Anthony Netzel

CHE 231 Section 801

8 March 2012

Finding Unknown two solids and two liquids through SIPCAn

Abstract:

The two liquid unknowns are separated by using simple distillation techniques. The

boiling points and densities of both substances are determined. The higher liquid has a boiling

point range of 148.0-153.3 °C and the density is .7784 g/mL. The lower boiling liquid has a

boiling rage 75.1-77.0 °C and the density .8470 g/mL. The calculated percent recovery for the

higher boiling liquid is 62.2%, and for the lower boiling point the percent recovery is 29.8%. The

two unknown solids are separated and isolated using acid-base extraction and crystallization

techniques. The solids are purified through recrystalization. The melting points of the pure

solids are determined. The mass of the pure organic acid is 2.44 g, and the percent recovery is

48.9%. The mass of the pure neutral organic solid is 1.54 g, and percent recovery is 30.9%. The

melting point range of the pure organic acid is 133.9-135.5°C. The melting point range for the

pure neutral organic solid is 48.7-49.7°C. The identity of all unknown liquids and solids are

confirmed using spectroscopy technique. The experimental values are compared to literature

values for further confirmation.

Introduction

In order to isolate and determine the two liquid unknowns, a simple distillation

experiment was conducted. The two unknowns were separated using simple distillation and

then characterized using boiling point and density determination. SIPCAn is an acronym used

for an organic laboratory technique. It stands for separation, isolation, purification,

characterization, and analysis1. The techniques can vary depending on the needs of the

situation. The distillation uses the different boiling points in order to separate two liquids

which are soluble one another. In order for simple distillation to work, the two liquids must a

have a boiling point difference that is greater than 25 °C2. The liquid mixture is heated up and

once the lower boiling liquid proceeds to boil, it vaporizes from the distillation flask into the

receiving flask leaving behind the high boiling liquid in the distillation flask. By having a large

difference in boiling points, the distillation can be stopped once the lower boiling liquid stops

vaporizing into the receiving flask and before the higher boiling liquid start to boil. This allows

for the two liquids to be isolated1.

In order to characterize the newly separated liquids, their boiling points were

determined. By heating a small sample of liquid and monitoring the temperature at which they

start to boil, the boiling points of both liquids can be determined. Density determination is also

used in order to characterize the liquid compounds. By massing a small sample of each liquid

and dividing this number by the total volume, the density can be calculated. The separation

and isolation of the liquid unknowns allows them to then be characterized. Characterization of

these liquids is important because it allows for their properties to be discovered which in turn

can provide more information about each liquid compound.

In order to separate two solid unknown to determine their properties, an acid-base

extraction was conducted. An acid-base extraction allows for the two solids to be dissolved into

two liquid solvents which can then be separated based upon their densities.2 The solids can

then be isolated from the liquid solvents using vacuum filtration and simple distillation so that

they can be characterized later1.

Acid-base extraction uses the principle of miscibility in order to separate and isolate two

liquids. In acid-base extractions two liquids form, one aqueous solvent and one organic solvent,

two distinct layers form separating them from one another based on their densities. The solid

unknowns are dissolved in these two liquids as well. The neutral organic solid dissolves into the

less dense aqueous solvent while the carboxylic acid dissolves into the more dense organic

solvent. The more dense liquid remains on the bottom and the less dense liquid remains on

top.3

The solid unknowns can then be isolated from their corresponding solvents. This can be

accomplished using either vacuum filtration or simple distillation. The carboxylic acid was

isolated from the aqueous solvent using vacuum filtration which vacuums through the solvent

and leaves behind the solid to be collected into a vial. In lab two, simple distillation was used to

separate two liquid compounds with a boiling point difference greater than 25°C2. Simple

distillation can also be used to isolate a solid from a solvent by distilling the organic solvent into

the receiving flask once it reaches its boiling point. The solid is then left behind and can be

collected into a vial for characterization later.

By separating and isolating the solid compounds, it is possible to find their physical and

chemical properties. In this experiment, these techniques are useful because it allows for one

to verify whether or not the compound was correctly identified.

Acid-base extraction and vacuum filtration were used in order to separate and isolate

the two solid unknowns. In order to purify them, the technique of recrystallization was used.

By dissolving the crude solids into a small amount of hot boiling solvent and allowing for this

mixture to cool to room temperature, the impurities were removed from the solid crystals.

