Nucleophilic Preparation Of 1-Bromobutane Lab Report

The objective of this laboratory experiment is to study both SN1 and SN2 reactions. The first part of the lab focuses on synthesizing 1-bromobutane from 1-butanol by using an SN2 mechanism. The obtained product will then be analyzed using infrared spectroscopy and refractive index. The second part of the lab concentrates on how different factors influence the rate of SN1 reactions. The factors that will be examined are the leaving group, Br – versus Cl-; the structure of the alkyl group, 3◦ versus 2◦; and the polarity of the solvent, 40 percent 2-propanol versus 60 percent 2-propanol.

Also, the similarity between the database reference of Isobutyl Acetate, reference IR data graph included, and the experimental IR would also suggest that the products are the same and suggest that the unknown reagent was Isobutyl Alcohol.

Abstract: In this experiment the conversion of alcohols to alkyl halides are investigated through reflux and simple distillation. These are common procedures used to separate substances. After the reflux and distillation is complete 13C NMR and IR spectrum is used to identify the product or products for each reaction: 1a, 1b, and 2. Every individual in the group was assigned either 1a (1-propanol) or 1b (2-pentanol), and 2 (1,4-dimethyl-3-pentanol). The purpose of this experiment was to understand and become familiar with the reaction mechanisms and be able to observe and compare the product or products for each of the reactions using 13C NMR and IR.

At this point the flask was attached to a refluxing apparatus. This process of refluxing helps to purify the mixture and keep the reaction at a constant temperature. Also, before the reaction mixture began to boil the separation of a clear top layer and a cloudy bottom layer helped to indicate that the reaction was working properly. The top layer was the alkyl bromide since the other components of the aqueous layer have the greater density. After the 45 minute refluxing process was complete, the apparatus was set up for simple distillation apparatus distillation commenced. Distillation took place until no more drops of product were dripping from the distillation head. The first drop of distillate occurred when the thermometer read 75°C, the actual temperature was probably a bit higher since the vapors might not have fully reached the bulb of the thermometer. The final drop of distillate was collected at about 115°C. Once the distillate was collected, it was placed in a seperatory funnel and the reaction flask was rinsed with 10 mL of water and added to the seperatory funnel. Rinsing the funnel ensured that all of the distillate from the distillation process was removed from the reaction flask and no product was left on the walls of the flask. After the water was added, two layers formed in the funnel. The top layer was the water and the bottom layer was the 1-bromobutane since the density of 1-bromobutane is higher than that of water.

On the other hand, the heating assists the reflux process by lowering the activation energy therefore heating triggers a catalyst increasing the reaction rate. In the reflux process, the 1-hexene pronates and forms a carbocation. This carbocation occurs due to the electrons from the pi bond of the carbons approaching the hydrogen electrons in HBr. After this, the reflux reaction is completed by the electrons of bromine approaching the carbocation resulting in the product of 2-bromohexane. After the reflux process, the solution is cooled to room temperature then add both 7mL of water and 7mL petroleum ether in order to separate the solution into organic and aqueous layers based on their differing solubilities and densities. In this addition, the tetrabutylammonium bromide enables the amount of addition to increase by enabling the HBr to be more reactive. After removing the aqueous layer, add sodium bicarbonate to further separate the organic layer into aqueous and organic. Then add anhydrous sodium sulfate until the solution is clear or the bottom of the flask is

In Figure 2, the IR spectrum that was produced from the reaction of 1-propanol the product of 1-bromopropane is given. There was not a presence of an OH bond, but there is a Csp3H bond at 2967 cm-1 and a CO bond at 1282 cm-1. Since there is no OH region, this

Based on 52 D: Chromic Acid Test 1, 52 H: Chromic Acid Test 2 and 52 C: Bromine in Methylene Chloride it was determined that the unknown substance followed an substitution reaction mechanism as well as contained an alcohol and aldehyde functional groups, table ___. The molecular components of the unknown where further narrowed down using IR, C13 NMR and proton NMR.

The retention time of unknown alcohol Q was 0.8125 min. The retention time of methanol was 0.6250 min. The refractive index values of unknown alcohol Q and 1-bromobutane were 1.3915 and 1.4345, respectively. These values are similar and comparable to the literature RI values of unknown alcohol Q and 1-bromobutane: 1.3990 and 1.4390, respectively. The unknown alcohol Q (1-butanol) had a O-H stretch at 3200-3650 cm-1 and a C-H stretch at 2850-2990 cm-1.

There should have been aromatic C-H stretches but there were not any shown. The reference spectrum showed those peaks while the product IR spectrum did not. From the reactions, the melting point of the hydrolysis is a few degrees above the literature values. Not only was the melting point range higher, it was also wide for a melting point of a pure substance. A reason for the wide range is because of an impurity in the sample and a reason for the melting point range to be higher was that there was too much product in the meting point tube and therefore had a higher melting point range. For part A, the synthesis of methyl benzoate, a low yield was obtained. A reason for this was that when rinsing the beaker with dichloromethane, not all of the product could have been rinsed out and some could have still been left in the beaker, decreasing our yield. Also, when removing the upper aqueous layer, some of the product could have been removed with it, resulting in a low

