A)AYC R RAYS YR(7AN;C CAA1AA Ax..Y Fc J t )Vj O O Ri EXPERIMENTS IN ORGANIC CHEMISTRY A LABORATORY MANUAL DESIGNED TO ACCOMPANY OUTLINES OF ORGANIC CHEMISTRY BY F. J. MOORE, PhD. ASSOCIATE PROFESSOR OF ORGANIC CHEMISTRY IN THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY FIRST FI^'TI FIRST THOUSAND NEW YORK JOHN WILEY & SONS London: CHAPMAN & HALL, Limited 1911 Copyright, 1911 BY F. J. MOORE Stanhope Ipress F. H. GILSON COMPANY BOSTON. U.S.A. PREFACE. In the preparation of the following pages, the same student has been kept in mind for whom the author's " Outlines of Organic Chemistry" was written, viz., one who does not expect to become an organic chemist and who may not pur- sue that study further. Such a student need not be able to apply analytical tests with the highest skill, nor, in the prep- aration of compounds, is it essential that he should always secure either maximum purity of product or a maximum yield. It is, rather, desirable that in the time at his disposal he should come into contact with as many organic com- pounds as is practicable, learn their properties at first hand, and study those of their reactions which have the greatest general interest. This point of view has been kept in mind in the compilation of the following experiments. These have been collected from a variety of sources, tested in the labora- tory, and then turned over to a class of engineering students at the Massachusetts Institute of Technology. These men, though beginners in Organic Chemistry, obtained, with es- sential unanimity, the results expected. The experiments have been divided - somewhat arbitra- rily- into fifteen exercises, of which it is believed that each will furnish ample material for three hours' consecutive work. Any other subdivision will be found entirely practicable. The page references following the titles of the experiments are to the textbook already mentioned, and are intended to keep the practice in close touch with the theory. The author is well aware that time and experience with a large number of students are necessary before directions for III IV PREFACE laboratory experiments can assume their final form. He will, therefore, be especially grateful to any who will suggest improvements either in the experiments themselves or in the phraseology of the directions. F. J. MOORE. Massachusetts Institute of Technology, May, 1911. CONTENTS. EXERCISE I. PAGE Teat for Nitrogen in an Organic Substance. - Tests for Halogens. - For Sulphur 1 EXERCISE II. Ethyl Alcohol, Preparation by Fermentation. -Absolute Alcohol. - Preparation of Methane. - Paraffin Series, Solubilities. - Flash-point Test 4 EXERCISE III. Ethyl Alcohol, Iodoform Test. - Absolute Alcohol (continued). - Preparation by Fermentation (continued). - Behavior of Miscible Liquids on Distillation. - Determination of Alcohol in an Aqueous Solution 6 EXERCISE IV. Preparation of Ethyl Bromide. - Behavior of Alkyl Halides with Silver Nitrate 8 EXERCISE V. Formic Acid. - Acetic Acid 9 EXERCISE VI. Acetyl Chloride. - Acetic Anhydride 11 EXERCISE VII Preparation of Ethyl Acetate. - Saponification 12 V VI CONTENTS EXERCISE VIII. page Aldehydes. - Acetone 14 EXERCISE IX. Methylamine, Preparation from Acetamide. -Reaction with Nitrous Acid. - Oxalic Acid from Sugar 15 EXERCISE X. Preparation and Properties of Ethylene. - Oxidation of Amylene. - Acetylene 16 EXERCISE XI. The Constituents of Milk. - Saponification of Butter. - Acrolein from Glycerin 18 EXERCISE XII. The Inversion of Sugar. - Cellulose. - Urea. - Potassium Xan- thate. - Ammonium Sulphocyanate 19 EXERCISE XIII. Nitrobenzene. - Aniline 21 EXERCISE XIV. Aniline (continued).-Phenol 23 EXERCISE XV. Parafuchsine. - Picric Acid. - Methyl Orange. - Phenolphthal- ein. - Fluorescein. - Indigo. - Alizarin 25 EXPERIMENTS IN ORGANIC CHEMISTRY EXERCISE I. TO DETECT NITROGEN IN AN ORGANIC SUBSTANCE. Pages 11, 12. By means of a clamp fix a small weighing-tube in a ver- tical position and introduce into it a small piece of freshly trimmed sodium not larger than a pea. Heat the tube cautiously from below by means of a flame held in the hand, until the sodium has melted and commenced to vaporize. Then sprinkle into the tube a half-dozen crystals of the substance to be tested, and continue the heating for a half- minute longer. When the melt has cooled to the tempera- ture of the room, add 1 c.c. of alcohol, and wait till the bubbling which at first takes place has ceased. Then add water very cautiously and finally pour the contents of the weighing-tube into a small evaporating-dish, washing out the tube with more water until the total volume of water amoun s to about 20 c.c. Caution.- Small portions of sodium are sometimes left unattacked by the alcohol, and when these come in contact with water slight explosions result. It is therefore necessary to work cautiously and to take pains that no pieces of sodium are thus thrown into the face or eyes. Add 2 or 3 drops of dilute sodium hydroxide solution to the liquid in the evaporating-dish, and filter. The filtrate should be clear and colorless. To a portion of it in a test- 1 2 EXPERIMENTS IN ORGANIC CHEMISTRY tube add 2 drops of a ferrous sulphate solution, and warm gently for about a minute, shaking from time to time in order to promote the oxidation of some of the ferrous salt by the air. When brown films of ferric hydroxide begin to appear upon the sides of the tube, cool thoroughly and add enough dilute sulphuric acid, a drop at a time, to dissolve the hydroxides of iron. Avoid any excess of acid. If nitrogen was present in the original substance, a precipitate of Prussian blue should remain undissolved. If there is any uncertainty about the test, allow the solution to stand a half-hour and filter. Small precipitates of Prussian blue are oftentimes to be detected only in this way. Write answers to the following questions in the note- book : - 1. What is accomplished by heating the nitrogenous com- pound with sodium? 