The objective of this experiment was the synthesis of Isopentyl Acetate using an esterification reaction between acetic acid and Isopentyl Alcohol, using a strong acid as a catalyst. The product was washed, and distilled. This approach is called Fisher esterification, whereby esters are produced by the esterification of a Carboxylic acid where it is heated with an alcohol in the presence of a strong acid which acts as a catalyst. The ester produced had a banana flavor. The extraction of the crude product was conducted using sodium bicarbonate followed by distillation.
The resulting product obtained was 4. 491g of Isopentyl Acetate, indicating a 70. 02 percent yield. Based on the IR data, it was verified that the end products were as desired. The Isopentyl Acetate carbonyl bond was evaluated to be around 1742. 88 cm-1. This indicated that the carbonyl from acetic acid had been utilized. In addition, the stretches of C-H and C-O matched well with what they are supposed to be. The results were overall consistent. The lab experiment provided information on the setting up of reflux apparatus and examining of an IR spectrum.
Introduction Infrared spectroscopy is a method of determining what functional groups are present in a certain compound. IR spectroscopy is one of many types of spectroscopy. The main idea behind spectroscopy is that matter and electromagnetic radiation can interact with each other in ways which are consistent. In infrared spectroscopy, when certain organic compounds are subjected to infrared radiation, the different functional groups present in the organic compounds react in different ways to the infrared radiation.
This can help determine what functional groups are present in certain organic compounds. In general, there are three characteristics present in a signal for a certain IR spectrum: wavenumber; how broad or narrow a signal shape is; and finally how intense a signal shape is. Wavenumber consists of knowing at which number on an IR spectra, certain types of bonds are likely to exist. Usually stronger bonds will appear at higher wavenumbers because they will be excited at frequencies which are higher.
For instance, for a molecule that contains a triple bond, a double bond, and a single bond, the triple bond would have the highest wavenumber in the IR spectrum of that molecule followed by the double bond in the molecule, and then the single bond in the molecule. Also, in the bonds of organic molecules, a bond with a smaller atom will give a higher wavenumber while a bond with a larger atom will have a lower wavenumber. For instance, if the analyzed organic molecule has a carbon-oxygen bond and a carbon-hydrogen bond, the signal for the carbon-oxygen bond will occur at a lower wavenumber than the signal for the carbonhydrogen bond.
Finally, specific functional groups will exist on an IR spectra at certain wavenumbers and with certain intensities. For instance, alcohol will produce a large and broad signal at a frequency of 3400 cm-1. Amines will produce medium and broad signals at a frequency of 3500cm-1. Carbonyl groups will produce a large and sharp signal and a frequency of 1715 cm-1. A carbon-carbon triple bond will produce a small signal at a frequency of 2250-2100 cm-1, and a carbon-nitrogen triple bond will produce a medium signal at a frequency of 2250 cm-1.
Also, in this experiment a process of distillation was used where the banana oil was separated from the crude ester mixture. Distillation usually works because organic compounds have boiling points which are different from each other. Usually a mixture of two compounds is placed in a round bottom flask. Heat is then applied to the mixture in the round bottom flask and as a result, the compound present in the mixture with the lower boiling point vaporizes first. The vapor is then condensed in a condenser because the condenser has cool water to cool the vapor.
The condensed vapor then travels into another flask at the other end of the distillation apparatus. Separation Scheme Mechanism There were six main steps which allowed Acetic acid and Isopentyl Alcohol to combine and form Isopentyl Acetate. The first step involved hydrogen being added to the oxygen on the carbonyl group of the Acetic acid. The second step involved a pair of electrons from the oxygen in the Isopentyl Alcohol attacking the carbon double bonded to the oxygen on the Acetic acid. Then the newly formed structure would have three alcohol groups present.
The third step involved removing the hydrogen from the positively charged oxygen in this newly formed structure. The fourth step involved the addition of hydrogen to this newly formed structure. The hydrogen would form a positively charged H20 group. The fifth step involved a pair of electrons transferring from oxygen in the alcohol group and forming a double bond with carbon resulting in oxygen gaining a formal charge of +1. The pair of electrons connecting the carbon to the charged H20 group would attack the oxygen on the charged H20 group forming water.