However, the solvents used must meet three criteria requirements which include: being able to

dissolve the solid when hot, not dissolving the solid when cold, and being able to dissolve the

impurities when cold.1 A solvent that meets these criteria allows for the solid to dissolve in it

when heated and then recrystallize out of solution leaving behind impurities which remain

dissolved in the solution.

Once the solids were recrystallized, the crystals were collected using vacuum filtration.

Their melting point ranges of the pure solids were determined. Melting points were determined

using the mel-temp apparatus. A mel-temp apparatus heats up the capillaries at a constant

temperature and the temperature range from when the first crystal starts melting to when the

last crystals melts is recorded. Characterization of a solid allows for it to be identified. From this

information more chemical and physical properties can be found1.

In order to determine the molecular mass of a compound, mass spectrometry is the

most effective way with organic compounds. In mass spectrometry, the components of the

sample are ionized. This leaves only positively charged particles because the negative particles

are taken away. Electromagnetic fields separate the particles according to their mass to charge

ratio. Each mass and charge hits the detector in a different place. This is then computed into

the mass spectra. The presence of heteroatoms can also be determined using the mass

spectrum. An odd numbered molecular mass indicates the presence of carbon, hydrogen, and

nitrogen in the compound while an even numbered mass means carbon, hydrogen, and oxygen

are present. When the mass spectrum contains two adjacent peaks in a 3:1 ratio, chlorine exists

in the compound. Two adjacent peaks which are found in a 1:1 ratio indicate that bromine is

found in the molecule. Using this information, the molecular formula of the compound can be

determined and the index of hydrogen deficiency can be calculated.

IR Spectroscopy shines inferred light, which has a wave length of light between 4000-

400 cm-1, at the compound in question. Different bond vibrations absorb different wavelengths

of inferred light. Also the bond order, atomic mass and electro negativity effect absorption.

This absorption can be found in the IR Spectroscopy Spectrum. For example, O-H bonds form a

broad ban between 3600-3200 cm-1. If the broad band expands into the 3000 region is is most

likely an O-H bond to carboxylic acid. The region 4000-3000 cm-1 is where bans for H-X and C-H

sp2 and sp can be found. In 3000-2500 cm-1 is where C-H sp3 bans can be found. In 2500-1500

cm-1 is where C double and triple bonds can be found.

NMR spectroscopy is a laboratory technique that uses the magnetic effects of a spinning

charge. Many elements or their isotopes nuclei have spin. In lab, only ½ spins were observed.

Spins can be positive or negative. Negative spins have their magnetic spins reversed relatively

to the positive spin. The stronger the external magnetic field get the larger in difference

between eh positive and negative spin.

In proton NMR, even when the protons have the same spin they do not always show up

on the same area in the spectra. This is because of a phenomenon called shielding. Shielding is

when the bonds hydrogen has to carbon and the bonds the carbon has to other hydrogen

bonded carbons affect the resonance of the proton. In Carbon NMR, all of the carbons bonds

matter. A carbon is affect by its bonds to hydrogen. When bonded to carbon it is affected by

sigma and pi bonds and what that carbon is bonded to. Using the information provided by the

NMR spectrum, the molecular structure of the compound can be drawn and the connectivity of

the molecules can be determined.

Results

Once the liquids were separated the low boiling liquid was found to have a mass of

2.3147 g and a percent recovery of 29.80. The mass spectrum of liquid unknown 9 L.B. C4H8O2

exhibited a molecular ion peak at m/z of 88, with a base peak at m/z of 43, corresponding to a

C2H5O fragment (Table 1). Another prominent peak included one at m/z of 61 for C2H3. A third

one was at m/z 57 C2H3. The IR spectrum of liquid unknown L.B.9 exhibited a strong, narrow

absorption band at 1750 cm-1 and a weak but sharp absorption band at 1875 cm-1. Other

notable absorption bands in the IR spectrum were at 2990 and 3400 cm-1. The 1H NMR

spectrum of liquid unknown LB 9(Table 1) displayed the following four resonance signals: δ 1.10

(t, 3H), 2.05 (s, 1H), 4.10 (q, 4H). The 13C NMR spectrum of liquid unknown LB 9 displayed the

following three resonance signals: δ 15.0, 22.0, 66.0, 172.0.

