Modern organic chemistry recrystallization lab PDF

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Modern organic chemistry recrystallixation lab that has been completed with backgrounf reasearch and other required elememts for the course...

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Jones

Name: Jasmine Jones ID: jaj03386 Chemical Purification: Identifying an Unknown Organic Compound using the Recrystallization Technique I.

Introduction The purpose of this lab is to identify an unknown organic compound in an impure sample by using a purification laboratory technique known as recrystallization to isolate and identify the compound. During the lab, the compound will be isolated using the recrystallization process and identified by its melting point. The laboratory techniques used during this experiment are recrystallization, filtration, and melting point determination. The recrystallization technique involves the use of heat to breakdown the impure compound so that its contents may be separated and isolated via suction filtration. Temperature control is imperative during this process of solvation as so to ensure that the crystalline lattice of the can be broken down and reformed in the absence of impurities. Moreover, the filtration process implements a technique known as suction filtration that is necessary for the collection of the crystals formed during the isolating of the unknown compound. Lastly a metal temp apparatus is used to conduct the melting point determination technique. The dryness of the sample is imperative to ensure an accurate reading of the sample which is imperative to correctly identifying the unknown compound that has be recrystallized. The primary reactant, being the impure compound, acts as a solute and by the end of the lab has been chemically separated using a solvent, into separate compounds that can now be identified using melting point determination.

Jones II.

Table of Reagents

Chemical Name Acetanilide

Structure

Molecular Weight 135.16g/mol

Benz amide

m-Nitrobenzoic Acid

113 °C to 118 °C

205.136 g/mol

153°C to 156 °C

122.123 g/mol

121 °C to 124°C

Benzoic Acid

Ethyl 3,5dinitrobenzoate

Melting Point

240.171 g/ mol 91 °C to 92 °C

167.12 g/mol

140°C to 143°C

Jones O-Toluic Acid

136.15 g/mol

103°C to 106°C

138.122 g/mol

158°C to 160°C

152.15 g/mol

81-83 °C (lit.)

Salicylic Acid

Vanilin

IV. Safety Information Reagent Safety Information: Acetanilide Benzamide Benzoic Acid Ethyl 3,5-dinitrobenzoate m-Nitrobenzoic Acid O-Toluic Acid

May cause eye/ skin irritation & harmful if digested Harmful if swallowed or absorbed through the skin. May cause eye and skin irritation. Causes eye, skin, and respiratory tract irritation. Harmful if swallowed. May cause sensitization by inhalation and by skin contact. Can irritate skin/eyes, must rinse. Should not be inhaled or ingested. Harmful if swallowed. Causes eye, skin, and respiratory tract irritation. Possible risks of irreversible effects. Harmful if swallowed. Causes eye, skin, and respiratory tract irritation.

Jones Salicylic Acid

Vanillin

Causes severe eye irritation. Causes skin and respiratory tract irritation. May be harmful if swallowed. Light sensitive. May cause central nervous system effects. May cause reproductive and fetal effects May cause eye, skin irritation . May be harmful if digested

There is a burn caution emphasized during this lab, the use of boiling water and handling hot glassware are main components of the experiment. The use of boiling chips is required to prevent overheating and never heating a closed vessel. The standard safety googles, and hand gloves are also required prior to the start of the experiment.

V. Experiment: Apparatuses:

Obtain 1 gram of the online substance and stir the mixture prior to measuring into the sample. -

Add 25-50 mL of water and several boiling chips to a 125mL Erlenmeyer flask and heat the

water to a boil using a hotplate (do not overheat) and on a second hotplate place 125 mL Erlenmeyer glass and add one gram of the solid unknown compound into it along with the boiling chips.

Jones - Pour approximately 5-10 mL of the boiling water into the flask containing the impure solid using a ring clamp as a handle and swirl the mixture for one minute at a consistent temperature and add small (3-5mL) aliquots of boiling water as needed until unknown solid is fully dissolved. Stir consistently in between, and use a spatula to break any clumps. - Set up the gravity filtration system with a short stem funnel lined with folded filter paper and covered with a watch glass to place on a 125 mL Erlenmeyer flask that should contain a few milters of boiling water and maintain a constant temperature using a hotplate. (May need to moisten filter paper with small amount of hot water to prevent cooling). - After filtering rinse the filter paper with 2-3mL of boiling water to dissolve any access crystals and remove flask from the hotplate. As the filtrate cools, check for crystal formation. If no crystals induce them with a stirring rood by scratching the inner wall of the flask. Once crystallization is complete put the flask in an ice bath for 5-10 minutes - Using a Buchner funnel and a 250 mL filter flask, collect the recrystallized solid using suction filtration. Wash the crystals with 2-3ml of cold water and press with a spatula. Set vacuum to pull for 10-15 minutes to dry then scrape the crystals into a tared watch glass to weigh the mass. - Once sample is sufficiently dry determine the melting point and identify using the table of reagents. To verify melt a 50:50 mixture of the unknown sample and the standard sample that is believed to be the unknown and observe for a variance of 5°C of greater and repeat with the standard sample with the next closest melting point. Record data.

Jones...