The alcohols 1-propanol and 2-pentanol were converted into alkyl halides through a certain series of steps. The first step was reflux, and the purpose of reflux is to add energy to the solution and not lose any solution to evaporation. This energy helps initiate the acid-catalyzed dehydration reaction and also promotes rearrangement. The next step was distillation, which functioned to separate liquids based on boiling points. The distillation utilizes boiling points to separate the alkyl halide products from many impurities that might exist. Reflux is the first step instead of distillation because refluxing allows the reaction to progress. If distillation was performed first, separation would begin before the reaction was allowed time to …show more content…
For example, since the voltage adapter connected to the sand bath may not have been working properly, inconsistent heating patterns could have proposed a problem during reflux. Also, a few extra drops of water may have invaded the product while the flask was cooling in the ice bath during distillation. Furthermore, it is possible that not all of the organic layer was drained out of the separatory funnel during separation, and maybe the drying agent was not allowed enough time to remove all of the water. Errors will always hinder the success of a reaction, which will greatly effect the percent yield.
Infrared spectroscopy (IR) is a very useful tool that can read a molecule’s functional groups from a small sample. By monitoring the disappearance and appearance of certain groups, it is possible to confirm wether compounds have formed. In this experiment, for example, the reactants are alcohols, whose IRs will show a large and broad absorption around 3500 cm-1. These hydroxide groups are eventually replaced during the reactions, and the final products will not contain any hydroxides. Therefore, the IR of the products will not show the large and broad hydroxide absorption. Monitoring the disappearance of the hydroxide stretch will allow the reaction progression to be monitored also. The complete disappearance of this stretch will confirm that a new product has been formed. However, IR
A few sources of potential error are as follows: loss of product on glassware throughout the experiment, inadequate measuring of chemicals, "impure" chemicals being worked with, and loss of final product during crystallization processes.
14 mL of 9 M H2SO4 was added to the separatory funnel and the mixture was shaken. The layers were given a small amount of time to separate. The remaining n-butyl alcohol was extracted by the H2SO4 solution therefore, there was only one organic top layer. The lower aqueous layer was drained and discarded. 14 mL of H2O was added to the separatory funnel. A stopper was placed on the separatory funnel and it was shaken while being vented occasionally. The layers separated and the lower layer which contained the n-butyl bromide was drained into a smaller beaker. The aqueous layer was then discarded after ensuring that the correct layer had been saved by completing the "water drop test" (adding a drop of water to the drained liquid and if the water dissolves, it confirms that it is an aqueous layer). The alkyl halide was then returned to the separatory funnel. 14 mL of saturated aqeous sodium bicarbonate was added a little at a time while the separatory funnel was being swirled. A stopper was placed on the funnel and it was shaken for 1 minute while being vented frequently to relieve any pressure that was being produced. The lower alkyl halide layer was drained into a dry Erlenmeyer flask and 1.0 g of anhydrous calcium chloride was added to dry the solution. A stopper was placed on the Erlenmeyer flask and the contents were swirled until the liquid was clear. For the distillation
A chemical reaction is when substances (reactants) change into other substances (products). The five general types of chemical reactions are synthesis (also known as direct combination), decomposition, single replacement (also known as single displacement), double replacement (also known as double displacement), and combustion. In this lab, the five general types of chemical reactions were conducted and observations were taken before, during, and after the reaction. Then the reactants and observations were used to determine the products to form a balanced chemical equation. The purpose of this lab was to learn and answer the question: How can observations be used to determine the identity of substances produced in a chemical reaction?
In figure 13, it can be seen that the reading wave infrared spectra of the ACS contained a large adsorption band around the wavelength that is at 2400-2800 cm-1 with two adsorption area, that isat wavelengths around 2000-2300 cm-1 with a stretch, and at a wavelength around 750-900 cm-1 with a stretch. Chemical activation using KOH can improve hydroxyl groups, as shown in Figure 13 wherein the adsorbent has a range of 3100-3600 cm-1. Adsorption bands at these wavelengths identify alcohol and phenol in O-H stretch on the surface of the adsorbent.