The high boiling liquid had a mass of 4.8291 g and a percent recovery of 62.20%. The

mass spectrum of liquid unknown 9 H.B. C10H14 exhibited a molecular ion peak at m/z of 134,

with a base peak at m/z of 119, corresponding to a CH3 fragment (Table 2). Another prominent

peak included one at m/z of at 77 for C4H9. The IR spectrum of liquid unknown H.B.9 exhibited

a strong, narrow absorption band at 2990 cm-1 and a weak but sharp absorption band at 1600

cm-1. Other notable absorption bands in the IR spectrum were at 3100 and 1500 cm-1. The 1H

NMR spectrum of liquid unknown HB 9(Table 2) displayed the following four resonance signals:

δ 1.55 (s, 1H), 7.27 (t, 3H), 7.39 (t, 3H). The 13C NMR spectrum of liquid unknown HB 9

displayed the following three resonance signals: δ 30.0, 35.0, 125.0, 129.0, 156.0.

The melting point of R-Z 13 was found to be 49.1 C0 and the percent recovery was found

to be 32.51% for the crude and 30.86% for the pure. The mass spectrum of solid unknown 13 R-

Z C8H10O2 exhibited a molecular ion peak at m/z of 138, with a base peak at m/z of 138, whit the

first fragmentation at 123 corresponding to a CH3 fragment (Table 3). Another prominent peak

included one at m/z of 107 for CH3O. The IR spectrum of liquid unknown R-Z 13 exhibited a

strong, narrow absorption band at 1510 cm-1 and a weak but sharp absorption band at 2900

cm-1. Other notable absorption bands in the IR spectrum were at 3000 and 2800 cm-1. The 1H

NMR spectrum of liquid unknown R-Z (Table 3) displayed the following four resonance signals:

δ 3.75 (s, 1H), 6.85 (s, 1H). The 13C NMR spectrum of liquid unknown R-Z displayed the

following three resonance signals: δ 57.0, 115.0, 155.0.

The melting point of R-Z 13 was found to be 134.4 C0 and the percent recovery was

found to be 59.89% for the crude and 48.91% for the pure. The mass spectrum of solid

unknown 13 R-CO2H C7H5BrO2 exhibited a molecular ion peak at m/z of 200, with a base peak at

m/z of 200, whit the first fragmentation at 183 corresponding to an OH fragment (Table 4).

Another prominent peak included one at m/z of 155 CO2H. The IR spectrum of liquid unknown

R-CO2H 13 exhibited a medium, broad absorption band at 3100 cm-1 and a weak but sharp

absorption band at 2600 cm-1. Other notable absorption bands in the IR spectrum were at 2700

and 3000 cm-1. The 1H NMR spectrum of liquid unknown R-CO2H (Table 4) displayed the

following four resonance signals: δ 7.33 (s, 1H), 7.40 (t, 3H), 7.75 (d, 2H) 8.25 (s,1H). The 13C

NMR spectrum of liquid unknown R-CO2H displayed the following three resonance signals: δ

120.0, 128.0, 130.0, 132.0, 134.0 168.0.

Discussion

The unknown 9 low boiling point was found to be ethylethanoate. Using the mass

spectrum, the presence of a C2H5O group was detected based upon the radical fragment loss of

M-45 which according to literature data corresponds to a C2H5O group. Using the mass

spectrum, the molecular weight of the compound was determined to be 88 m/z and from this

the presence of oxygen was assumed due to the even numbered molecular mass. The IR

spectra showed the presence of a carbon to oxygen double bond at 1750 cm1-. The carbon

NMR indicated that there were four types of carbons. The proton NMR indicated that there

were 3 types of protons. This leaves the ethyl chain attached to the oxygen in the ethanoate

chain. The literature values of this compound are a boiling point of 77.1 C0 and density 0.897

g/cm3. The observed values of this compound were a boiling point of 76.6 C0 and density

0.841g/cm3.

The identity of the unknown 9 high boiling liquid was found to be t-butylbenzene. Using

the mass spectrum, the presence of a methyl group was detected based upon the radical

fragment loss of M-15 which according to literature data corresponds to a methyl group. Using

the mass spectrum, the molecular weight of the compound was determined to be 134 m/z and

from this the presence of oxygen was assumed due to the even numbered molecular mass. The

IR spectra showed the presence of a sp2 carbon to hydrogen double bond at 3100 cm1-. The

carbon NMR indicated that there were five types of carbons. The proton NMR indicated that

there were four types of protons. This leads to a tert-byutal attached to a benzene ring. The

literature values of this compound are a boiling point of 169.0 C0 and density 0.867 g/cm3. The

observed values of this compound were a boiling point of 150.0 C0 and density 0.7784g/cm3.

