Activity No. 6 TESTS FOR THE FUNCTIONAL GROUP PRESENT IN THE ORGANIC COMPOUND Casiño, Jeanne Pearl C. Bachelor of Science in Chemistry Ms. Nova Fe E. Anorico, RCh, MSc May 2021 INTRODUCTION 1.1 Rationale of the Experiment Molecules of organic compounds except that of hydrocarbons can be divided into two parts, a reactive part which is referred to as functional group and a skeleton of carbon atoms called alkyl group. The properties of a compound are largely determined by the functional group. Different compounds having same functional group have similar properties and are classified as family of compounds. Compounds having different functional groups have different properties and belong to different families of compounds. The purpose of this experiment, was to identify the presence of functional groups in the organic compound. Functional groups are specific groupings of atoms within molecules that have their own characteristic properties, regardless of the other atoms present in a molecule. Common examples are alcohols, amines, carboxylic acids, ketones, and ethers (Ashenhuts, 2021). It is very important to absorbed the concept of identifying the functional groups in the organic compound. For it will not just help us progress in the field of organic chemistry, but also being able to able to quickly recognize the most common functional groups, because they are the key structural elements that define how organic molecules react. During the laboratory, different functional groups were asked to obtained. Some of the tests have different methods and approached in indicating the particular groups. Objectives of the Experiment The main objectives of this experiment is to test the presence of functional groups in an organic compound. The experiment addressed the following: 1. To tests the unsaturation of the organic compounds. 2. To tests the presence of alcoholic groups in the organic compound. 3. To tests the presence of phenolic group in the organic compound. 4. To tests the presence of aldehydic and ketonic groups in the organic compound. 5. To tests the presence of carboxylic groups in the organic compound. 6. To tests the presence of the amino group in the organic compound. METHODOLOGY 1. Experimental Set-Up Part A. Test for the Functional Groups Present in an Organic Compound Figure 1. Detection Experiment 1.1 Preparation of Materials and Chemicals In the detection of carbon and hydrogen experiment, a specific materials and chemicals were prepared. The experiment required the following: cupric oxide, anhydrous copper, test tubes, Bunsen burner and tong. Tests for Unsaturation 1.2 Bromine Water Test The unknown compound was taken using spatula and placed in a test tube. A 2mL water from the beaker was transferred to a measuring cylinder. The water was then poured into the test tube and shake. Using the dropper, a 2-3 drops of bromine water was added into the tube and shake. The disappearance of the color red bromine indicates that it was unsaturated. 1.3 Baeyer’s Test The unknown compound was taken using spatula and placed in a test tube. A 2mL water from the beaker was transferred to a measuring cylinder. The water was then poured into the test tube and shake. Using the dropper, a 2-3 drops of KMNO4 solution was added into the tube and shake. The decolorization of the pink color means it is unsaturated. Tests for Alcoholic Groups 1.4 Sodium Methyl Test A 1mL of unknown compound was poured into the measuring cylinder. It was transferred into a test tube. Using a spatula, a small amount of anhydrous calcium sulphate was added and shake. It was then filtered through a funnel into the new tube. A small piece of metal kerosene was taken using forceps, and placed and dried in a filter paper. The dried piece was then added into the test tube with the content. 1.5 Ester Test A 1mL of unknown compound was poured into the measuring cylinder. It was transferred into a test tube. Another measuring cylinder was added with 1mL glacial acetic acid. It was poured into the test tube with the content. Using a dropper, a 2-3 drops of concentrated sulphuric acid was added into the tube. The mixture was then warmed in a water bath for 10 minutes. After that, the mixture was added to a 20 mL cold water and smelled. The alcohol reacts with carboxylic acid in the presence of concentrated sulphuric acid, forming a fruity smelly compound called ester. 