again for to be able to use it for the TLC; I will be a bit faster when doing this procedure next time. Filtering the product: The vacuum filtration filters the product very quickly and hence some of the product could have been spilled, therefore I would have to control how the extraction of water with the vacuum filtration happens.

DERRICK ABAITEY

Extraction Of Salicylic Acid

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How to make minimise the errors and make the purity higher. Contamination: The main causes of impurities in such experiments are the contamination of apparatus and chemicals. In this experiment, I had to wash all the equipments that I used in order to reduce the impurities. Water on the spatula: Before using the spatula I realised that there was water on it, which I could have cleaned it with a paper towel or clean it again. This was the only way I could have used to reduce the impurity that it may have cause in my experiment. Wash the Apparatus: As I said in the contamination, when the apparatus are washed, all impurities are taken away, therefore there is assurance of high purity, and therefore all apparatus has to be wash before using. Left in fume cupboard for days: When the product was left in the fume cupboard for about five days; which I believe there has been contamination which has affected the product. This was done because the vacuum filter was not working. I recommend that the next time I do such experiments I will use the vacuum filter which will not take long to obtain my product. Reflux: I added so many chemicals in the reflux process, and I believe there might be some of the chemicals left in the process. This will contaminate the product that I want, after going through all the processes. Putting the oil of winter green into the flask: The flask might have been contaminated before putting the oil of wintergreen into it. This will cause the product to be contaminated after I get it. DERRICK ABAITEY

Extraction Of Salicylic Acid

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TLC plate: You do not have to touch the TLC plate with your hands; this will release amino acids from and come in contact with the plate, which will stop the products from moving. In other words, when you touch the plate you are contaminating it.

DERRICK ABAITEY