The unknown 13 R-Z was found to be 1,4-dimethoxybenzene. Using the mass spectrum,

the presence of a methyl group was detected based upon the radical fragment loss of M-15

which according to literature data corresponds to a methyl group. Using the mass spectrum,

the molecular weight of the compound was determined to be 138 m/z. The IR spectra showed

the presence of carbons in an aromatic ring at 1510 cm1-. The carbon NMR indicated that there

were three types of carbons. The proton NMR indicated that there were two types of protons.

This leads to a benzene ring with two methoxy chains on opposite ends. The literature values of

this compound are a melting point of 55.0 C0 and density 1.053 g/cm3. The observed value of

this compound was a melting point of 49.3 C0.

The unknown 13 R-CO2H was found to be 3-bromobenzoic acid. Using the mass

spectrum, the presence of a hydroxyl group was detected based upon the radical fragment loss

of M-17which according to literature data corresponds to a hydroxyl group. Using the mass

spectrum, the molecular weight of the compound was determined to be 200 m/z. The IR

spectra indicated the presence of a O-H bond with a broad ban at 3100. The carbon NMR

indicated that there were six types of carbons. The proton NMR indicated that there were five

types of protons. This leads to a carboxilate group attached to a benzene ring with a bromide

one carbon apart. The literature values of this compound are a melting point of 155.0 C0 and

density 1.983 g/cm3. The observed value of this compound was a melting point of 135.5 C0.

Experimental:

Lab 2: Separation of Two Unknown Liquid Compounds by Simple Distillation; Characterization

by Boiling Point and Density Determination

In order to separate two liquids using simple distillation, the mass of a 50 mL distillation

flask and 25mL receiving flask was taken. 20 mL of unknown compound 9 were then added to

the distillation flask and using mass by difference the mass of this liquid compound was

determined. A simple distillation apparatus was then set up and keck clips were used to hold

the glassware securely in place and a thermometer was inserted into the distillation flask close

to the neck of the flask. Using a heating mantle set to 40% power, the liquid in the distillation

flask was heated. Once the lower boiling liquid started to vaporize into the air then into the

receiving flask and the first drop appeared, the temperature was recorded. The compound was

left heating until all the lower boiling liquid had vaporized. The liquid in the 50 mL flask stopped

boiling.

The boiling points of both liquids were then determined using a boiling point apparatus.

A small amount of each liquid was transferred into a test tube and this was allowed to heat up

on a hot plate. A thermometer was inserted into this test tube and the hot plate was set to

175°C. Once the liquid started boiling, the range started and the temperature stabilized was

when the range stopped. This process was done for both the high and low boiling liquids. The

densities of both liquids were then determined by using a pipet and 1.00 mL of the liquid were

transferred into a tared flask. The mass of the liquid was then measured and this number was

divided by the total volume in order to calculate the density. This process was repeated for

both liquids and their percent recoveries were calculated and recorded. The high and low

boiling liquids were then transferred into separate vials and labeled and turned into the lab

instructor.

Lab 3: Separation of Two Solid Unknowns by Acid-Base Extraction

An acid-base extraction was conducted in order to separate two solid unknowns. 4.9901

g of unknown solid mixture 13 were dissolved in 50 mL of dichloromethane. This solution was

then transferred into a separatory funnel where twenty milliliters of 1.0 M NaOH solution was

added. The funnel was then inverted and swirled around making sure that the stopcock was

closed. It would occasionally be opened to release the built up pressure. It was then placed on a

ring stand and allowed to settle until the two liquids separated into two distinct layers. The two

liquid layers were then transferred into two separate beakers labeled aqueous phase and

organic phase. This procedure was once again repeated for the organic phase and the two

liquid layers were once again separated.

