Experiment 7 Synthesis and Reactivity of tertbutyl chloride via an SN1 Reaction PDF

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Synthesis an d Reactivity tert-Butyl Chloride Via an SN1 Reaction Dennis Rossi and Roger Mendez CHM 2210L TA: Suzeeta Bhandari March 5 , 2019

Introduction: Substitution reaction is when an atom replaces the halide ion. The reaction occurs when an electron-rich atom attacks an electron-poor atom. This releases the leaving group that’s already attached to the molecule. This reaction is similar to a Brønsted-Lowry acid-base reaction. Where the nucleophile is attracted to the electrophile and the leaving group leaves. A substitution reaction can include in either SN1 and SN2. A SN1 occurs in two steps, usually where the C-X bond breaks and then it is replaced with the nucleophile. The time when the leaving group leaves and the nucleophile attaches, created a carbon cation where the central carbon that was bonded to the leaving group has a formal positive charge. When the nucleophile attacks the molecule, it is free to attack from both sides of the carbon atom forming a racemic mixture. On the other hand, SN2 mechanism occurs in one step. The C-X bond breaks and the nucleophile attacks at the same time. When a SN2 reaction occurs the stereochemistry is switched because unlike SN1 there is no room for the nucleophile attack, so it must attack from the back or the opposite side of the leaving group. Some factors that may affect the rate of SN1 and SN2 are whether the nucleophile is strong or weak, the leaving group, the stability of the carbon cation, and the type of solvent. In order for a SN1 and SN2 reaction to occur there must be good leaving groups; for example, OH- is pour leaving group because it is a strong base therefor it is sometimes transferred into H2O (which is a good leaving group) by the addition of a H+. Another factor is the nucleophile should be strong like I, Cl, or Br. For SN1, the is an intermediate, and this intermediate may rearrange to form a more stable carbon. Also another factor that may affect the rate is the solvents; SN2 favors polar aprotic solutions while SN1 favors polar protic solvents.

Main Reaction:

Side Reaction:

Experimental Section: The HCl and 5ml of t-butyl alcohol was added to a separatory funnel

15 ml HCl was cooled to about 5 o C

Once the layers were seperated, the H2O was then discarded

10-15 mL of H2O was then added to the funnel

The funnel was vented periodic ally

The aqueous layer was discarded

The main fraction was collected in a preweighed sample bottle and the boiling point was recorded

The separatory funnel was swirled for 20 minutes

When layers were separate , 10-15 mL of 5% NaHCO3 was added to the separatory funnel

The product was transferred into a 125 mL Erlenmeyer flask

A simple distillation apparatus was set up and boiling stones

When the layers were separated, the HCl layer was discarded

30 mL H2O was added to the separatory funnel

2-4g of anhydrous CaCl2 was added to dry

It was then decanted into a dry round b fl k

B) 0.1 mL tbutyl chloride was added to test tube 1 &2

4 test tubes were dried and cleaned. They were all labeled

0.2 mL 1Chlorobuta ne was added to test tube 3 &4

1 mL of 18% acetone/NaI was added to test tubes 1 &3 and shook vigorously

1 mL of 1% ethanol/AgNO3 was added to test tubes 2 & 4 and shook vigorously

The color was observed and recorded

The color was observed and recorded

Table of Contents Molar

Melting

Boiling Point

Mass

Point (oC)

(oC)

(g/mol)

Hydrochlor 36.46

Concentrati

Concentratio

ic Acid

on

n Dependent

Chemica l

Structure

Densit y

Formula

(g/cm3

HCl

) 1.2

t-butyl

74.12

Dependent 25.81

82.2

C4H10O

0.781

84.007

50.0

851

NaHCO3

2.2

110.99

772

1935

CaCl2

2.15

169.872 212

440

AgNO3

4.35

149.89

661

1304

NaI

3.67

58.44

801

1465

NaCl

2.16

alcohol

Sodium Bicarbonat e

Calcium Chloride

Silver Nitrate

Sodium Iodide

Sodium Chloride

Acetone

58.08

-95

56

C3H6O

0.784

Sodium

102.89

747

1396

NaBr

3.21

92.556

-123.1

78.5

C4H9Cl

0.880

92.57

-26

123.8

C4H9Cl

0.840

Bromide

1chlorobuta ne tert-butyl chloride

Hydrochloric Acid

t-butyl alcohol



Corrosive to metals



Highly flammable



Skin corrosion



Harmful if inhaled



Eye damage



Causes serious eye irritation



May cause respiratory irritation



Keep container tightly closed in well-



May cause damage to organs



Keep container tightly closed in well-

ventilated place Sodium Bicarbonate 

Causes eye irritation

ventilated place

Calcium Chloride 

Serious eye irritation



May cause respiratory irritation



Keep container tightly closed in well-

ventilated place Silver Nitrate



Keep container tightly closed in wellventilated place

Sodium Iodide



Oxidizer



May cause skin and eye irritation



Ay be corrosive to metals



Keep container tightly closed in well-



Causes severe skin and eye irritation



Respiratory irritation



Keep container tightly closed in well-

ventilated place Sodium Chloride

ventilated place

Sodium Bromide



No hazards



No hazards



Keep container tightly closed in well-



Keep container tightly closed in well-

ventilated place Acetone

ventilated place



Highly flammable



Causes serious eye damage



May cause dizziness and drowsiness



May cause damage to organs



Keep container tightly closed in well-ventilated place

Results:

