Write the equations for the acid-base reactions involved in this experiment. Clearly show the reactants and products for each chemical equation. Experiment: seperation of caffeine and benzoic acid by acid-base extraction Things used in lab: -solid mixture of caffeine and benzoic acid -40mL of dichloromethane -20mL of 1.0 M NaOH -magnesium sulfate as drying agent for caffeine isolation -3.00 M HCl for recovery of benzoic acid

Write the equations for the acid-base reactions involved in this experiment. Clearly show the reactants and products for each chemical equation. Experiment: seperation of caffeine and benzoic acid by acid-base extraction Things used in lab: -solid mixture of caffeine and benzoic acid -40mL of dichloromethane -20mL of 1.0 M NaOH -magnesium sulfate as drying agent for caffeine isolation -3.00 M HCl for recovery of benzoic acid

EBK A SMALL SCALE APPROACH TO ORGANIC L

4th Edition

ISBN:9781305446021

Author:Lampman

Publisher:Lampman

Chapter90: High-performance Liquid Chromatography (hplc)

Section: Chapter Questions

Problem 1P

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In this experiment a mixture of approximately equal amounts of three compounds - benzoic acid, 2-naphthol, and hydroquinone dimethyl ether - will be separated by a series of liquid-liquid extractions and purified by recrystallization. The first two compounds are acidic (but of considerably different acid strengths) and the third is neutral. Discuss the purification technique used in this experiment, Liquid-Liquid extraction, how does it work? Which core principle does it rely on? (acid-base chemistry)- expand on this. How is acid-base chemistry used to extract compounds? To explain your answer, make sure to use the pKa's of the compounds in your discussion for evidence of how it works.
why is it necessary to test the ph? PROCEDURE To a six inch test tube was added thiamine hydrochloride (0.65 g), followed by water (2mL). The mixture was gently shaken until homogeneous, and then ethanol (7.5 mL)was added. Finally, sodium hydroxide (10%, 1.5 mL) was added and the mixture wasgently stirred to ensure complete mixing.Benzaldehyde (3.8 mL) was then added at room temperature in one portion with gentlestirring. The pH of the resulting reaction mixture was determined and adjusted to >10by dropwise addition of 10% sodium hydroxide.
The purpose of this experiment is to use both extraction and crystallization techniques to separate a solid mixture of organic compounds. You will receive a packet with 1 g of a unknown (pH is basic) amide solid sample which will contain three components, one from each group: Group 1 (~50% wt): ethyl 4-aminobenzoate, ortho-toluic acid, or benzoic acid Group 2 (~40% wt): fluorene, 1,4-dibromobenzene, benzil, benzoin Group 3 (~10% wt): fluorene, 1,4-dibromobenzene, benzil, benzoin (but not the same as Group 2 compound) Create a lab procedure that will allow you to successfully isolate, purify, and identify the two major (Group 1 and Group 2) components of the unknown amide sample. reagents that can be used are 1M HCl, 6M HCl, 1M NaOH, 6M NaOH, diethyl ether, and methylene chloride
2.1g of sample are dissolved in methylene chloride and the sample is extracted with an aqueous solution of acid and base. Three compounds are isolated - 0.7g of ethyl p-aminobenzoate, 0.6 g of acetanilide, and 0.5 g of benzoic acid. Calculate the % composition of ethyl p-aminobenzoate in the recovered mixture. (Round the answer to 1 significant figure. Give just the number, not a % sign.)
What is the result in this experiment? ESTIMATION OF SODIUMHYDROXIDE USING HYDROCHLORIC ACID (CONDUCTOMETRIC TIITRATION)
Which of the following could DECREASE the amount of the recovered crystals in the purification by recrystallization experiment? Collecting the recrystallized benzoic acid by filtration using a pre-weighed filter paper. Using a long-stemmed funnel in the hot filtration step. Cooling the filtered solution rapidly. Washing the recovered crystals using hot solvent. a. II, III b. II, IV c. II, III, IV d. I, II, III, IV
20 tablets containing the dibasic drug ethambutol hydrochloride (MW 277.2 g/mol) were powdered. 0.3354 g of tablet powder was dissolved in 10 mL of 2 M sodium hydroxide and was extracted with 5 x 25 mL quantities of chloroform. The combined extracts were evaporated and the residue was dissolved in 100 mL of anhydrous acetic acid. Non-aqueous titration was carried out using 1-naphtholbenzein solution as indicator and 0.1014 M acetous perchloric acid. Volume of acetous perchloric acid required = 14.2 mL, weight of 20 tablets = 3.367 g, state content of ethambutol hydrochloride per tablet = 100 mg. Calculate the % of stated content in the tablets.
Which of the following is expected to achieve the best recovery of an organic compound from an aqueous solution? 1.Three extractions with 20 mL of ethyl acetate per extraction (60 mL total) 2.Two extractions with 30 mL of ethyl acetate per extraction (60 mL total). 3.One extraction with 60 mL of ethyl acetate. 4.In theory these extractions yield identical recoveries of the organic compound.
Some procedures include the addition of sodium carbonate before liquid-liquid extraction. What is the purpose of this step?
Solubility of Amines in AcidPut 2 ml of water in a 10x75-mm test tube. Add 5 to 10 drops of aniline. Add 6 N hydrochloric acid dropwise until the aniline dissolves. Then add 6 N sodium hydroxide until the aniline reappears. Write the observations/results in this experiment and the reaction equation.
6.0 mL of cyclohexanol, 8 mL of 85% phosphoric acid, and 10 drops of sulfuric acid are added to a 50-mL round-bottom flask with boiling chips, and the mixture is distilled into an ice-cooled receiver. The distillate is in the form of a colorless bi-phasic mixture. The cyclohexene upper layer is removed from the water layer, and dried over anhydrous calcium chloride. Isolated is cyclohexene as a clear and colorless foul-smelling liquid. Weighing data is given below. Gross mass: 51.24 g Tare mass: 48.04 g Product mass: 3.2g Question: Calculate the theoretical mass of the cyclohexene product, bearing in mind that the cyclohexanol starting material was measured by volume, not by mass (so you must use the density of cyclohexanol to convert milliliters to grams, before calculating the number of moles). Calculate the percent yield of cyclohexene obtained.
Why is sodium chloride added before extraction the aqueous layer with DCM? How does magnesium sulfate break emulsions?