10 mLof 6M HCl were then added to the aqueous solvent and this solution was stirred

and placed in an ice bath and put aside. A small amount of magnesium sulfate was added to the

organic solvent a little at a time until a “snow-storm” effect took place inside the beaker. At this

point, the magnesium sulfate was decanted out of the liquid and the solid was disposed of in

the solid waste trash. The organic liquid was then put into a flask. From there, it was

transferred into a rotary evaporator till only a few milliliters are left. At this point, the flask was

removed and, the rest of the liquid was allowed to evaporate off. At this time the, aqueous

solvent was vacuumed filtered and the vacuum was left running for ten minutes until the solid

had been fully isolated from the solvent. The organic acid solid was then collected and

transferred onto a watch glass and placed in the oven at 115 C0 for ten minutes. While the solid

dried, the neutral organic solid from the organic solvent was collected and transferred into a

massed and labeled vial. After ten minutes in the oven, the organic acid was taken out of the

oven and allowed to cool to room temperature and it was then transferred into a massed and

labeled vial. The two vials containing the organic acid and neutral organic solids were then

turned in to the instructor.

Lab 4: Purification of 2 solid unknowns by recrystallization; Characterization by melting point

determination

The organic and aqueous sample collected in the previous lab were retrieved from the

instructor and massed. Using mass by difference, the mass of the crude solid compounds was

determined. Four melting point samples were then made (two for pure organic acid and two for

pure neutral organic solid) by gently tapping a small amount of the solid into the bottom of a

melting point capillary. 50 mL of the each solvent (MeOH for the acid and hexane for the

neutral) were gently heated at 150°C on a hot plate. The two crude solids were transferred into

two separate labeled beakers. Once the solvents were boiling enough solution to dissolve the

majority was slowly to each of their respective solids. This solution was then placed on the hot

plate and additional ethanol was slowly added to the organic acid to make it dissolve. The

neutral organic solid was taken off the heat and put aside to cool back down to room

temperature. Once the organic acid was dissolved it was taken off the heat and put aside. The

two solutions were cooled to room temperature and then they were placed in an ice bath and

allowed to cool further.

Once the neutral solid had cooled to a low temperature, the recrystallized neutral solid

was collected using vacuum filtration. The filter paper in the Buchner funnel was made damp to

crack the seal using the cooled hexane and the solution was poured in. The hexane was used to

wash the solid and the vacuum was kept on for ten minutes in order to fully dry the solid. The

solid was then collected and placed in a massed labeled vial. Vacuum filtration was used to

collect the acid and 1:1 MeOH was used in place of ethanol to dampen the filter paper and

wash the solid. After ten minutes, the organic acid was transferred to a massed and labeled vial.

The mass of both solids and their percent recoveries were then calculated.

Four melting point samples were then made (two for pure organic acid and two for pure

neutral organic solid) by gently tapping a small amount of the solid into the bottom of a melting

point capillary. Then a melting apparatus was used to find the melting point. The labeled vials

containing the carboxylic acid and neutral organic solid were then turned into the instructor.

Calculations:

Percent recoveries of separated liquid unknowns: By dividing the mass of the liquid component

by the mass of the total liquid mixture and multiplying this number by a hundred the percent

recovery of the liquid component can be calculated. This details how much of the liquid was

lost during the experimental process.

% recovery = (mass component (g) / mass mixture (g)) *100%

= (2.3147g / 7.7676g) *100%

= 29.80 % recovery of high boiling compound

Density of separated liquid unknowns: By dividing the mass of a specific volume of the liquid

component and dividing this number by the total volume the density of the liquid component

can be calculated.

Density = mass aliquot (g) / volume aliquot (mL)

= 0.8470g / 1.0 mL

= 0.8470 g/mL

Percent recoveries of recrystallized solid: By dividing the mass of the recrystallized solid

component by the mass of the total mixture and multiplying this number by a hundred the

percent recovery of the purified solid can be determined. This details how much of the solid

was lost during the recrystallization process.

% recovery = (mass of purified component (g) / mass mixture (g)) * 100%

= (2.4407g / 4.9901 g) * 100%

= 48.91% recovery purified carboxylic acid

References:

1 )Dintzner, M. CHE 231: Mechanistic Organic Chemistry I Lab: Winter Quarter 2011-2012;

Journal of Chemical Education: Chicago,Il, 2011.

2)Zubrick, J.W. Eds. The Organic Chem Lab Survival Manual, 8th ed.; John Wiley & Sons, Inc.:

Hoboken, NJ, 2010.

3) The Chemical Book http://www.chemicalbook.com. Date accessed March 1, 2012.