2. Why is sodium hydroxide solution added to the solu- tion of the melt? 3. What is accomplished by the digestion with ferrous sulphate? 4. Why is oxidation of the iron salt permitted? 5. Write all equations involved. TESTS FOR HALOGENS. Pages 11, 12. A General Test. - Wrap the end of a platinum wire about a small piece of copper oxide. Hold the latter in the edge of the flame of a Bunsen burner until any green tint has disappeared. Then dip the copper oxide into a solution containing a halogen and again introduce it into the flame. Explain the phenomena observed. If this test yields a posi- tive or doubtful result, try the following: - Decompose a substance containing halogen by means of sodium in the same manner as described in the test for TESTS FOR SULPHUR 3 nitrogen. In this case make the solution just acid with nitric acid, bring to a boil, and allow to cool. Divide the solution into three parts. To one add a few drops of silver nitrate solution. To the second add half a cubic centi- meter of carbon bisulphide and shake, then add 2 drops of chlorine water and shake again. To the third portion add a little carbon bisulphide and potassium nitrate solution and shake. Write answers to the following questions: - 1. What products are formed by the action of sodium upon the substance? 2. Why is the solution acidified and boiled? 3. How much (and how little) does the formation of a precipitate with silver nitrate indicate? 4. What is the action of chlorine water upon a solution of the sodium halides? Of potassium nitrite? 5. What is the use of the carbon bisulphide? TESTS FOR SULPHUR. Page 12 Decompose a little of the substance with sodium in the same manner as in the test for nitrogen. Divide the result- ing solution into three parts. To the first add 3 drops of a 1 per cent solution of sodium nitroprusside. To the second add 1 c.c. of a solution prepared by adding sodium hydroxide to a solution of lead acetate until the precipitate first formed just redissolves. Give the chemistry of the latter test. To the third portion add half a cubic centimeter of silver nitrate solution. Write all reactions involved. 4 EXPERIMENTS IN ORGANIC CHEMISTRY EXERCISE II. PREPARATION OF ALCOHOL BY FERMENTATION. Pages 63, 167-170, 175. Dissolve 20 grams of commercial glucose in 100 c.c. of water and add 10 c.c. of a nutrient solution.1 Place the solution in a flask which it will fill almost to the top, and which is provided with a Bunsen valve.2 Finally macerate half a yeast cake with water, and add the resulting paste to the solution. Stopper the flask tightly and allow the mix- ture to stand until the next exercise. ABSOLUTE ALCOHOL. Pages 61, 62. Put 50 c.c. of 95 per cent alcohol in a perfectly dry flask. Add 20 grams of lime in small lumps and tightly stopper the flask. Allow the mixture to stand until the next exercise. PREPARATION OF METHANE. Page 37. Dehydrate 3 grams of crystalline sodium acetate by heat- ing gently in an evaporating-dish with a free flame.3 Mix 1 The yeast requires the presence of certain inorganic salts for its nutriment. A suitable solution may be prepared by dissolving 10 grams each of potassium nitrate, magnesium chloride, calcium nitrate, and potassium phosphate in water and diluting to one liter. 2 A Bunsen valve consists of a short piece of glass tubing passing through the cork and connected at its outer end with a piece of small rubber tubing about 2 inches long, whose other end is closed by means of a piece of glass rod. In the rubber tubing is a longitudinal slit about half an inch long which permits the egress but not the entrance of gases. 3 When crystalline sodium acetate is heated, it first dissolves in its water of crystallization. When this has been expelled, the salt solidifies but fuses on further heating. Finally decomposition takes place into sodium carbonate and acetone. In this experiment, heating should be stopped at the "second fusion." THE PARAFFIN SERIES - SOLUBILITIES 5 intimately in a mortar 2 grams of the anhydrous sodium acetate with 4 grams of dry soda lime. Fill a test-tube one- third full of the mixture, attach a cork and delivery-tube leading to a pneumatic trough, and heat with a smoky flame Collect any gases evolved in test-tubes. Test these samples with a flame for their ability to burn and to support combustion. In doing this take care to keep the test-tubes wrapped in a towel, as, if the methane contained air, an explosion might result of sufficient violence to shatter the tube. Mention three other methods for the preparation of methane. Write all equations. THE PARAFFIN SERIES - SOLUBILITIES. Pages 44, 45, 51-53. Place in a test-tube about 0.25 gram of paraffin and pour over this about 5 c.c. of concentrated sulphuric acid and warm the whole in a beaker of boiling water for three min- utes. Finally cool under the tap. Is any evolution of heat noted when the paraffin and sulphuric acid are mixed? any change of color? What hap- pens on heating? on cooling? Repeat the same experiment, using in turn concentrated hydrochloric acid, concentrated nitric acid, and sodium hydroxide. Test the solubility of 0.25 gram of paraffin in 10 c.c. of ether, alcohol, and ligroin. When warming any of these mixtures, do so by means of a beaker containing hot water. Have no flames burning in the vicinity. Mix ligroin with water, with alcohol. What is observed? Mix 2 c.c. of ligroin with ether and then add 10 c.c. of alcohol to the mixture. Shake 2 c.c. of paraffin oil with 5 c.c. of ligroin, of ether, of alcohol, of water. 