In this experiment you will produce a solid mixture composed mainly of various monosaccharides, disaccharides and polypeptide compounds. Since a great deal of heating is necessary to bring about the desired chemical and physical processes, care must be taken to avoid extensive thermal degradation (pyrolysis) of the product. Also cleanliness is necessary, since the product will be subjected to analysis by mastication. During the analysis you are to make observations regarding the production of the neural transmitter acetyl choline in the synaptic junctions.
--saucepan with a capacity of one or two liters
--62 grams of a saturated monosaccharide solution containing D-glucopyranose and D-fructofuranose (about 1/4 cup)
--75 grams of the disaccharide a-D-glucopyranosyl-b-D-fructofuranoside (about 1/2 cup)
--20 mL of hydroxic acid
--20 grams of partially hydrogenated vegetable fat esters (about 1.5 tablespoons)
--thermal insulating material
--50 to 60 grams of arachin, conarchin, oleic-linoleic glyceride protein pellets (about 1/4 to 1/3 cup)
--4 grams of sodium bicarbonate (about 1 teaspoon)
--5 mL of either 4-hydroxy 3-methoxy benzaldehyde or 4-hydroxy 3-ethoxy benzaldehyde (about 1 teaspoon)
--thermometer (capable of reaching a temperature of at least 150 degrees Celsius)
--1000 square centimeters of aluminum foil
--a large insulated manual stirring device
1. Mass out 62 grams of the saturated monosaccharide solution and place it into the saucepan along with 20 mL of hydroxic acid.
2. Into a clean 250 mL beaker, mass out 75 grams of a-D-glucopyranosyl-b-D-fructofuranoside (sucrose) and transfer it to the monosaccharide solution in the saucepan.
3. Heat the mixture slowly, stir constantly, and bring to a boil. Use as cool a flame as will maintain boiling. You must avoid thermal degradation of the saccharides.
4. Mass out 10 grams of partially hydrogenated vegetable fat esters and add to the saccharide mixture in the saucepan. Continue to heat and stir using some kind of thermal insulating material to prevent overheating your epidermis.
5. Mass out 50 grams of protein pellets and add to the saccharide mixture in the saucepan when the temperature of the mixture reaches 138 degrees Celsius (280 ¡F). Continue to stir and heat the mixture.
6. Mass out 4 grams of sodium bicarbonate and obtain 2 mL of 4-hydroxy 3-methoxy benzaldehyde or its substitute. Lightly lubricate a square piece of aluminum foil which measures about 30 centimeters on a side with partially hydrogenated vegetable fat esters. Note: You are only getting these substances ready to add they are not to be added until step 8!
7. When the temperature of the solution reaches 154 ¡C remove the saucepan from the heat and place near the piece of aluminum foil. Also, remove the thermometer at this time and check to make sure that the mercury bulb is still attached to the base of the thermometer. If the bulb is not attached THROW THE PRODUCT AWAY.
8. While one partner holds the sauce pan and is prepared to stir the mixture the other partner adds first the 4-hydroxy, 3-methoxy benzaldehyde and then adds the sodium bicarbonate. STIR VIGOROUSLY. When the mixture foams pour it on the aluminum foil and spread to a depth of O.5 cm.
9. When cool break up the product and subject it to analysis by mastication. Be sure to give some to your instructor so that he can analyze it and determine if the product meets the U.S.P. purity grade.
Questions and Problems
1. Determine the percentage yield of product using the ocular method of approximation.
2. Comment on the amount of neural transmitter produced in the synaptic junctions during the mastication analysis.
3. In your opinion which of the following grades of purity are met by the product: Reagent, USP, or Tech.?
4. During step 8 of the procedure the mixture foamed due to the decomposition of sodium bicarbonate. Write the balanced equation of this reaction.