CHEM 2531 Lecture Notes - Lecture 3: Separatory Funnel, Stopcock, Sodium Hydroxide

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24 Dec 2019

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3: separation of an unknown carboxylic acid (rco2h) & a phenol (aroh) Liquid-liquid extraction involves partitioning compounds in a mixture between two immiscible phases (an organic phase and an aqueous phase) based either on differences in the compounds" acid-base properties or their solubilities in the two phases. You will separate a mixture of an unknown carboxylic acid (rco2h; see candidate list on last page) and 2-naphthol (aroh) by liquid-liquid extraction based on the difference in their acidities (consult your lab lecture notes for details). 1st) you will prepare an ether solution (the organic phase) of the two compounds; any minor impurities are non-acidic and will remain dissolved in the organic phase throughout the extraction process. 2nd) you will extract the rco2h from the organic (ether) phase into an aqueous phase by vigorously mixing the ether phase with an aqueous solution of nahco3 (a 10% solution of nahco3 (aq) has already been prepared for you).

Related Questions

Why do ionic compounds dissolve well in water? Select all that are true.

Question 5 options:

Because water and ionic compounds are both polar

Water molecules have partial charges that attract the ions in the solid compound, causing it to dissociate into separated ions

Because organic compounds are nonpolar

Water molecules can surround an ion, and neutralize the ion's charge using either it's partial positive or negative side.

The individual ions are solvated by water molecules which stabilizes the ions

2. Which compound is soluble in ether but not soluble in aqueous sodium hydroxide?

Question 2 options:

	ArOH
	Ar
	ArCOOH

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When you have a two-layer mixture of water and tert-butyl methyl ether, what physical property of these liquids assures you that the ether is the top layer?

Question 4 options:

low density was my answer was

You perform each extraction twice, first with 1 mL and second with 0.15 mL. Why is the second extraction necessary?

Question 8 options:

	several small extractions is better than one large one
	to remove any orgnaic material contaninating tube 2
	to remove any remaining neutral compound

7. Which of the following reactions is not favorable?

Question 7 options:

	ArCOOH + NaOH â ArCOO^-Na⁺ + H₂O
	ArOH + NaHCO₃ â ArO^-Na⁺ + CO₂ + H₂O
	ArCOOH + NaHCO₃ â ArCOO^-Na⁺ + CO₂ + H₂O

9.Why is phenol more acidic than an aliphatic alcohol?

Question 9 options:

	Its conjugates baseâs negative charge is localized on the oxygen
	Phenols have a stronger O-H bond
	Only the phenol can form hydrogen bonds
	Its conjugated base is stabilized by resonance

Which aqueous base reacts with a carboxylic acid but not with phenol? Why?

Question 10 options:

	Sodium bicarbonate, it is a weaker base and will only react with strong acids
	Sodium hydroxide, it is a strong base and will only react with strong acids
	Sodium bicarbonate, it is a weak base and will only react with weak acids
	Sodium hydroxide, it is a strong base and will only react with weak acids

1. How might your results be affected if you neglected to triturate the solid prior to recrystallization?

A. The product would not dissolve in the ethanol during recrystallization

B. Little or no product would be formed

C. The recrystallized product will likely contain some impurities leading to misidentification of the product

D. The only effect this might have is the formation of larger crystals during recrystallization

2. In the Wittig reaction, the nucleophile is

A. a phosphorus ylide

B. an enolate ion

C. the phase transfer catalyst

D. the carboxylic acid

3. What is the function of the dichloromethane used during the separation step?

A. It reacts with the benzyltriphenylphosponium chloride to form the butadiene product

B. Dichloromethane removes water from the reaction mixture

C. Dichloromethane is used as the phase transfer catalyst

D. It acts as the solvent for the desired product to separate it from the water soluble substances in the solution mixture

4. If you are uncertain which layer removed from a separatory funnel is which in terms of aqueous versus organic, how could you make that determination?

A. Weigh both layers and the heaviest was the bottom layer

B. Mix a small amount of water with a small sample of each layer and the one it dissolves in is the aqueous layer

C. The darkest colored layer is probably the organic layer

D. Heat the liquid from each layer and the one with the lowest boiling point is the organic layer

5. During the separation phase of the experiment, the diene product is being extracted from which layer?

A. acidic

B. Non-polar

C. Organic

D. Aqueous

6. What would be the volume of 92.1 mmol of trans-cinnamaldehyde? volume in mL

I would like to know about the answers of these questions based on the experiment of synthesis in Organic Chemistry 1: CONVERSION OF 1-Butanol to 2-METHYLHEXENES

CHEM 2531 Lecture Notes - Lecture 3: Separatory Funnel, Stopcock, Sodium Hydroxide

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