6 EXPERIMENTS IN ORGANIC CHEMISTRY FLASH-POINT TEST FOR OILS. Pages 54, 55. In a piece of pasteboard cut a hole large enough to admit the body but not the rim of a No. 1 beaker, and place the pasteboard with the beaker suspended in it across the top of a No. 5 beaker. Or suspend the small beaker in the large one by means of a wire around the rim. Fill the outer beaker with water until it covers about two-thirds of the inner one. Then fill the small beaker with kerosene to within a half- inch of its top, and suspend a thermometer in the oil. Place the whole apparatus upon a wire gauze and heat from below by means of a small flame so that the thermometer rises no faster than 2° per minute. Meanwhile draw out a piece of glass tubing so as to make a small orifice about the size of a blow-pipe tip, or the latter itself might be used. Attach this by a rubber tube to the gas tap so as to give a small flame. Pass this flame evenly across the top of the small beaker, taking care that it does not touch the oil. Repeat this as often as the thermometer rises 1°. Note and record as the flash-point of the oil, the temperature at which a transitory "flash" is first seen. Do not continue the heating beyond this point, as a disagreeable fire might result. EXERCISE III. IODOFORM TEST FOR ETHYL ALCOHOL. Pages 113, 114. To 2 c.c. of a solution made by mixing 1 part of alcohol with 5 parts of water add 2 c.c. of a 3 per cent solution of iodine in potassium iodide and 8 drops of a 3 per cent sodium hydroxide solution. After shaking, warm the mixture for a few seconds in a beaker of water heated to about 70°. The amount of alkali added should not be sufficient to BEHAVIOR OF MISCIBLE LIQUIDS ON DISTILLATION 7 completely decolorize the iodine solution. If no precipi- tate appears, scratch the walls of the test-tube with a glass rod. ABSOLUTE ALCOHOL (Continued). Distill off the alcohol which has been dried over lime (see Exercise II), using a perfectly dry condenser and receiver. Test the distillate for water with anhydrous copper sulphate, noting the time necessary for the appearance of a blue color- ation. Prepare the anhydrous copper sulphate by heating 2 to 3 grams of the hydrated salt carefully in an evaporat- ing-dish until it turns white. Avoid overheating, since this causes the formation of black copper oxide. It is best to grind the copper sulphate in a mortar before heating. ALCOHOL BY FERMENTATION (Continued). Distill off 5 c.c. of the fermented sugar solution (see Exercise II) and make the iodoform test for alcohol in the distillate. BEHAVIOR OF MISCIBLE LIQUIDS ON DISTILLATION. Pages 7, 8, 61. To 50 c.c. of alcohol add enough water to make the volume of the resulting mixture 100 c.c. Put the mixture into a 200 c.c. distilling-flask, fitted with a condenser. Use a graduate as a receiver, and distill rapidly with a free flame until only a sufficient residue remains in the flask to avoid breaking the glass. Record in the notebook the quantities of liquid which distill over between each successive 2° of temperature. It is very essential that the gas flame used should not be large, and that it should not touch the flask above the surface of the liquid; otherwise the vapors are superheated and the thermometer does not record the boiling-point of 8 EXPERIMENTS IN ORGANIC CHEMISTRY the distillate. For a similar reason the liquid must be kept boiling vigorously all the time; otherwise the vapors do not reach the thermometer. Apply the theory of fractional distillation to the results obtained. Give an outline of this theory in the notebook. What would have been the composition of the liquids ob- tained by a complete fractionation of the mixture in question? DETERMINATION OF THE QUANTITY OF ALCOHOL IN AN AQUEOUS SOLUTION. Page 62. In the same distilling apparatus used in the previous ex- periment place 100 c.c. of the solution marked "For Deter- mination of Alcohol Content." Distill until 50 c.c. or more have come over. Make the distillate up to the original volume with distilled water. Determine the specific gravity with a hydrometer, and from this the volume-percentage of alcohol in the original mixture. Define percentage by weight and percentage by volume. Why cannot the percentage of alcohol be determined directly by the hydrometer without distillation in ordinary practice? What fundamental assumption is involved in the method? EXERCISE IV. PREPARATION OF ETHYL BROMIDE. Pages 72-74. In a 750 c.c. flask mix with constant shaking 100 grams of concentrated sulphuric acid and 45 grams of alcohol. Cool to room-temperature and add, with constant stirring, 35 grams of water and finally 50 grams of potassium bromide. Place the flask upon a wire gauze, attach a condenser, and distill rapidly, but taking pains that the liquid does not FORMIC ACID 9 foam excessively. As a receiver use an Erlenmeyer flask almost full of cold water, into which the end of the con- denser should dip. Place the flask in a dish large enough to catch any water which may run over. Stop the distillation when no more oil drops come over. Pour off most of the supernatant water and wash the oil with dilute sodium carbonate solution until neutral. Finally separate the oil from the water in a separatory funnel, run- ning the oil into a 50 c.c. distilling-flask. Add a half-dozen small pieces of calcium chloride, agitate, and finally distill again through a dry condenser, leaving the calcium chloride in the flask. Note the boiling-point of the liquid. In dis- tilling use a beaker of hot water rather than a free flame. The part which should be collected boils from 34° to 40°. Put the product in the bottle provided. Add a few drops of silver nitrate solution to 1 c.c. of each of the following substances: methyl iodide, ethyl iodide, ethyl bromide, chloroform. Note all differences of behavior. How would the halogen compounds of potassium, sodium, or calcium have behaved toward silver nitrate? BEHAVIOR OF THE ALKYL HALIDES TOWARD SILVER NITRATE. EXERCISE V. FORMIC ACID. Pages 86, 87. Mix about 100 grams of glycerin with 20 grams of crys- tallized oxalic acid. Place the mixture in a 200 c.c. flask fitted with a condenser and distill with a small flame until about 10 c.c. have come over. Allow the mixture to cool somewhat and then add 10 grams more of oxalic acid and distill until 5 c.c. more have come over. Test the distillate with litmus paper. 10 EXPERIMENTS IN ORGANIC CHEMISTRY To 5 c.c. of the distillate add 0.5 gram of mercuric oxide and shake thoroughly. Warm the mixture gently by dip- ping the test-tube into warm water for a moment. Finally filter and bring the filtrate to a boil. This is a delicate test for formic acid, and illustrates its reducing action. Write the reactions involved. To a second 5 c.c. portion of the distillate add a little potassium permanganate solution and acidify with sulphuric acid. Treat the remainder of the distillate as follows: Bring the liquid to a boil and stir into it small portions of lead carbonate until no further effervescence occurs. (Not more than 1 gram should be required.) Filter boiling hot. On cooling fine white crystals of lead formate should appear. ACETIC ACID. Pages 88, 89. Heat 1 c.c. of glacial acetic acid to boiling in a test-tube. Note the inflammability of the vapors. Repeat the tests with mercuric oxide and potassium per- manganate, using acetic instead of formic acid. Immerse a test-tube containing 5 c.c. of glacial acetic acid in ice-water. Scratch the walls with a glass rod to promote crystallization. When the mass is about half frozen, insert a thermometer and note the melting-point of the acetic acid. Pure glacial acetic acid melts at 16.5°. For highly con- centrated acids it is approximately true that each per cent of water lowers the melting-point about 1°. Test the miscibility of glacial acetic acid with alcohol, ether, chloroform, and ligroin. To a dilute solution of sodium acetate add a few drops of ferric chloride solution. Note the color produced, and then heat to boiling. ACETYL CHLORIDE 11 EXERCISE VI. ACETYL CHLORIDE. Pages 91-93. Arrange an apparatus for distillation as follows: Using a 150 c.c. distilling-flask, connect it with a condenser, and as a receiver use a filter-bottle attached air-tight by means of a cork to the lower end of the condenser. To the side- arm of the filter-bottle attach a straight calcium chloride tube, and to the other end of the latter a piece of delivery tubing bent down in such a way that the end almost touches the surface of a solution of caustic soda contained in a beaker. This tube must under no circumstances dip into the liquid. Close the neck of the distilling-flask by a cork through which passes the stem of a separatory funnel. All parts of the apparatus should be thoroughly dry, all corks well rolled, and all connections air-tight. Test these before going on with the experiment. Write in the notebook the reason for each detail of the apparatus prescribed. Surround the flask with cold water and introduce into it 50 grams of glacial acetic acid. Then add slowly through the separatory funnel 40 grams of phosphorus trichloride. Be sure to add this slowly enough so that no marked rise in temperature occurs. Now heat the water which surrounds the distilling-flask to a temperature of 40° to 50° until the mixture inside has separated into two layers. Finally bring the water to boiling and heat until no more liquid distills. After the completion of the reaction, before removing the receiver, cool the distilling-flask by replacing the water- bath with cold water; otherwise the vapors liberated when the flask is opened may cause great annoyance. With the product try the following experiments: - Add about one-half a cubic centimeter drop by drop to 5 c.c. of cold water in a test-tube, testing the resulting mix- 12 EXPERIMENTS IN ORGANIC CHEMISTRY ture with litmus paper. Write the equation for the reaction which takes place. In a similar manner mix about 1 c.c. of the product with an equal quantity of alcohol, keeping as cool as possible. Now make alkaline with a little sodium hydroxide solution and note the odor of the product. Write the equation for the reaction. ACETIC ANHYDRIDE. Pages 93-95. Place in a 100 c.c. retort 25 grams of finely pulverized anhydrous sodium acetate. Connect this with a condenser and receiver exactly similar to that employed in the last experiment. Close the tubulus of the retort with a cork through which passes the stem of a separatory funnel, and introduce slowly through the latter the remainder of the acetyl chloride just prepared. When all has been added, replace the dropping-funnel by a simple cork and distill rapidly, using a large smoky flame, as long as any distillate is obtained. If time permits, subject the product to a second distillation with about 5 grams of anhydrous sodium acetate, using a fractionating flask and a small non-luminous flame. Collect what passes over above 125°, and treat portions of it with water and alcohol as in the case of the acetyl chloride. If there is not sufficient time to redistill, carry out these tests with the crude product. EXERCISE VII. ETHYL ACETATE. Pages 94-100. Mix 50 c.c. of alcohol with 50 c.c. of glacial acetic acid and add slowly 50 c.c. of concentrated sulphuric acid with constant shaking. Pour this mixture into a 200 c.c. dis- tilling-flask and connect with a condenser and receiver. SAPONIFICATION OF ETHYL ACETATE 13 Now close the flask with a stopper through which passes a thermometer reaching down into the liquid. Heat slowly on a wire gauze. Collect separately that portion of the distillate which goes over between 140° and 160°. Agitate this solution in an open flask with dilute sodium carbonate solution until neutral to litmus, then separate the oil in a separatory funnel. Place the product in the bottle provided. SAPONIFICATION OF ETHYL ACETATE. Pages 95-100, 142-144. By means of a burette1 introduce into a small round- bottomed flask about 2 c.c. of pure ethyl acetate, recording the exact amount taken in the notebook. Add 40 c.c. of standard potassium hydroxide solution (about normal), also from a burette. Boil with a return condenser for a half- hour on a wire gauze, and on cooling add from a burette enough of the standard hydrochloric acid solution to make the solution neutral to phenolphthalein. From the data obtained calculate the saponification number of ethyl acetate, comparing it with that theoretically obtained from the formula. The specific gravity of ethyl acetate is 0.83. For the purposes of this experiment the saponification number will be defined as the number of milligrams of po- tassium hydroxide necessary to saponify 1 gram of ethyl acetate. The determination of the saponification number is frequently necessary in oil analysis. 