1.6 Ceric Ammonium Nitrate Test A 1mL of unknown compound was poured into the measuring cylinder. It was transferred into a test tube. A 2-3 drops of ceric ammonium nitrate were added to the test tube and shake. The alcoholic group reacted with ceric ammonium nitrate giving of a red color. 1.7 Acetyl Chloride Test A 1mL of unknown compound was poured into the measuring cylinder. It was transferred into a test tube. Using spatula, a small amount of anhydrous calcium spatula was added and shake. It was then filtered through a funnel into the another test tube. A 2-3 drops of acetyl chloride were added into the tube with content. A glass rod was dipped in ammonium hydroxide and put near the mouth of the tube. The hydrogen chloride then gives of white fume. 1.8 Iodoform test A 1 ml of the given compound was poured in a clean dry test tube. Then using a dropper, the dilute sodium hydroxide solution was added in the tube until the brown color of iodine was discharged. It was warm gently in a water bath forming a yellow precipitate of iodoform indicating the presence of alcoholic group. Distinction Between Primary, Secondary and Tertiary Alcohols 1.9 Lucas Test A 1 mL dry alcohol was put in three different dry test-tube and added 8-10 drops of Lucas reagent. The test tube for primary alcohol was then heated in the Bunsen burner forming alkyl chloride. Phenols 2.0 Litmus Test A small quantity of unknown liquid was taken using dropper. A 2-3 drop of the given liquid was added on moist blue litmus paper. The color then color to red. 2.1 Ferric Chloride Test A 1 mL of neutral ferric chloride solution was put in clean test tube and 2-3 drops of the liquid compound were added. The color then changed into violet due to the formation of complex. 2.2 Liebermann’s Test A 2-3 crystals of sodium nitrite were put in clean dry test tube and added with 1 g of phenol. It was heated gently for half a minute and allowed to cool down. About 1 mL of concentrated sulphuric acid was added to the tube. A deep blue or deep green color was developed. An amount of water was added carefully, the color then turns red. Then an excess sodium hydroxide solution was added forming a blue or green color. 2.3 Phthalein Dye Test A 0.1 g of organic compound and 0.1 g of phthalic anhydride was put in clean dry test tube and added with 1-2 drops of concentrated H2S04. The content was heated for about 1 minute in an oil bath. It was cooled and poured carefully into the beaker containing 15 mL of dilute sodium hydroxide solution. The appearance of pink, blue, green, red colors indicates the presence of phenolic OH group. Aldehydes and Ketones 2.4 1. 2, 4-Dinitrophenyl Hydrazine Test A small amount the given compound was put in a clean dry test tube, and was added with 2-3 drops of rectified spirit until the compound just dissolved. In a measuring jar a 5 mL of 2, 4dinitrophenyl hydrazine solution was taken and added to the test tube and shake. The yellow color that was formed indicated the presence of aldehydes and ketone. 2.5 Sodium Bisulphite Test A 2 mL of saturated solution of sodium bisulphite was added in a clean test tube. Using spatula an amount of unknown compound was added. The tube was then cork, shake and leave for 15-20 minutes. The formations of crystalline precipitate confirmed the presence of carbonyl group. Test for Aldehydes 2.6 SchifF’s Test Using a dropper, the given compound was taken and poured into clean test-tube and added with 1 mL of SchifF’s reagent. The tube was shake until the color change into pink which means there was a presence of aldehyde group. 2.7 Tollen’s Test A 1 mL of silver nitrate solution was put in clean test-tube and added with 2 mL of dilute NaOH solution. A brown precipitate was formed. Using dropper, a dilute ammonia solution was added drop wise into the test tube until the precipitate dissolves. A 3-4 drops of the given liquid were added to the test tube and warm on a water bath for about 5 minutes. 