Tert-butyl

Mass (g) 1.32

Percent Yield % N/A

Melting Point (oC) 49

Color Observed

Appearance of

Time of Precipitate

chloride

Test Tube #1 Test Tube #2 Test Tube #3 Test Tube #4

Clear with a yellow tint White silk color Clear Clear

precipitate No Precipitate (-) White Precipitate (+) No precipitate (-) No precipitate (-)

(s) No time recorded No time recorded No time recorded No time recorded

No calculations could be done for percent yield because no initial mass of tert-butyl chloride was recorded. To calculate the percent yield then the final mass (experimental) will be divided by the initial mass (theoretical) and then multiplied by a 100 to get the percent yield.

Percent yield %=

experimental x 100 theoretical

Discussion: For this experiment there was no % yield calculate because no initial mass of tert-butyl chloride was recorded. Do to human error the mass of the tert-butyl chloride was not recorded because it was forgotten and left out. In test tube #1 there was no precipitate, in test tube #2 there was precipitate, in test tube #3 there was no precipitate, and in test tube #4 there was no precipitate formed. In all of the test tubes the reactions occurred rapidly so that is why no time were able to be recorded. The main procedure instructed that if there were no reactions visible for 5 minutes then to place it in 50 oC water bath. However, the exact happened. As soon as the second chemical was put in the test tubes with the first chemical, a reaction immediately happened. Three out four test tubes resulted in expectations that were had. Test tube #1 was negative, test tube #2 was positive, test tube #3 was negative and test tube #4 was negative. In test tube #1, tert-butyl chloride is a tertiary alkyl halide therefore there was no reaction with NaI. For test tube #2, there was a reaction between 1-chlorobutane and AgNO3 because 1-

chlorobutane is a primary alkyl halide, therefore a SN1 reaction was able to happen. For test tube #3, there was no reaction however, it was predicted that there would be a reaction because 1chlorobutane, a primary alkyl halide, will react with NaI through a SN2. There may be several reasons why there was no reaction. The first could be because all the reaction occurred rapidly, the 3rd test tube wasn’t waited for and put into a water bath. Another reason may be that the test tube wasn’t cleaned properly and had other chemical residue that interfered with the reaction. Depending on the type of substrate, solvent, and temperature where the reaction occurs, will be effect the rate of SN1. As seen in the test tubes, one test tube had a reaction occure this because the others had different solvents and substrates that were not compatible to have a SN1 reaction occur. The temperature which the test tubes were in were room temperature. Therefore , increasing the temperature will provide the mechanism with more energy to occur quicker. Conclusion: The theoretical background and the results that were gathered, do correlate with each other. As SN1 was discussed, one was able to learn what solvents and substrates will work the best. The reaction in the test tubes put this the test. As if we seen which chemical will react in the silver nitrate test or the sodium iodide test. Knowing the background of tert-butyl chloride, one knows that the tert-butyl chloride will react with silver nitrate (AgNO3). The main objective of this experiment is to prove that whether silver nitrate or sodium iodide will react with tert-butyl chloride. The data reveals that the results of the experiment correlate with the background provided. SN1 reactions occur in cow digestive systems as their bodies digest carbohydrate. Cellulose are made of long glucose molecules bonded by glyosidic bonds. The enzymes that

break these bond are called glycosidase. Cows have bacteria tin their stomach that contain this enzyme. SN1 occurs during the breakage of these carbohydrates by breaking the bonds with water and alcohol leaves. This is a simple substitution reaction. There is a removal of a leaving group creating a oxonium ion intermediate and as the water nucleophile attacks from the bottom side. The experiment did accomplish what it set out to do. All reactions except one did what they were supposed to do. And that one reaction that did not occur correctly due to human error. For the most part the experiment set out what it was meant to do. References: Libretexts. “27.2: Introduction to Substitution Reactions.” Chemistry LibreTexts, National Science Foundation, 23 Feb. 2019, chem.libretexts.org/Bookshelves/General_Chemistry/Map:_General_Chemistry_(Petrucci_et_al. )/27:_Reactions_of_Organic_Compounds/27.02:_Introduction_to_Substitution_Reactions. Accessed 5 Mar. 2019. Libretexts. “9.2: Digestion of Carbohydrate by Glycosidase - an SN1 Reaction.” Chemistry LibreTexts, National Science Foundation, 23 Feb. 2019, chem.libretexts.org/Bookshelves/Organic_Chemistry/Book:_Organic_Chemistry_with_a_Biolog ical_Emphasis_(Soderberg)/Chapter_09:_Nucleophilic_substitution_reactions_II/9.2:_Digestion _of_carbohydrate_by_glycosidase_-_an_SN1_reaction. Weldegirma, Solomon. “Experiment 3: Chromatography – Analyzing Analgesics by TLC and Isolation of β – Carotene by Column.” Tampa, Pro-Copy Inc. 2018. 15-20.

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