1 More accurate results can, of course, be obtained by weighing the ethyl acetate, but for a class of beginners the weighing of so volatile a substance presents difficulties of its own. 14 EXPERIMENTS IN ORGANIC CHEMISTRY EXERCISE VIII. ALDEHYDES. Pages 103-111. Place in a test-tube 5 c.c. of methyl alcohol mixed with 3 c.c. of water. Now take a piece of thin copper wire about a foot long and twist one end of it into a spiral by winding about a pencil. Heat the spiral to redness for a minute in a gas flame and then plunge it into the alcohol solution. Remove the spiral, and if the vapor takes fire extinguish it by closing the mouth of the tube. It is well to repeat this process in order to insure the oxidation of a sufficient quan- tity of alcohol. First note the odor of the escaping vapor, and then divide the contents of the test-tube into three portions, to which apply the following tests: - To the first part add 1 drop of resorcinol solution (2 per cent). Pour the mixture down the side of a test-tube con- taining 5 c.c. of concentrated sulphuric acid. Note the color of the ring which is formed on standing. To the second portion of the original solution add a mix- ture of 1 c.c. of a 5 per cent ammoniacal silver nitrate solu- tion and 1 c.c. of a 5 per cent sodium hydroxide solution. Heat slightly if necessary. Caution.-Do not allow any mixture containing ammonia, silver nitrate, and sodium hydroxide to stand more than a few minutes, as a dangerously explosive substance is apt to form. To the third portion add a few drops of a fuchsine-sulphur- ous-acid solution. Repeat all the above experiments, using ethyl alcohol instead of methyl alcohol. Evaporate 10 c.c. of formalin solution to dryness on a water-bath. What is the residue? REACTION WITH NITROUS ACID 15 In a 100 c.c. distilling-flask place 10 c.c. of ethyl alcohol^ 50 c.c. of dilute sulphuric acid (1 : 10), and 20 c.c. of a 10 per cent potassium bichromate solution. Attach to a con- denser and distill cautiously. See that the end of the con- denser dips just under the surface of about 10 c.c. of cold water. Distill until about 10 c.c. have passed over, and with the distillate try all the tests described in the first part of the exercise. ACETONE. Pages 111-113. Distill 25 grams of calcium acetate in a small retort at- tached to a condenser, using a free smoky flame. When about 10 c.c. have distilled over, stop the action and shake the distillate with sodium bisulphite solution, frequently scratching the walls of the test-tube, and note the precipitate formed. EXERCISE IX. METHYLAMINE FROM ACETAMIDE. Pages 116-119. Under a hood dissolve 1 c.c. of bromine in 5 c.c. of cold concentrated sodium hydroxide (1 : 2). Add about 1 gram of acetamide and heat gradually to boiling. Note the odor of the escaping vapors and test their inflammability. Hold a stopper moistened with hydrochloric acid near the mouth of the tube. Write all reactions involved. Mix a little methylamine hydrochloride with dilute sodium hydroxide and warm the solution. Make tests similar to the foregoing. REACTION WITH NITROUS ACID. Pages 119, 120. Place 20 c.c. of dilute acetic acid in a 50 c.c. distilling- flask, closing the mouth of the flask with a stopper through which passes a thistle-tube reaching nearly to the bottom 16 EXPERIMENTS IN ORGANIC CHEMISTRY of the flask. Connect the side-neck of the flask to a wash- bottle made from a test-tube with a double-bore stopper. Have the test-tube two-thirds full of an alcoholic solution of sodium hydroxide and have its exit tube lead to a pneu- matic trough. See that all joints are tight. Now dissolve 1 gram of methylamine hydrochloride in a very little water, also 1 gram of sodium nitrite in a similar volume of water. Mix the solutions and pour the mixture into the distilling-flask through the thistle-tube. Add 10 c.c. of dilute sulphuric acid and warm slowly if necessary as long as a gas is evolved. Collect the latter in test-tubes over water. Test the gas for nitrogen with a glowing splinter. Now connect the distilling-flask with a condenser and dis- till off about 10 c.c. into a test-tube. Test the distillate for methyl alcohol by means of the glowing copper spiral and resorcinol solution in the same way as in Exercise VIII. OXALIC ACID FROM SUGAR. Page 137. In an evaporating-dish under a hood cover 10 grams of cane-sugar with 100 c.c. of commercial nitric acid (sp. gr. 1.24). Heat gently until the reaction begins. It will then proceed of itself with some violence. When the reaction has abated, evaporate to about 20 c.c. and allow to stand. Oxalic acid crystallizes on cooling. EXERCISE X. PREPARATION AND PROPERTIES OF ETHYLENE. Pages 125-129. Set up an apparatus consisting of a 500 c.c. flask, two wash-bottles prepared from large test-tubes, and a pneu- matic trough, making connections as follows: Fit the flask with a tube leading just through the stopper of the first wash- ACETYLENE 17 bottle. From the bottom of the latter lead a tube to the bottom of the second. From just below the stopper of the second wash-bottle lead a tube to the pneumatic trough. This arrangement is necessary in order to avoid back-suc- tion of the liquid from the wash-bottle into the generating flask. When the apparatus has been set up and the connec- tions tested and found air-tight, fill the second wash-bottle half full of sodium hydroxide solution. Be sure to leave the first one empty. Now prepare