Question

Chern 204-PSI, 6 . Friedel Crafts Acylation of an Unknown Benzene Compound (One weck lab The Intent of this Lab To acetylate an unknown benzene compound via a Friedel-Crafts acylation and use spectroscopic techniques to determine the acetophenone derivative's identity Introduction The Friedel-Crafts reaction dates back to before 1900 and it is still widely used today. The active electrophilic agent (an acylium ion) is classically prepared and reacts very quickly. Another appealing feature of this reaction is that the acylated product is less reactive than the starting material and so polysubstitution is not a problem. We try to give you aromatic unknowns with an a-carbon not always be the case and, of course, one has to be careful with the chloride compounds for obvious reasons. atom (mostly eliminates carcinogenicity) but this may Part A Experimental- Generation of Acylium Ion Given і.5mL AICI (0.73 g pre-weighed), acetyl chloride (1 eq). dry CH C A lab with glassware, organic and inorganic compounds Useful hints. Present the written group plan to your instructor that describes how to generate the acylium ion. The chlorides are both very very water sensitive and release nasty gases. Act accordingly Set up a suitably sized apparatus. The AlCh is a solid so put it in the RBF first then inject solvent. Over 5 min, inject the acetyl chloride (CH COCI) (in 1 ml of solvent) to the AICl, (in 1.5 ml of Objective: Hints: solvent) Incidentally, this mixture tends to decompose at room temperature. Actions? Experimental - EAS (Electrophilic Aromatic Substitution) Part B Given: Unknown (0.91 eq. pre-weighed), ice (5 g). conc. HCI (1.5 mL.). NaHCO, (sat.) Objective: Present a written plan from your group which explains how the unknown will be reacted, worked up and isolated Over 5 min, add the unknown (in 1 ml. of dry CH-Cl:) to the reaction. Use the same syringe Now allow it to reach room temperature and keep it at this temp. for 15 minutes. Quench the reaction by pouring it into an ice-HCI mixture. Note the order! Isolate the organic layer by itself and extract the aqueous layer with solvent. Combine the product-containing layers and get rid of an acidic impurity Hints: In fact repeat this process once more and then isolate the procduct layer 61

Answer 1

Friedel crafts Acylation implies when a Benzene is treated with acyl chloride in the presence of suitable acid (such as Lewis acid. A(cl_3) FeCl_3, BCl_3) Electrophilic substitution reaction of acyl group occur at the Benzene Ring this is known as friedel craft Acylation mechanism implies step I implies Generation of Electrophilic step - II Attack of Electrophilic one C_6 H_6 step - III proton Abstraction and Aromatization of the Benzene Ring \r\n Addition of a very small amount of water to AlCl_3 can dramatically change the nature of there catalysts promoters, pure anhydrous aluminum chloride are purely Lewis Acid however small amount of water creates a mixed Bronsted/Lewis acidic system, which can promote the following Reaction of Benzene with Anlydrous AlCl_3 and chloroform. It is a friedel - crafts Alkylation. And the result will be methylation of the benzene Ring. You will find that the aluminium chloride acts to remove a chloride can from the CHCl_3, turning into a good Electrophilic