The water could then be used in the final step to deprotonate the hydrogen connected to the oxygen with a positive charge resulting in the formation of Isopentyl Acetate. Procedure First, a reflux apparatus was set up with a round bottom flask at the bottom. Second, 5ml of Isopentyl alcohol, 7ml of glacial acetic acid, and 1 ml of sulfuric acid were added to the round bottom flask and mixed. Third, the round bottom flask was then attached to the reflux apparatus, and turned on for 60-75 minutes.
Fourth, the mixture from the round bottom flask was poured into a separatory funnel. Fifth, 10 ml of water was added to the separatory funnel and the funnel was shaken. The water layer was then discarded with the mixture from the round bottom flask was retained in the flask. Sixth, 5 ml of 5% aqueous sodium bicarbonate was added to the separatory funnel and the funnel was shaken. The 5% aqueous sodium bicarbonate layer was then discarded with the mixture from the round bottom flask retained in the flask.
Seventh, 5ml of aqueous sodium chloride was added to the separatory funnel and the funnel was shaken. The aqueous sodium chloride layer was then discarded with the mixture from the round bottom flask staying in the flask. Finally, the crude ester solution was distilled using a distillation apparatus. The distillate was then obtained, its mass was taken, and an IR was done on it. Results Infrared Spectroscopy of Distillate IR -Isopentyl Acetate Functional Group Odor Carbonyl, C=O 1742. 88 C-H 2961. 7 C-O 1239. 88 O-H 3,465. 02
Discussion Isopentyl Acetate has a boiling point of 142°C and thus it vaporized first out of the crude ester mixture. According to the IR spectra received for the sample of Isopentyl Acetate, there were three main signals present. The first of the three signals was present at a wavenumber of 2,961. 70 cm-1. A signal at this wavenumber indicates that there are hydrogen-carbon bonds present in this sample of Isopentyl Acetate. According to the structural formula of Isopentyl Acetate, carbon-hydrogen bonds are indeed present in its structure.
The second of the three signals was present at a wavenumber of 1,742. 88 cm-1. A signal at this wavenumber indicates that there is an ester group present in this sample of Isopentyl Acetate. According to the structural formula of Isopentyl Acetate, a carbonyl group is present in its structure. The final of the three signals was present at a wavenumber of 1,239. 88 cm-1. A signal at this wavenumber indicates that there is a carbon-oxygen group present in this sample of Isopentyl Acetate.
According to the structural formula of Isopentyl Acetate, a carbon-oxygen group is indeed present in its structure. There was one unexpected signal present in the sample at a wavenumber of 3,465. 02 cm-1. The presence of this wavenumber indicated that an alcohol group was present in the Isopentyl Acetate sample. However, there was no alcohol group present in the structural formula of Isopentyl Acetate. Therefore, the result of this alcohol signal probably came from the hexane which was being used to allow the IR machine to read a sample of Isopentyl Acetate.
Some sources of error that could have contributed to the percent yield not being ideal include the Isopentyl Acetate being evaporated out of the crude Ester solution in the distillation apparatus or the reaction not going to completion during the reflux step. Conclusion Isopentyl Acetate was produced as a result of an esterification reaction between Acetic Acid and Isopentyl Alcohol. The percent yield was 70 percent. Separation of the crude product was conducted by extraction using a separatory funnel, and drying was done by using sodium carbonate. The purification was conducted using distillation.
Since esterification reactions are slow, they need a catalyst like inorganic acids. The reactants need to be refluxed in order to increase the yield of the product. Reflux is technique used for distillation and its primary purpose is to supply energy to chemical reactions over an extended period of time. In most organic reactions, the reaction is very slow. To speed up the reaction, heating is generally used. Since many organic compounds are characterized by low boiling points, they vaporize when subjected to heat, thereby preventing the reaction to completion.
To prevent this from happening, heating under reflux is used where a condenser is attached to prevent the reagents from escaping. There are many commercial and industrial applications of synthesis of esters with respect to perfumery and flavoring. Esters produced by synthesis include: synthetic ester (essence); octyl acetate (orange); Isopentyl isovalerate (apple); methyl butyrate (pineapple); Isopentyl Acetate (banana); isobutyl formate (raspberry); methyl anthranilate (grape); benzyl acetate (peach); benzyl butyrate (cherry); and pentyl butyrate (apricot).
Distillation has many applications in real life, including converting salt water into fresh water; in the production of alcoholic drinks where distillation produces a stronger drink; and also in the making of perfumes. When perfumes are made, certain natural essential oils from plants are extracted by passing steam through the plant. This steam is then condensed and the end product is concentrated oil.