in the flask a mixture of 50 c.c. of ethyl alcohol and 150 c.c. of concentrated sulphuric acid, adding the ingredients slowly and with constant shaking. Also put into the flask about 25 grams of sand. Close connec- tions and heat the flask cautiously on a wire gauze until gas evolution begins. Collect the gas in several test-tubes. Test first its inflammability. Shake up a test-tube filled with it with 1 c.c. of bromine water. Treat another test- tube of the gas with 1 c.c. of dilute potassium permanganate solution. OXIDATION OF AMYLENE. Page 129. Add 0.5 c.c. of amylene to 5 c.c. of a 5 per cent sodium carbonate solution. Then add drop by drop a 1 per cent solution of potassium permanganate and shake. ACETYLENE. Pages 129-133. Fill a graduate with water and invert it in a pneumatic trough. Now take a piece of calcium carbide about the size of a bean and by means of a pair of pincers introduce it under the edge of the graduate. When action has ceased, fill a U-shaped glass tube with water and pass one end of it under the edge of the graduate in the trough so that the arm rises 18 EXPERIMENTS IN ORGANIC CHEMISTRY into the gas inside. Now connect the other arm with a separatory funnel whose stem is also filled with water. Put in the bulb of the separatory funnel about 50 c.c. of an ammoniacal cuprous chloride solution, and by opening the stop-cock bring this solution into contact with the gas in the graduate. Note the absorption of the gas, and the formation of a reddish precipitate. EXERCISE XI. THE CONSTITUENTS OF MILK. Pages 146, 172, 203. Make 50 c.c. of milk distinctly alkaline with sodium hydroxide solution. Shake thoroughly in a separatory fun- nel with 25 c.c. of ether, and after separating the layers repeat the process with an additional 25 c.c. of ether. Mix the ethereal solutions, and evaporate off the ether in a small flask. The residue is "fat." Barely acidify the aqueous layer from which the fat has been removed with dilute acetic acid, stirring vigorously. Filter off the precipitated casein on a cloth filter, squeeze it out, dissolve in a very dilute ammonia solution, and reprecip- itate by a few drops of acetic acid. Filter the casein, squeeze out as before, and dry in the air. Combine the aqueous filtrates, bring just to boiling, and filter off the precipitated albumin and globulin, using paper. Evaporate the filtrate to syrupy consistency on a water- bath and allow to cool. Milk sugar should crystallize. SAPONIFICATION OF BUTTER. Page 146. Dissolve 15 grams of sodium hydroxide in 40 c.c. of water. Warm the mixture and add 10 grams of butter with constant stirring. Cook for about half an hour and cool. Skim off the half-solid upper layer and dissolve it in distilled water. INVERSION OF SUGAR 19 To this solution in a flask add an excess of dilute sulphuric acid and distill with steam until 50 c.c. have come over. Note the odor of the distillate, which consists largely of butyric acid and water. Pour out the contents of the flask, cool thoroughly, and separate the solid higher fatty acids which are not volatile with steam. If time permits repeat the experiment, using neatsfoot oil instead of butter. ACROLEIN FROM GLYCERIN. Pages 143, 144. Heat a little glycerin in a test-tube with anhydrous boric acid and test cautiously the odor of the vapors evolved. EXERCISE XII. INVERSION OF SUGAR. Page 172. Dissolve 20 grams of cane-sugar in 100 c.c. of water. Put some of the solution in the tube (2 decimeters long) of a polar- iscope, and note the direction and angle to which the plane of polarized light is deflected by the solution. Bring another portion of the same solution to boiling, add 3 drops of dilute sulphuric acid, and continue the boiling for ten minutes. After cooling to room-temperature, again test with the polariscope. If a polariscope is not available, test the sugar solution before and after inversion with Fehling's solution, remem- bering that after inversion enough alkali should be added to completely neutralize the sulphuric acid. To make Fehling's solution, dissolve 34.6 grams of copper sulphate crystals in water and make the solution up to 500 c.c. Dissolve 173 grams of Rochelle salt and 60 grams of sodium hydroxide in water and make this solution up to 500 c.c. Keep the solutions separate and mix as needed, using equal quantities of each. 20 EXPERIMENTS IN ORGANIC CHEMISTRY CELLULOSE. Pages 177-179. Dissolve 2 filter papers in 10 c.c. of cold concentrated sulphuric acid with constant stirring. When all has been dissolved, pour the solution upon 50 grams of finely pow- dered ice. Add 50 c.c. more of water, and boil the solution 15 minutes. Make a portion of the resulting solution just alkaline with sodium hydroxide and boil for a minute with Fehling's solution. Neutralize the remainder, filter it through animal charcoal, and observe its rotary power in the polariscope. Into 30 c.c. of cold water pour 50 c.c. of concentrated sulphuric acid slowly with constant stirring. Allow the solution to cool to room-temperature and introduce into it slips of filter paper. Remove after about 20 seconds, wash rapidly with running water, then with very dilute ammonia and finally again with water. Dry some of the paper, and notice the marked change in its physical properties. Moisten another part of the paper with a dilute solution of iodine in potassium iodide. Mix 20 c.c. of the most concentrated sulphuric acid with 10 c.c. of highly concentrated nitric acid. Dip into the solution bits of cotton wool, cotton cloth, and filter paper. Allow them to soak for from half to three-quarters of an hour. Then squeeze out the acid as much as possible, immerse rapidly in a large quantity of ice-water, wash thor- oughly, dry, and test the inflammability of the products formed. Test also their solubility in a mixture of alcohol and ether. UREA. Pages 187-189. Dissolve 2 c.c. of bromine in 100 c.c. of cold dilute sodium hydroxide solution. Fill a