??? Which above is more polar naphthalene or benzoic acid? Explain. What is the

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Which above is more polar naphthalene or benzoic acid? Explain. What is the purpose of adding NaOH solution to the initial organic phase? What is the purpose of adding HCl solution to the aqueous phase after completion of the initial extraction? What is the purpose of washing the organic phases with NaCl solution? What property of a solvent determines whether it is the top or bottom layer? Based on your answer, predict if each of the following organic solvents will be the top or bottom layer in an aqueous extraction (you will need to look up the information needed about each solvent to answer the question) toluene: methylene chloride: diethyl ether: hexanes: ethyl acetate: If during an extraction you are unsure as to which layer is which, what simple maneuver would you do? You have 10 grams of a compound. Eight grams is soluble in 100 ml of boiling solvent and 3 grams is soluble in 100 ml of cold solvent. What is the minimum amount of solvent you will need to dissolve your compound? What is the maximum yield of crystals you would expect? Show your calculations. You perform recrystallization on 60 mg of crude solid material and recover 45 mg of pure solid. What is the percent recovery? If further concentration of the mother liquor offers an addition 8 mg, what is the total percent recovery?

Explanation / Answer

1)Benzoic acid

Carboxylic acids are very polar, usually they are only soluble in polar solvents like water. You can think of it that since there are 2 oxygens compared to the aldehydes one carbon, it is more polar.

2)Adding NaOH is going to deprotonate any acidic carbons on any molecules in the organic phase. One deprotonated, molecules will have a charge and charged molecules are more soluble in polar protic solvents, such as water. When the aqeous layer is removed, all that remains is the desired end product in the organic layer.

3)

4)To remove unreacted Benzoic acid.

The bulk of the water can often be removed by shaking or "washing" the organic layer with saturated aqueous sodium chloride. The salt water works to pull the water from the organic layer to the water layer. This is because the concentrated salt solution wants to become more dilute and because salts have a stronger attraction to water than to organic solvents.

Note: sometimes a saturated aqueous solution of sodium chloride is called brine.

5)

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