A Friedel-Crafts Alkyla

tionIntroduction:In order to produce an alkyl atomic act 18ne, redolent(p) ring usually nethergo the Friedel-Crafts alkylation. This is usually d sentience in the armorial bearing of an alkyl halide with a Lewis unpleasant catalyst. As limitations for this reception to consume place, the arene should be unsubstituted or should befool an activating meeting attached. such activating groups include: -OH, -OCH3, and -CH3 which depart extra rapport stabilization. Deactivating groups are electron withdrawing groups such as ?NO2. These withdrawing groups fail most of the age to station footfall to the stem this type of reception due to the leave out of resonance stabilization. In this chemical reception the arene p-xylene is the starting aromatic compound. In this typeface the p-xylene is more(prenominal)(prenominal)(prenominal)(prenominal) reactive than the starting bodily, n-propyl chloride and atomic public figure 13 chloride, so nonuple shifts no okie take place. The p-xylene is present in lavishness to prevent multiple alkylations of the reaction to take place. Rearrangements such as carbocation arrangements and methyl/hydride shifts git result in diametrical alkyl arenes as crossroads. The alkyl halides, with an exception to methyl and ethyl, belowgo these rearrangements. Usually, under the Friedel-Crafts alkylation conditions, basal alkyl halides rearrange to either secondary or tertiary carbocations that are a great deal more immutable. The reactant in this try out is n-propyl chloride. The products in this essay from the p-xylene are the unrearranged n-propyl group attached to the p-xylene (1,4-Dimethyl-2-n-propylbenzene) and the rearranged isopropyl group attached to the p-xylene (1,4-Dimethyl-2-isopropylbenzene). The aluminum chloride is the Lewis acid catalyst in the reaction and combines with the chloride ion of the n-propyl chloride to path the Friedel-Crafts complex. hitman chromatography will b e use to square off the three-figure produ! ct distri saveion of the resulting compounds. The purpose of this experiment is to carry out the Friedel-Crafts alkylation of p-xylene. alike the rearrangement of the primary alkyl group, n-propyl chloride, should be displayed. in the end the part composition of each product should be opinionated by the be adrift chromatography results. It is expected that the 1,4-Dimethyl-2-isopropylbenzene will be form at a greater percentage due to the more perpetual and thus faster isopropyl cation. The hydride shift speeds up the regale of this Friedel-Crafts alkylation reaction. response Equation:Experimental Section:A 25 mL cps permeate flaskful was weighed, recorded, and 7.4 mL of wry p-xylene was added. The exercising charge of the flask was thusly reweighed and the weight of the p-xylene was determined by subtraction. The enlarge bottom of the inning flask weighed 23.68 g. The round bottom flask with the p-xylene weighed 32.25 g, so therefore the p-xylene weighed 8.57 g to start (.081 moles). A charismatic tailspin bar was added to the flask. A Claisen adaptor was attached to the round bottom flask, with a rubber cap at the one go-ahead and a calcium chloride drying tube attached to the opposite end. stipendiary carful attention 0.31 g of anhydrous aluminum chloride was weighed out and added to the reaction flask quickly. The aluminum chloride was added to the reaction flask under the poser very quickly because of its reactive nature with the atmospheric moisture. A conical ampul was weighed and 2.7 mL of 1-chloropropane of the source Aldrich was added. The vial was past reweighed and the amount of 1-chloropropane was calculated. The initial weight of the vial was 26.78 g and the weight of the vial and the 1-chloropropane was 28.99 g. By subtraction, the 1-chloropropane was weighed and recorded as 2.21 g (.028 moles). The 1-chloropropane was whence added to the reaction flask drop wise with a syringe. The reaction flask wa s then left sit for an hour in contact with the stir! plate at means temperature. The motley in the reaction flask during this hour was an orangish/ lily-livered color. after the period of an hour, 8.0 mL of water was added to the reaction flask. The asset of the water resulted in smock smoke. The flask was unploughed on the stir plate until the aluminum chloride was completely consumed. The mixture was then transferred to a 125 mL separatory displace and the bottom aqueous layer was discarded. The top layer was a milky white color while the bottom layer was get througher precisely not completely translucent. This process was completed again. Instead 5% aqueous sodium bicarbonate firmness was added to the seperatory funnel shape. This solution was added to the funnel in order to get rid of any more water present. The same separation appearance as the footprint before was seen again. This process of separation was done at a time more with the profit of 6.0 mL of water added to the separatory funnel. After the lower aqueous layer was discarded, the rest of the solution was then transferred to a 25-mL Erlenmeyer flask. The flask was let sit for ten proceeding with occasional swirling, after(prenominal) 2.0 g of anhydrous sodium sulfate was added. The remain solution was then pipetted into a vial and a gas chromatogram of the product was obtained and analyzed. The same procedure was followed by a curse bookman with 2-chloropropane as the alkyl halide and the gas chromatogram was obtained and analyzed. GC results: (GC of starting substantial attached)ComponentRT (min)%AreaStandard 1-chloropopane0.55100.00Standard 2-chloropropane0.4641.650.5258.35Standard p-xylene0.591.071.0198.93Product w/ 1-Chloropropane Product w/ 2-chloropropaneThe data obtained from GC abstract of the products from the addition of 1-chloropropane were as follows:ComponentRT (min)%AreaComponent 10.610.73Component 21.0062.95Component 32.1315.31Component 42.3220. 996The data obtained from GC analysis of the products! from the addition of 2-chloropropane was as follows:ComponentRT (min)%AreaComponent 11.0363.38Component 22.1236.62The Gas Chromatogram showed different results for two of the different reactants used. The GC for the 2-chloropropane showed the retention timed of the reactant, p-xylene, and the 1,4-Dimethyl-2-n-propylbenzene product.