test-tube with this mixture and invert it in a beaker of the same solution. Now dissolve NITROBENZENE 21 separately 1 gram of urea in 10 c.c. of water. From a glass tube make a little dropper turned up at the end, and by means of this introduce under the edge of the test-tube about 0.2 c.c. of the urea solution. Test the gas evolved for nitro- gen by means of a glowing splinter. POTASSIUM XANTHATE. Dissolve 2 grams of potassium hydroxide in 25 c.c. of absolute alcohol and shake with successive quantities of carbon bisulphide until a precipitate forms. Add if neces- sary a small quantity of ether. Filter off the potassium xanthate, wash with a little alcohol, and dissolve in water. Test the solution for the presence of xanthates by the addi- tion of a few drops of a solution of copper sulphate. AMMONIUM SULPHOCYANATE. Pages 185, 192. Mix 10 c.c. of strong ammonia (sp. gr. 0.90) with 10 c.c. of 95 per cent alcohol and 20 c.c. of carbon bisulphide. Shake the mixture thoroughly and allow to stand 24 hours in a tightly stoppered bottle. Then evaporate off about two-thirds of the liquid (taking care that no flames are burning in the vicinity) and allow to cool and crystallize. EXERCISE XIII. NITROBENZENE. Pages 240, 241. Place 80 c.c. of concentrated sulphuric acid in a 500 c.c. flask and add gradually with frequent shaking 70 c.c. of concentrated nitric acid. Cool the mixture to room-tem- perature by immersing the flask in water, and then add gradually with constant shaking 60 c.c. of benzene. Keep the temperature of the mixture below 60° by cooling with water. When all the benzene has been added, place in the 22 EXPERIMENTS IN ORGANIC CHEMISTRY flask a cork through which passes a long vertical tube, and heat for an hour on a water-bath heated to 60°. At this point begin the preparation of aniline, for which see the second part of this exercise. Shake the flask containing the nitrobenzene frequently during the heating. Cool the mixture and separate the upper layer of nitrobenzene from the sulphuric and nitric acids in a separatory funnel. Wash the product by shaking it with water in the separatory funnel. Remember that the nitrobenzene is now the lower layer. Dry the washed product by heating with calcium chloride on the steam- bath until the liquid becomes clear. Then remove the calcium chloride by filtration through glass-wool and purify the filtrate by distillation, using a 100 c.c. flask and a con- denser from which the water-jacket has been removed. Col- lect the part of the product distilling from 205° to 210? ANILINE. Pages 241, 244-245. Place 45 grams of granulated tin and 25 grams of nitro- benzene in a 750 c.c. flask and add gradually 85 c.c. of con- centrated hydrochloric acid. Introduce the acid as follows: Add about 10 c.c. of it, attach a long glass tube to the flask as in the preceding experiment, and shake the mixture well. The reaction will begin rather vigorously, and as soon as this occurs immerse the flask in water to moderate the action, shaking vigorously as long as this produces any rise in temperature. Repeat until all the acid has been added. The latter half may be added in somewhat larger portions. Remember that the temperature need not be kept as low as in the preparation of nitrobenzene. The reaction should be vigorous but not stormy. Heat the mixture for an hour on the steam-bath and leave until the next exercise. ANILINE 23 EXERCISE XIV. ANILINE (Continued). Set up an apparatus for distillation with steam like that described in the textbook on page 8, using the largest avail- able flask for the purpose. Now mix the crude product which has been standing since the last exercise with a solu- tion of 75 grams of sodium hydroxide in 100 c.c. of water. Pour the resulting mixture into the flask of the steam-dis- tillation apparatus and while hot pass in a vigorous current of steam. The aniline liberated by the alkali is driven over with the steam. Continue the distillation till the distillate begins to come over clear, then cut off the steam-current, taking care to break the connections between the steam- boiler and the flask before turning out the gas under the former. Now place the turbid distillate in a separatory funnel. Add about 25 grams of sodium chloride for every 100 c.c. of the liquid and shake till the salt is dissolved. See that the liquid is thoroughly cooled and add about 50 c.c. of ether and shake thoroughly. Now allow the liquid to separate, run off the aqueous layer through the stop-cock at the bot- tom, pouring off the ethereal layer through the top into a small Erlenmeyer flask. Dry the ethereal solution by shak- ing it with three or four small pieces of solid potassium hydroxide. While the drying is going on set up the following appara- tus: Connect a 50 c.c. distilling-flask with a condenser, and pass through the stopper the stem of a separatory funnel. Now surround the flask with boiling water, and introduce the dry ethereal solution of aniline into the separatory funnel. Open the stop-cock of the latter carefully so as to allow the solution to drop into the flask at about the same rate that the ether distills over. When no more ether distills, 24 EXPERIMENTS IN ORGANIC CHEMISTRY substitute an air-condenser (a long piece of tubing of large bore) for the water-jacketed one, and a thermometer for the separatory funnel, and rectify the aniline by distillation, collecting the part which comes over from 175° to 185°. PHENOL. Pages 247-249, 257-259. Add to 1 gram of aniline in a test-tube 5 c.c. of water and 5 c.c. of hydrochloric acid (sp. gr. 1.12). Cool the solution in ice-water, and add to it gradually, keeping well cooled, about 3 c.c. of sodium nitrite solution (1:3) until after vigorous shaking a drop of the mixture produces a dark-blue spot upon a paper impregnated with potassium iodide and starch. Now insert in the test-tube a stopper with a de- livery tube and warm the mixture gently, collecting the gas