2.8 Fehling’s Test A 1 mL of Fehling’s solution B was taken in measuring cylinder and poured in a test tube. A 4-5 drops of the given solution were added into the tube and warm in hot water bath for 4-5 minutes. Test for Ketones 2.9 m-Dinitrobenzene test Using a dropper, an amount of given liquid was taken and placed in a clean test tube and added with a small quantity of finely powdered m-dinitrobenzene. A small amount of dilute sodium hydroxide was added and shake. The appearance of violet color indicates the presence of ketonic group. 3.0 Sodium Nitroprusside Test The crystal of sodium nitroprusside was put in a test tube dissolved in distilled water. An amount of the given compound was added to the tube and shake well. It was then added with sodium hydroxide forming a red color. Test for Carboxylic Group 3.1 Sodium Bicarbonate Test Using a dropper, a few drops of the unknown solution was added to the test tube and added with a small quantity of sodium bicarbonate. 3.2 Ester Test A few drops of ethyl alcohol were added to a clean test tube. Another 1-2 drops of concentrated sulphuric acid was added to the same test tube. It was then heated in a water bath and poured in a beaker containing distilled water. 3.3 Litmus Test A small quantity of unknown liquid was taken using dropper. A 2-3 drop of the given liquid was added on moist blue litmus paper. The color then color to red. Test for Amino Groups 3.4 Litmus Test A small quantity of unknown liquid was taken using dropper. A 2-3 drop of the given liquid was added on moist red litmus paper. The color then color to blue. 3.5 Solubility Test An amount of the given compound was taken using spatula and added to the test tube. Then a small quantity of diluted hcl was added. It easily reacts forming a soluble salt. 3.6 Carbylamine Test An amount of solid potassium hydroxide was put in a clean dry test tube and added with 2 mL of ethanol. The test tube was warm until the pallets dissolved. Using a dropper a few drops of chloroform was added into the test tube, and a small amount of the given compound was also added. It was warm gently and produce an offensive smell. 3.7 Azo-Dye Test Using a dropper, a small quantity was transferred into the test tube A. Using another dropper, a small quantity of dilute hcl was added to the tube B. It was also added to test tube A to dissolve the dilute hcl. An amount of sodium nitrite and water was added to the test tube B and shake. Using another spatula, a small quantity of b-napthol was taken and added into the test tube C. Using a dropper, a dilute NaOH was added to tube C.and shake. The test tubes are placed in an ice bath for some time. The content of the test tube B was then fused together with test tube A and so as with the test tube C. 3.8 Nitrous Acid Test A small quantity of sodium nitrite was put in the test tube A along with the distilled water to dissolved. A small quantity of organic compound and concentrated hcl was poured into the test tube B. The test tubes were then placed in an ice bath and cooled. The two were mix together about 5 ml water in a test-tube and cool in ice bath and cool down. The results were then recorded. 3.9 Hinsberg Test Using a dropper, an amount of the given NaoH solution which was 25% was added into the clean test tubes A, B and C. A small quantity of water was added to the test tubes. Using another dropper, a quantity of benzene sulphonyl chloride was added to the three test tubes and shake. The test tubes were placed in a beaker containing distilled water. 4.0 Schematic Diagram Test for the Functional Groups Test for Alcoholic Groups - - Bromine water test, fused together the unknown compound in the test tube & add bromine water. Braeyer’s test, fused together the unknown compound in the test tube & add KMNO4 sol’n. Test for Phenols Aldehydes and Ketones - Litmus test, add 2-3 - Hydrazine test, add 2-3 drops drops of unknown of rectified spirit and dinitrophenyl liquid. hydrazine in the test tube and shake. – Ferric test, fused - Sodium bisulphite test, fused 2mL FeCl3 and given of NaHSO3 and unknown compound. Liquid in test tube. Shake and leave for 15-20 mins. – Liebermann’s test, dry NaNO2, heat and cool. Add H2SO4. Phthalein test, fused compound, phthalic & con. H2SO4 in a test tube. Test for Carboxylic Groups Test for Aldehydes - - - Test for Ketones SchifF’s test, add - NaHCO3 test, mix an amount - m-dinitrobenze