The GC for the 1-chloropropane that was used gave the retention multiplication of the reactant, p-xylene, the 1-chloropropane reactant and the two affirmable products of 1,4-Dimethyl-2-n-propylbenzene and 1,4-Dimethyl-2- isopropylbenzene. Discussion:The gas chromatograms show defini tive results. Comparing to the parameters of the p-xylene, 1-chloropropane, and 2-chloropropane the chromatograms of the resulting products were clear. For the GC of the reaction done with the 2-chloropropane there was a retention time of 1.03 for the p-xylene that matched up with the retention time of 1.01 of the supposition p-xylene. Also the retention time of 2.12 shown represents the 1,4-Dimethyl-2-isopropylbenzene that didn?t have to contact carbocation rearrangements with the 2-chloropropane as a reactant. The 1-chloropropane reactant chromatogram showed a retention time of 0.61 for the 1-chloropropane co-ordinated the 0.55 retention time of the given. The 1.00 retention time equals that of the given GC for the p-xylene. The two large retention times of 2.13 and 2.32 represent two of the products formed in this reaction with the 1-chloropropane as a reactant. some(prenominal) of the possible products showed up on this GC because of the carbocation rearrangement t o produce more stability. The primary alkyl halide o! f 1-chloropropane underwent a carbocation rearrangement to speed up the reaction. both(prenominal) the 1,4-Dimethyl-2-n-propylbenzene and the 1,4-Dimethyl-2-isopropylbenzene are delineated in this GC. The prediction of rearrangement was proven. Mechanism: erst generated by the reaction of n-propyl chloride and aluminum chloride, the resulting Friedel-Crafts complex can put up with a hydride shift, breaking the carbon-chlorine bond and forming an isopropyl cation. This cation will eventually be attacked by a retell bond from p-xylene. This forms a carbocation in the arene. The double bond is then reformed when the chlorine from the tetrachloroaluminate ion attacks the atomic number 1 on the carbon of the isopropyl group. Conclusion:Through experiment it was clear that the use of a different isomer of the reactant gave way to different products as seen with the help of the Gas Chromatogram. The process of Friedel-Crafts alkylation was carried out justly and the products of this reaction were well defined by the Gas Chromatogram results. The 1-chloropropane reactant, with electrophilic aromatic substitution gave way to the 1,4-Dimethyl-2-n-propylbenzene product and the rearranged 1,4-Dimethyl-2-isopropylbenzene. While the already stable carbocation once formed yielded the more stable product of 1,4-Dimethyl-2-isopropylbenzene. The rearrangement of the n-propyl chloride cation was displayed when the 1-chloropropane was used to form a more stable secondary carbocation product. References:MacKay, Elizabethtown College, department of alchemy and Biochemistry, A Friedel Crafts Alkylation. Modified 8/21/09O?Neil, Maryadele J. The Merck Index. fourteenth Ed. Merck & Co., Inc.: NJ, 2006. If you penury to get a full essay, order it on our website: OrderCustomPaper.com

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