evolved in an inverted 200 c.c. flask filled with 1:2 sodium hydroxide solution. Shake the bottle until no further absorption of gas takes place. Test for nitrogen by means of a glowing splinter. Now shake out the liquid remaining in the test-tube with about 10 c.c. of ether. Separate the layers in a separatory funnel and evaporate the ethereal solution in a small casserole on the water-bath. See that no flames are burning within 10 feet. When all the ether is evaporated, cool the residue by placing the casserole in ice. Note the odor of the prod- uct. Dissolve a very little in water and test the solution with litmus-paper. Add a few drops of a solution of ferric chloride. This is a characteristic test for phenol. To another small part of the solution add a little bromine water. A colorless precipitate of tribromphenol should appear. METHYL ORANGE 25 EXERCISE XV. PARAFUCHSINE. Pages 270-274. Place in a test-tube 1 gram of para-toluidine and 2.5 grams of aniline, adding also 3 grams of dry, solid mercuric chloride. Heat the mixture for an hour in a small oil-bath (beaker) to a temperature of 200° - thermometer in the oil. While the heating is going on try some of the experiments which follow. After an hour cool the deeply colored mass, rinse very rapidly with two 5 c.c. portions of cold alcohol to remove excess of aniline and toluidine. Finally boil the melt with successive 10 c.c. portions of alcohol, filtering each time through a folded filter. Test the dyeing power of this solution by dipping into it strips of white wool. PICRIC ACID. Pages 258, 259. Prepare a warm, saturated, aqueous solution of picric acid and dip into it pieces of wool and cotton. Wash out both with running water and note the difference in the way the two materials retain the dye. METHYL ORANGE. Page 254. Dissolve about 0.5 gram of sulphanilic acid in the least practicable quantity of warm dilute sodium hydroxide solution (1 per cent), and add 1 c.c. of 10 per cent potassium nitrite solution. In another test-tube cover 0.5 gram of dimethylaniline with an equal volume of water and add dilute hydrochloric acid drop by drop with constant shaking, 26 EXPERIMENTS IN ORGANIC CHEMISTRY until the oil just goes into solution, adding perhaps a drop in excess. To the solution thus prepared add drop by drop the solu- tion of sulphanilic acid described above. Shake after each addition till the precipitate first formed looks slightly crys- talline, then continue the addition until the color of the precipitate just changes from red to yellow. Now filter by suction on a hardened filter, scrape off the precipitate, and recrystallize from the smallest practicable quantity of hot water. Use a few drops of the mother-liquor to test the usefulness of methyl orange as an indicator. PHENOLPHTHALEIN. Pages 275-277. In a test-tube mix 0.2 gram of phthalic anhydride with a somewhat smaller quantity of phenol. Moisten the mass with 2 or 3 drops of concentrated sulphuric acid and heat gently for about two minutes by passing the tube carefully through the gas flame. About 150° is the desirable tempera- ture. When cold treat the fused mass with 10 c.c. of cold water, and add sodium hydroxide solution very gradually until no further change occurs. Dilute portions of the faintly alkaline solution and view obliquely from above by reflected light. Test its suitability as an indicator. FLUORESCEIN. Pages 275-277. Proceed as in the case of phenolphthalein, substituting resorcinol for phenol. INDIGO. Pages 277-279. To about 0.25 gram of indigo add an equal bulk of zinc dust, then add about 20 c.c. of a 1 per cent solution of sodium hydroxide and warm gently. Filter through a fluted filter 27 ALIZARIN into another test-tube in which has been placed a small piece of white cotton cloth. Saturate the cloth well with the liquid and dry thoroughly in the air. Finally wash in running water. Dyes which can be applied to the fiber in the manner just described are called "vat dyes." ALIZARIN. Pages 284, 285. Dip a piece of white cotton cloth in a test-tube containing a concentrated alum solution. Then squeeze it out and place in a test-tube containing ammonia. Bring to boiling and rinse off the cloth by one or two washings. Now mix 1 c.c. of commercial alizarin paste with 10 c.c. of water. Immerse in this the cloth just prepared and digest at a temperature near the boiling-point for about five minutes. Wash off as much of the paste as is practicable with running water. Then clear by covering the cloth with extremely dilute ammonia - 1 drop of ammonia to a test-tube of water. Finally wash again with running water and dry. If time permits, repeat the experiment, using soluble salts of other metals - iron and chromium, for example - instead of alum. INDEX. Acetaldehyde, 14. Acetic acid, 10. Acetic anhydride, 12. Acetyl chloride, 11. Acetylene, 17. Acetone, 15. Acrolein, 19. Aldehydes, 14. Alizarin, 27. Alkyl halides, behavior with silver nitrate, 9. Amylene, 17. Ammonium sulphocyanate, 21. Aniline, 22. Halides, behavior with silver ni- trate, 9. Halogens, tests for, 2. Indigo, 26. Inversion of sugar, 19. Iodoform, 6. Methane, 4. Methylamine, 15. Methyl orange, 25. Milk, constituents of, 18. Milk sugar, 18. Butter, saponification of, 18. Nitrobenzene, 21. Nitrocellulose, 20. Nitrogen, tests for, 1. Casein, 18. Cellulose, 20. Oxalic acid, 16. Ethyl acetate, 12. Ethyl alcohol, absolute, 4, 7. Ethyl alcohol, determination, 8. Ethyl alcohol, iodoform test for, 6. Ethyl alcohol, preparation by fer- mentation, 4, 7. Ethyl bromide, 8. Ethylene, 16. Paraffin series, solubilities, 5. Paraformaldehyde, 14. Parafuchsine, 25. Phenol, 24. Phenolphthalein, 26. Picric acid, 25. Potassium xanthate, 21. Fehling's solution, 19. Flash-point, 6. Fluorescein, 26. Formaldehyde, 14. Formic acid, 9. Fractional distillation, 7. Saponification number, 13. Sodium acetate, dehydration of, 4. Sugar, inversion of, 19. Sulphur, tests for, 3. Urea, 20, 29