Possible reasoning for a lower yield could be loss of product during separation process, particularly leaving some product behind in Erlenmeyer flask. Another possible explanation could be the wash of product with not enough cold water, which increases the solubility of the product, thus lowering the yield. Also the product was lost during purification process, recrystallization. Solid could be dissolved below the boiling point of the solution, thus required more solvent, resulting in a lower
In this experiment, distillations were done. This is a technique that utilizes the differing boiling points of two or more compounds in a mixture in order to separate the compounds from the mixture. The way fractional distillation works is that the initial mixture is boiled up to the point of the lower boiling point compound; this compound then evaporates. This compound is then
1. Suggest at least one chemical reason why your percent yield is less than 100%. (Incomplete reactions? Side reactions? Stability of reagents?)
Purpose: The purpose of this experiment is to observe a variety of chemical reactions and to identify patterns in the conversion of reactants into products.
Simple distillation is a separation technique which can be used to separate and purify distillates from a liquid mixture which ideally contains one volatile and one non-volatile compound. If such ideal conditions are not possible—as is usually the case—then simple distillation can be applied as long as the liquid in question is composed of compounds that differ in volatility such that their boiling points differ by at least 40 to 50 degrees Celsius. Because
There are four main regions of IR absorptions: region 4000 – 3000 cm-1 corresponds to N-H, C-H and O-H stretching, region 2250- 2100 cm-1 is triple-bond stretching , region 2000- 1500 cm-1 is double bonds and the region below 1500 cm-1 is the fingerprint region where a variety of single bonds are absorbed.3 The chromic acid test is a test for oxidizability and gives a positive result for primary and secondary alcohols as well as aldehydes2. A positive result in the chromic acid test is indicated by a color change and the formation of a precipitate. Tertiary alcohols give negative results for the chromic acid test since there must be a hydrogen present on the alcoholic carbon for oxidation to occur. The 2,4 DNP test, tests for a carbonyl and is therefore a dependable test for aldehydes and ketones. Finally, 13C NMR spectroscopy is a test to determine the structure of a compound. 13C NMR detects the 13C isotope of carbon. Each carbon has a different chemical shift. A carbon’s chemical shift is affected by the electronegativity of nearby atoms. Carbons that are bonded to highly electronegative atoms resonant downfield because the electronegative atom pulls electrons away from the nearby carbons and cause those carbons to resonant downfield1 (John McMurry, 2008). A general trend is that sp3-hybridized carbons absorb from 0 to 90 ppm, sp2-hybridized carbons resonant between 110
The purpose of this experiment was to separate a two component mixture using fractional distillation. Distillation is a process of vaporization than condensation of a substance, used primarily to separate substances from a mixture when there are different boiling points. Fractional distillation is when the mixture has multiple substances with similar boiling points, and a fractional column is used to create multiple vaporization/condensation cycles. Fractional distillation is important when two or more substances need to be separated, but they have similar boiling points.
A good yield of isopentyl acetate was obtained during this experiment. Loss of the product was likely through transferring liquid from separatory funnel to the Erlenmeyer flask and residual material left in the distillation flask. Using an organic solvent like benzene or cyclohexane as a transfer agent would improve the yield, since their boiling points were around 80 oC and could be easily separated from the final product through simple distillation. However this
An ester was synthesized during an organic reaction and identified by IR spectroscopy and boiling point. Acetic acid was added to 4-methyl-2-pentanol, which was catalyzed by sulfuric acid. This produced the desired ester and water. After the ester was isolated a percent yield of 55.1% was calculated from the 0.872 g of ester recovered. This quantitative error was most likely due to product getting stuck in the apparatus. The boiling point of the ester was 143° C, only one degree off from the theoretical boiling point of the ester 1,3-dimethylbutyl, 144 ° C. The values of the
For this experiment, Alcohol D and Acid 2 reacted in the presence of concentrated sulfuric acid, resulting in a colorless solution with brown layer on top. After washes with sodium bicarbonate and brine, the pale-yellow liquid product was dried and then distilled. Distillation resulted in two colorless fractions, the second of which had a boiling point of 69-70 ˚C. This boiling point is unrealistic for any compound obtained in this experiment, so it was not used in identifying the product. After distillation, both fractions were spectroscopically analyzed. The IR and NMR spectra obtained for both fraction were identical, meaning both fractions contained exactly the same substance. Both fractions also smelled the same, like piña colada, therefore confirming this conclusion. This outcome also meant that the amount of product synthesized was 5.7393 g.
drop one of them and it was to shatter, you must not pick it up