The experimental IR spectrum produced a weak stretch at just below 3000 cm-1, which can be attributed to the saturated carbon-hydrogen bonds present on the cyclic portion of the molecule. Additionally, a strong stretch at about 1700 cm-1 was observed indicative of the presence of a ketone. Furthermore, two stretches at 1600 cm-1 and 1500 cm-1 respectively were observed that indicates the presence of an aromatic ring. Finally, a stretch observed at about 825 cm-1 suggests the presence of a para substituted benzene ring. When the information in the IR spectrum is coupled with that from the H1NMR and the fact that spectrum from the starting materials (Figure 7) do not match, it can be concluded that the reaction was likely successful in yielding the desired

The boiling points recorded for both compounds were slightly off due to an error while performing the lab. The thermometer was set too low to the vigrex column, resulting in lower boiling points. This can be fixed by raising the thermometer in the stillhead to height of where the glassware splits. Even with this discrepancy, the identity of both compounds was still confirmed. For fraction A, the IR RM-03-IRA was obtained. This spectrum contains a peak at 2877 cm-1 and a peak at 1106 cm-1. The second peak shows that the compound contains an ether. The presence of this functional group and the lack of a carbonyl group and hydroxyl group eliminated 9 of the 13 possible unknowns. The NMR spectra eliminated the other three possibilities. The NMR spectra obtained for fraction A are RM-03-NMRA1 and RM-03-NMRA2. The 1H NMR, RM-03-NMRA1, showed only 2 types of protons present, one represented at 3.47 ppm and the other at 3.32 ppm. It also showed that there was acetone in the NMR tube by the presence of the peak at 2.09 ppm. There were only two compounds left that had two types of protons, 1,2-dimethoxtethane and

At this point, only the anisole was eliminated. The 1H NMR, RM-03-NMRC1, eliminated more options. The spectra showed that there were protons on a ring, multiplet at 7.32 ppm, and two other types of protons. One type of proton was a quartet at 2.74 ppm and the other was a triplet at 1.33 ppm. This data, if interpreted correctly means that the compound consist of an ethyl group and a ring. Other peaks shown on the spectrum RM-02-NMRC1 were two peaks for 1,2-dimethoxyethane, and one for acetone. This means that with fraction was slightly contaminated, as well as the NMR tube was not completely dry. At this point it was determined that the identity of the compound in fraction C was ethylbenzene. This identity was confirmed with the 13C NMR. The RM-03-NMR2C2 spectrum shows that six types of carbons were present. Two of the six types of carbons were sp3 hybridized and found in the 0-75 ppm region. The two peaks were found at 29.1 ppm and 16.0 ppm. In the region between 50-80 ppm, a peak for CDCl3 was shown, as well as, two small peaks from 1,2-dimethoxyethane. In the region of 100-150 ppm, a cluster for the carbons on the ring was found at 127.8 ppm and125.8 ppm, while an sp2 hybridized peak was observed at 144.4

The 2-methylcyclohexanol spectrum displayed peaks at 2950cm-1 and 3300cm-1, denoting the presence of C-H alkane functional group and O-H of alcohol functional group. However, the synthesized product spectrum showed peaks at 1650cm-1 and 3050cm-1. This indicated an absence of an O-H of alcohol group and a presence of C=C and C-H alkene functional groups. The absence of O-H alcohol functional group was logical since all of the possible products had alkanes and alkenes functional group but O-H alcohol functional group. The Br2 in CCl4 test was conducted to test for presence of an alkene group. The 2-methylcyclohexanol displayed a negative result however, the product and 1-decene resulted positive. The Jones Oxidation test was performed to test for presence of primary and secondary alcohol group. The product displayed a negative result but 1-decene and 2-methylcylohexanol showed a positive result. The results of boiling point determination, IR spectroscopy, and two chemical tests indicated that the 1-methylcyclohexene was successfully

The product was not pure, which can be seen on the H NMR spectra of the product, containing impurities that resulted in the integrations to be slightly off. On the H NMR spectrum, it appears that the H’s farther away from the carbonyl and ester have the impurities since those are the slightly off integrations. Moreover, the splitting patterns for these H’s show some irregularities, which may be due to the impurities. Although the some integrations are inconsistent with the predicted product, when adjusted to account for impurities, the spectrum does confirm the isolation of an ester with the number of H’s (18 H’s) and constitutionally inequivalent H’s (5 H’s) matching. On the other hand, the identification of the unknown alcohol, found to be 1-pentanol, was easier in the respect that the H NMR was not contaminated. The H NMR showed 12 H’s and 5 constitutionally inequivalent H’s with 6 of the H’s having quartets in the ppm range of alkanes, as well as having a H in the ppm range of a C-OH. In addition to the IR spectrum, which showed an OH stretch at 3328.20 cm-1, a CH stretch for alkanes around 2850-2930 cm-1, and a CO stretch for alcohols at 1053.75 cm-1, the proposed alcohol of 1-pentanol could be confirmed to be the unknown alcohol. In order of discovery, the unknown alcohol was first found in order to predict the product of the

The identification and characterization of the structures of unknown substances are an important part of Organic Chemistry. In this experiment a sample of an unknown aldehyde or ketone was obtained. From this sample two solid derivatives were prepared. Their melting points were obtained and compared to those listed in the Table of Aldehyde & Ketone Derivatives. From this the unknown sample was identified. As additional aid a Benedict’s test and Iodoform test were used. These are functional group tests used for distinguishing between aldehydes, ketones and methyl ketones. A Benedict’s test tests positive for aliphatic aldehydes and negative for aromatic aldehydes and ketones. An Iodoform test tests positive for methyl ketones and acetaldehyde