test, compound & schifF’s of unknown sol’n & NaHCO3. fuse liquid, nitroprusside reagent in a test tube - Ester test, add few drops of ethyl & NaOH in a test tube & shake. alcohol & con. H2SO4 in the tube and shake. Tollen’s test, fuse together heat and pour in a beaker. – Sodium nitroprusside the liquid, NaNO3, NaOH & - Litmus test, add 2-3 drops test, dissolve the crystal ammonia sol’n in test tube of unknown liquid in litmus. in water add given and bath for 5 mins. paper. Compound and NaOH. Fehling’s test, add 1mL Fehling sol’n and given liquid in the tube and warm in hot bath for 5mins. Each tests have their own processes Test for Amino Groups make sure you do it correctly. END OF THE EXPERIMENT Part B. Detection of Elements Lassaigne’s Test Figure 3. Lassaigne’s Extraction Experiment 1.4 Preparation of Materials and Chemicals In the detection of elements experiment, a specific materials and chemicals were prepared. The experiment required the following: cupric oxide, anhydrous copper, test tubes, Bunsen burner and tong. 1.5 Preparation of Lassaigne’s Extract A small piece of sodium metal was taken with the use of forceps and place in a filter paper. It was dried by placing another layer of filter paper on top of it. The sodium metal was then transferred into a fusion tube. Using a crucible tong, it was heated in the Bunsen burner for the metal to melt. Using a small spatula, a small amount of organic compound was taken and added into the tube. The tube is heated again until the color becomes red. A distilled water was poured into the china dish where the tube was placed and crashed with a stirring rod. The process was repeated 2-3 times. The china dish was then heated at a boiling point and removed until the liquid reduced up to 1/3 of it. The liquid was poured into a funnel with a filter paper that is attached to a clamp unto the test tube and labeled as lassaignes extract. 1.6 Detection of Nitrogen A small amount of lasssaigne’s extract was taken using a dropper and poured into a clean test tube. Using another dropper, a small amount of ferrous sulfate solution was taken and added into the test tube containing the extract. The test tube was then heated in the Bunsen burner. It was placed back in the test tube rack. With the use of another dropper an amount of ferric chloride was taken and added into the same test tube with the content. An amount of concentrated hcl was then taken using dropper and was added to the same test tube. The color of the liquid turned into blue. 1.7 Sodium Nitroprusside Test An amount of lassaigne’s extract was taken using a dropper and placed in a test tube. With the use of another dropper again, a small amount of sodium nitroprusside was taken and added into the test tube. After some reaction, a purple color then showed up. 1.8 Lead Acetate Test A small amount of lassaigne’s extract was taken using a dropper and placed in a test tube. Using a dropper, a quantity of acetic acid was added to the test tube. Using another dropper, an amount of lead acetate was taken and added into the test tube containing the content. Upon reaction, sodium sulfide was formed. 1.9 Silver Nitrate Test A small amount of lassaigne’s extract was taken using a dropper and placed in a test tube. Using a dropper, an amount of concentrated nitric acid acid was added to the test tube. The test tube was then heated in the Bunsen burner for quite some time. After cooling, a quantity of silver nitrate was added into the same test tube. In the presence of chloride, the precipitate formed a white color. In bromine, a pale yellow precipitate was noticed. In iodine yellow color precipitate formed. Using another dropper, an amount of ammonium hydroxide was taken and added into the test tubes with white, pale yellow and yellow precipitate and was shake well. Upon reaction, sodium sulfide was formed. 