Question

In: Chemistry

A student is working on the separation of a three-compound mixture, consisting of a carboxylic acid,...

A student is working on the separation of a three-compound mixture, consisting of a carboxylic acid, amine, and neutral compound, and starts by extracting the dichloromethane solution of the mixture with 10% NaHCO3 rather than 5% HCl. Assuming the student recognizes the error before proceeding further, would the student still be able to separate and identify the components of the mixture? Describe what changes would have to be made to the remainder of the procedure in order to do so.

Solutions

Expert Solution

A. The three-component mixture is first dissolved in ether. Water containing HCl is added and the mixture is shaken. This allows the R-NH2 to become converted to R-NH3+ and dissolve in the water.

However as you have already added NaHCO3 , I suggest neutralize it with excess of HCl

B. The mixture is carefully shaken to allow completion of the reaction.

C. The water containing the R-NH3+ is transferred to a 2nd container and purified to remove any non-amine compounds.

D. The amine is isolated. By adding aqueous NaOH the HCl is neutralized and the conjugate acid is converted back to the amine. The resulting cloudiness is due to the re-formation of the amine which is not very soluble in water. The crude amine is isolated by filtration.

E. The ether layer contains the carboxylic acid and the neutral compounds. These fractions are separated into its components by adding 1 mL of 3 N aqueous NaOH.

F. The bottom layer of water containing the R-COO2- ions is transferred to another container. These negatively charged ions are balanced with Na+ ions left from the reaction of NaOH.

G. This aqueous layer is purified by removing any non-acids from it.

H. The bottom layer of water containing the R-COO2- ions is transferred to a 2nd container. These negatively charged ions are balanced with Na+ ions left from the reaction of NaOH. This aqueous layer is purified by removing any non-acids from it.The crude acid is isolated by filtration. Thus the solid carboxylic acid is isolated

I The non-acid compound remaining in the ether layer is then purified and isolated. It is first purified by addition of pure water, then the ether layer is separated from the water and dried and then the ether is removed by evaporation


Related Solutions

What is the mechanism for separating 9-fluorenone and a carboxylic acid in mixture? We are using...
What is the mechanism for separating 9-fluorenone and a carboxylic acid in mixture? We are using a separatory funnel and adding the mixture of 9-fluorenone and a carboxylic acid to it. I need to know the mechanism of how they will separate into an aqueous and an organic layer.
Postlab Questions 1.     A student claims that a given unknown is a carboxylic acid because the...
Postlab Questions 1.     A student claims that a given unknown is a carboxylic acid because the sample dissolves in water, 10% NaOH, and 10% NaNCO3. Critique this conclusion. 2.     Explain how solubility tests could be used to differentiate between: a. a phenol and a carboxylic acid. b. a phenol that contains electron-withdrawing groups and a phenol that contains electron-donating groups. c. a carboxylic acid and an amine. d. 1-bromooctane and dibutyl ether. e. 2-pentyne and pentane. f.   2-nitropentane and 2-aminopentane....
A white powder, consisting of a simple mixture of tartaric acid (C4H6O6) and citric acid (C6H8O7)...
A white powder, consisting of a simple mixture of tartaric acid (C4H6O6) and citric acid (C6H8O7) was analysed to determine the elemental composition. Combustion of a 495.3-mg sample produced 610.5 mg of CO2 and 180.6 mg of H2O. Use atomic masses: C 12.011; H 1.00794; O 15.9994. 1) Calculate the % hydrogen, by mass, in the sample. 2) Calculate the % oxygen, by mass, in the sample 3)Calculate the % citric acid, by mass, in the sample.
What is the general formula of a carboxylic acid?
What is the general formula of a carboxylic acid? Give details about carboxylic acid.
If you are given a mixture consisting of anisole, benzoic acid, and fluorenone how would you...
If you are given a mixture consisting of anisole, benzoic acid, and fluorenone how would you devise a method to separate and isolate the two major components of this mixture (anisole and benzoic acid). The possible techniques to be used would be distillation, extraction, or recrystallization.
I need to know the procedures of the experiment below : Separation of a Three-Component Mixture...
I need to know the procedures of the experiment below : Separation of a Three-Component Mixture by Extraction ​ benzoic acid     ethyl 4-hydroxybenzoate diphenyl sulfone A 1.5-gram sample of a 1:1:1 (by weight) mixture of benzoic acid, ethyl 4-hydroxybenzoate and diphenyl sulfone was added to a 125 mL separatory funnel. Isopropyl acetate (20 mL) was added to the separatory funnel and the mixture swirled until all solids had dissolved. The solution was sequentially extracted with saturated aqueous NaHCO3 solution (4...
Separation of a Mixture – Pre lab 1. Where do you find in nature the three...
Separation of a Mixture – Pre lab 1. Where do you find in nature the three components that we will separate in this lab? What are they used for? (hint - an internet search is helpful) 2. If a student started with 4.2 grams of the mixture and recovered .75 g NaCl; 1.35 g SiO2; and .24 g CaCO3 what was the percent yield? 3. Think of a way in which physical separations are used in our world and describe...
I have a mixture consisting of 0.180 M nitrous acid, and 0.150 M sodium nitrite. NOTE:...
I have a mixture consisting of 0.180 M nitrous acid, and 0.150 M sodium nitrite. NOTE: pKa (nitrous acid) = 3.14. 7. First, I add 2.00 mL of 0.500 M HCl to 20.00 mL of the original (sodium nitrite / nitrous acid) mixture. Assuming these volumes are additive, make an ICE table and: a) Write the corresponding balanced reaction, specifying ALL of its relevant reactant and product components. b) Calculate how many moles of each relevant reaction component are initially...
In a Diels-Alder reaction why doesn't the carboxylic acid attack the ester to reform the acid...
In a Diels-Alder reaction why doesn't the carboxylic acid attack the ester to reform the acid anhydride?
In a Diels-Alder reaction, why doesn't the carboxylic acid attack the ester to reform the acid...
In a Diels-Alder reaction, why doesn't the carboxylic acid attack the ester to reform the acid anhydride? Why this Diels-Alder provides the cis-ring juncture instead of the trans?
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT