Untitled Essay Research Paper The purpose of

Untitled Essay, Research Paper

The purpose of this laboratory assignment was two-fold, first, we were to

demonstrate the extraction of acids and bases, finally, determining what unknowns were

present. Second, we were to extract caffeine from tea. These two assignment will be

documented in two separate entities.Introduction: Acid/base extraction involves carrying out simple acid/base reactions in

order to separate strong organic acids, weak organic acids neutral organic compounds

and basic organic substances. The procedure for this laboratory assignment are on the

following pages.3) Separation of Carboxylic Acid, a Phenol and a Neutral Substance The purpose of this acid/base extraction is to separate a mixture of

equal parts of

benzoic acid(strong acid) and 2-naphthanol(weak base) and

1,4-dimethoxybenzene(neutral) by extracting from tert-butylmethyl ether(very

volatile).The goal of this experiment was to identify the three components in the mixture

and to determine the percent recovery of each from the mixture.4) Separation of a Neutral and Basic Substance A mixture of equal parts of a neutral substance containing either

naphthalene or

benzoin and a basic substance containing either 4-chloroaniline or ethyl 4-aminobenzoate

were to be separated by extraction from an ether solution. Once the separation took

place, and crystallization was carried out, it became possible to determine what

components were in the unknown mixture, by means of a melting point determination.

Results

Procedure Observations InferenceDissolve 3.05g Phenol Mixture was a golden-

Neutral acid in 30ml brown/yellow color

t-butyl methyl ether in

Erlenmeyer flask and transfer

mixture to 125ml separatory

funnel using little ether to

complete the transferAdd 10 ml of water

Organic layer=mixture

aqueous layer=water(clear)Add 10 ml saturated aqueous Sodium

bicarbonate NaHCO3 dissolves in

solution sodium bicarbonate

water.

to funnel and mix cautiously

with stopper onVent liberated carbon

Carbon dioxide gas

dioxide and shake the mixture was released three times

thoroughly with frequent venting

of the funnelAllow layers to separate Layer = H2O +NaHCO3

completely and draw off

lower layer into 50ml Erlenmeyer

flask 1Add 10ml of 1.5 aqueous NaOH Flask 2 = H2O + NaHCO3

(5ml of 3M and 5ml H2O) to

separatory funnel, shake mixture,

allow layers to separate and draw

off lower layer into a 25ml

Erlenmeyer flask 2. Add additional

5ml of water to funnel, shake as beforeAdd 15 ml NaCl to funnel. Shake Bottom layer is white and

NaCl was added to

the mixture and allow layers to separate gooey. wash the ether

and draw off lower layer, which is layer and to remove

discarded organic substances

NaOH and NaHCO3

Pour ether layer into 50ml

Erlenmeyer flask from the top

of the separatory funnel

(not allowing any water

droplets to be transferred)

Flask 3Add anhydrous NaSO4

to ether extract until it no

longer clumps together

and set it asideAcidify contents of flask 2 Litmus went from

Acidification was now

by dropwise addition of blue to pink.

Flask complete

concentrated HCl while 2 = creamy color

testing with litmus paper

and cool in iceAcidify contents of flask 1 Litmus went from

Acidification was now

by adding HCl dropwise blue to pink. Flask

complete

while testing with litmus 2 = white solution

paper and cool in iceDecant ether from flask

3 into a tared flaskBoil ether with boiling chipsDo a vacuum filtration and Solution turns

to a Crystallization is now

recrystallize ether by dissolving it solid. complete

in 5ml, taking out boiling chips,

adding drops of Ligroin until the

solution was cloudy and cool it

in iceIsolate crystals from flask 2 by Crystals = creamy-white Dried crystals

are now

vacuum filtration and wash with powder

ready for melting point

a small amount of ice water

determination

and recrystallize it from boiling

waterRepeat the above for flask 1 Crystals = white

powderFlasks number 4 and 5 were done by the following diagram.

Results:As a result of this acid/base experiment, the following results were obtained:

Flask 1: 31.113g

-30.223g

.890g

Flask 2: 36.812g

-36.002g

.810g

Flask 3: 90.789g

-90.114g

.065g

% yield = experimental weight x 100%

theoretical weight

Flask 1: .890g x 100% = 89%

1.00g

Flask 2: .810g x 100% = 81%

1.00g

Flask 3: .675g x 100% = 67.5%

1.00g

When taking the melting points of the unknowns, flasks 4 and 5, I came

to the

conclusion that the samples contained, benzoin, melting point of 13

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