2.0 Carbon Disulphide Test A small amount of lassaigne’s extract was taken using a dropper and placed in a test tube. Using another dropper, an amount of dilute hcl was taken and added to the test tube. With another dropper, a quantity of carbon disulphide was taken and added into the test tube containing the content. It formed a separate layer above the lassaignes extract. A chlorine water was then taken using dropper and poured into the test tube and shake well to dissolved. RESULTS AND ANALYSIS The following data shown in Table 1.1 and Table 1.2 was obtained from the results, after the experiment for the detection of organic elements. Table 1.1 Results in the Detection of Carbon and Hydrogen Organic Compound mixed with Cupric oxide Presence of Carbon Carbon dioxide gas Presence of Hydrogen Water vapor Result Milky Blue precipitate Table 1.1 shows the result in the detection of carbon and hydrogen. You will see that after the detection process of carbon dioxide it became milky which basically says it undergoes a reaction. That is because of the carbon dioxide gas passing through a limewater, and it turns out to be milky due to the formation of calcium carbonate. Lime (calcium oxide) is a white solid with strongly basic properties. Lime reacts readily with water to produce slaked lime, which is the chemical compound calcium hydroxide (Lime, 2021). A considerable amount of heat energy is released during this reaction. On the other hand, in the presence of hydrogen a water vapor was formed. Water vapor is the gaseous phase of water, but as it goes a reaction upon passing through white anhydrous the color became blue. According to Nagi, if a drop of water was poured over anhydrous copper sulphate then then some of the water molecules will form coordinate bonds with Cu2+ ion and some of the water molecules will be immediately taken as water of crystallization with the help of hydrogen bonds. As soon as the water was coordinated the color blue appeared. Table 1.2 Results in the Detection of Organic Elements Organic Elements Results Ferrous sulfate and Ferric Chloride Sodium Nitroprusside Nitrogen Sodium thionitroprusside Lassaigne’s Extract Acetic acid and Lead Acetate Lead Sulfide Nitric acid and Silver Nitrate Chlorine, Bromine and Iodine Bromine and Iodine Dilute HCl Disulphide and Carbon Table 1.2 shows the result in the detection of organic elements through lassaigne’s test. In this experiment, all of the compounds were reacted with lassaigne’s extract. Lassaigne’s extract was obtained by fusing metallic sodium with an organic compound and heated gently. The test for nitrogen involved boiling and sodium fusion with ferrous sulfate and ferric chloride. Which lead to the development of a blue precipitate which indicates the presence of nitrogen. As for the sodium nitroprusside and lead sulfide both processed were the same, they were fused with their respective compounds together with the lassaigne’s extract and the color precipitates. For sodium thionitroprusside a purple color appeared and a black color showed up for lead sulfide. For halogens it was heated with excess nitric acid to ensure complete destruction of sodium carbonate. Since there was a presence of cyanide and sulfide ions they are removed by boiling it in an acid solution. During the preparation of lassaigne's extract, chlorine reacts with sodium to form sodium chloride giving us a white precipitate of silver chloride with silver nitrate, which is soluble in ammonium hydroxide. Sodium bromide formed a pale yellow precipitate of silver bromide, which is also soluble in ammonium hydroxide. The fusion of lassaigne’s extract and silver nitrate formed a yellow precipitate of silver iodide, wherein somehow different to the two for it is insoluble in ammonium hydroxide. In the detection of carbon disulphide, the layers were separated into two but sodium bromide and sodium iodide were treated with chlorine water, in order for the the bromide and iodide to oxidize to the corresponding halogens. The halogen dissolves in carbon disulphide. Bromine imparts orange colour and iodine imparts violet colour in carbon disulphide layer (Olabs, 2021). REFERENCES https://www.learncbse.in/tests-for-the-functional-groups-present-in-organic-compounds/ https://www.learncbse.in/tests-for-the-functional-groups-present-in-organic-compounds/ http://amrita.olabs.edu.in/?brch=8&cnt=1&sim=141&sub=73 https://courses.lumenlearning.com/suny-mcc-organicchemistry/chapter/functionalgroups/#:~:text=The%20concept%20of%20functional%20groups%20is%20a%20very%20impor tant%20one.&text=As%20we%20progress%20in%20our,define%20how%20organic%20molecu les%20react.
