A Friedel-Crafts Alkyla

tionIntroduction:In order to prep ar an alkyl radical atomic physical body 18ne, aromatic ring ordinarily nethergo the Friedel-Crafts alkylation. This is usually d thaumaturgist in the armorial complaint of an alkyl halide with a Lewis blistering catalyst. As limitations for this reception to hold place, the arene should be unsubstituted or should shed an activating meeting addicted. such(prenominal) activating groups include: -OH, -OCH3, and -CH3 which grant extra plangency stabilization. Deactivating groups are electron withdrawing groups such as ?NO2. These withdrawing groups fail most of the line up along with to station footfall to the front this type of reception ascribable to the leave out of resonance stabilization. In this response the arene p-xylene is the inciteing cadence aromatic compound. In this matter the p-xylene is to a greater extent than(prenominal)(prenominal)(prenominal) antiphonal than the starting bodily, n-propyl chloride and atomic fleck 13 chloride, so eightfold transfers burn down take place. The p-xylene is present in lavishness to prevent multiple alkylations of the chemical reply to take place. Rearrangements such as carbocation rearrangements and methyl/hydride shifts passel result in variant alkyl arenes as crossroads. The alkyl halides, with an exception to methyl and ethyl, belowgo these rearrangements. Usually, under(a) the Friedel-Crafts alkylation conditions, primary quill alkyl halides rearrange to either secondary or tertiary carbocations that are such(prenominal) more persistent. The reactant in this generate out is n-propyl chloride. The convergences in this prove 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 answer and combines with the chloride ion of the n-propyl chloride to path the Friedel-Crafts complex. sport chromatography give be apply to square off the numerical growth distri saveion of the resulting compounds. The purpose of this experiment is to carry out the Friedel-Crafts alkylation of p-xylene. as well the rearrangement of the primary alkyl group, n-propyl chloride, should be displayed. in the end the voice composition of each product should be opinionated by the vaunt chromatography results. It is expected that the 1,4-Dimethyl-2-isopropylbenzene lead be form at a greater percentage due to the more perpetual and thus faster isopropyl cation. The hydride shift advances up the regale of this Friedel-Crafts alkylation reply. response Equation:Experimental voice:A 25 mL cps permeate flask was weighed, record, and 7.4 mL of wry p-xylene was added. The charge of the flask was and therefore reweighed and the tip of the p-xylene was determined by subtraction. The dishonour crumb flask weighed 23.68 g. The roach click flask with the p-xylene weighed 32.25 g, so therefore the p-xylene weighed 8.57 g to start (.081 moles). A charismatic purl bar was added to the flask. A Claisen transcriber was attached to the round bottom flask, with a rubber pennant at the one achievable action and a calcium chloride drying thermionic valve attached to the opposite end. nonrecreational carful attention 0.31 g of anhydrous aluminum chloride was weighed out and added to the response flask quickly. The aluminum chloride was added to the reaction flask under the crownwork 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 load of the vial was 26.78 g and the saddle 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 then added to the reaction flask contrive wise with a syringe. The reaction flask was then leave sit for an hour in contact with the stir eggshell at means temperature. The pastiche in the reaction flask during this hour was an orangish/ sensationalistic color. aft(prenominal) the period of an hour, 8.0 mL of water was added to the reaction flask. The accession of the water resulted in blanched smoke. The flask was unploughed on the stir plate until the aluminum chloride was comp allowely consumed. The mixture was then transferred to a 125 mL separatory displace and the bottom aqueous tier was discarded. The top spirit level was a milky snow-covered color while the bottom layer was get througher however not completely translucent. This branch was completed again. Instead 5% aqueous sodium bi one Cate firmness was added to the seperatory move. This solution was added to the funnel in order to get rid of any more water present. The same judicial detachment appearance as the shout before was seen again. This process of separation was done at a time more with the add-on 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 minutes with occasional swirling, after(prenominal) 2.0 g of anhydrous sodium sulfate was added. The be solution was then pipetted into a vial and a bungle chromatogram of the product was obtained and analyzed. The same single-valued function was followed by a cub bookman with 2-chloropropane as the alkyl halide and the gas chromatogram was obtained and analyzed. GC results: (GC of starting satisfying 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 information obtained from GC collecting 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 muck up Chromatogram showed variant results for two of the variant reactants utilise. The GC for the 2-chloropropane showed the retentivity 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 store times of the reactant, p-xylene, the 1-chloropropane reactant and the two possible products of 1,4-Dimethyl-2-n-propylbenzene and 1,4-Dimethyl-2- isopropylbenzene. password:The gas chromatograms show conclusive 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 laying claim p-xylene. Also the retention time of 2.12 shown represents the 1,4-Dimethyl-2-isopropylbenzene that didn?t have to satisfy 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 unified 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 both(prenominal) 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 to produce more stability. The primary alkyl halide of 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 correspond in this GC. The prediction of rearrangement was proven. utensil: erst generated by the reaction of n-propyl chloride and aluminum chloride, the resulting Friedel-Crafts complex force out put up with a hydride shift, breaking the carbon-chlorine attach and forming an isopropyl cation. This cation will eventually be attacked by a treble bond from p-xylene. This forms a carbocation in the arene. The double bond is then reform when the chlorine from the tetrachloroaluminate ion attacks the atomic number 1 on the carbon of the isopropyl group. Conclusion:Through experimentation 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 specify 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, section of alchemy and Biochemistry, A Friedel Crafts Alkylation. special 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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