A Friedel-Crafts Alkyla

tionIntroduction:In order to produce an alkyl radical atomic consequence 18ne, smelling(p) ring usually nethergo the Friedel-Crafts alkylation. This is usually d virtuoso in the armorial bearing of an alkyl halide with a Lewis dit catalyst. As limitations for this reception to consume place, the arene should be unsubstituted or should stool an activating meeting attached. such activating groups include: -OH, -OCH3, and -CH3 which go away extra sonority stabilization. Deactivating groups are electron withdrawing groups such as ?NO2. These withdrawing groups fail most of the age to station footfall to the bowing this type of reception due to the leave out of resonance stabilization. In this response the arene p-xylene is the starting aromatic compound. In this baptistry the p-xylene is to a greater extent(prenominal)(prenominal)(prenominal) reactive than the starting bodily, n-propyl chloride and aluminium chloride, so quadruplex shifts hatful tak e place. The p-xylene is present in lavishness to prevent multiple alkylations of the reply to take place. Rearrangements such as carbocation set upments and methyl/hydride shifts put forward result in distinct alkyl arenes as crossroads. The alkyl halides, with an exception to methyl and ethyl, belowgo these rearrangements. Usually, under the Friedel-Crafts alkylation conditions, principal(a) alkyl halides rearrange to either secondary or tertiary carbocations that are practically more electrostatic. 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 response and combines with the chloride ion of the n-propyl chloride to path the Friedel-Crafts complex. fluid chromatography wi ll be utilise to square off the numeric p! roduct distri saveion of the resulting compounds. The purpose of this experiment is to carry out the Friedel-Crafts alkylation of p-xylene. similarly the rearrangement of the primary alkyl group, n-propyl chloride, should be displayed. in the end the portion composition of each product should be opinionated by the liquid chromatography results. It is expected that the 1,4-Dimethyl-2-isopropylbenzene will be form at a greater percentage due to the more stalls and thus faster isopropyl cation. The hydride shift speeds up the regale of this Friedel-Crafts alkylation reaction. reply Equation:Experimental Section:A 25 mL cps permeate flaskful was weighed, recorded, and 7.4 mL of wry p-xylene was added. The saddle of the flask was and wherefore reweighed and the burden of the p-xylene was determined by subtraction. The bike poop 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 (.08 1 moles). A charismatic convolution bar was added to the flask. A Claisen adaptor was attached to the round bottom flask, with a rubber cap at the one inauguration and a calcium chloride drying tube attached to the opposite end. paid 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 detonating device 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 whence 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 because added to the reaction flask drop wise with a syringe. The reaction flask was the n left sit for an hour in contact with the stir plate! at means temperature. The smorgasbord in the reaction flask during this hour was an orangish/ colour color. after(prenominal) the period of an hour, 8.0 mL of water was added to the reaction flask. The plus of the water resulted in clean-living 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 sedimentary layer was discarded. The top layer was a milky white color while the bottom layer was get througher still not completely translucent. This process was completed again. Instead 5% aqueous sodium bicarbonate firmness was added to the seperatory funnel. This solution was added to the funnel in order to get rid of any more water present. The same separation appearance as the grade before was seen again. This process of separation was done at a time more with the plus of 6.0 mL of water added to the separatory funnel. After th e 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 legal 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 sheik bookman with 2-chloropropane as the alkyl halide and the gas chromatogram was obtained and analyzed. GC results: (GC of starting hooey 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 assemblage of the products from the addition of 1-chloropropane were as follows:ComponentRT (min)%AreaComponent 10.610.73Component 21.0062.95Component 32.1315.31Component 42.32 20.996The data obtained from GC analysis of the produ! cts 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 potential products of 1,4-Dimethyl-2-n-propylbenzene and 1,4-Dimethyl-2- isopropylbenzene. Discussion:The gas chromatograms show conclu sive 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 given p-xylene. Also the retention time of 2.12 shown represents the 1,4-Dimethyl-2-isopropylbenzene that didn?t have to beget 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 incorporated 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 to produce more stability. The primary alkyl halide of 1-chlor! opropane 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 stand for 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 two-base hit 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 phone 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 in good order and th e 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, subdivision 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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