1. AbstractThis experiment implemented a Friedel-Crafts acylation in order to acylate anisole with acetic anhydride in the presence of anhydrous aluminum chloride and dichloromethane solvent. The acylation produced para- Methoxyacetophenone. The experiment implemented gentle reflux, extraction, rotovap, and H1 NMR/ IR spectrum analysis. The experiment yielded an oily, clear substance weighing 0.221 grams (14.7% recovery). The H1 NMR spectrum showed a 1:1 ratio between Ha and Hd, verifying the reaction took place; there were hydrogens present from both anisole and acetic anhydride in para- Methoxyacetophenone (methoxy and acyl group, respectively). The H1 NMR also showed only two types ...view middle of the document...
These activating groups direct ortho and para. Deactivating groups, on the other hand, are electron withdrawing; these groups remove electron density from the ring and direct to the meta position. These directing effects become clear in resonance structures. When activating groups are present, ortho and para attack exhibits a positive charge directly adjacent to the electron-donating group. The meta attack, however, does not exhibit this additional stability 2. When deactivating groups are present, electron density is removed from the ortho and para positions, and shows a lower energy in the meta position structures. In the case of the acylation performed in this experiment, a methoxy group is present, therefore directing the substitution to either ortho or para due to its inductive properties. Although there are two ortho positions, the para position is favored due to sterics; ortho attack exhibits more steric hindrance in the sigma complex than para attack, which is 1-4 addition 2.There are many differences and similarities among Friedel-Crafts acylations and alkylations. The main similarity between the two is they are both incompatible with electron withdrawing groups already present on the ring, due to deactivating effects. There are many more differences. First and foremost, Friedel-Crafts alkylations undergo methyl and hydride shifts in order to make more stable secondary and tertiary carbocations. Rearrangements do not occur in acylation, however, because it would result in loss of resonance stabilization 2. Alkylations also undergo polyalkylation, because of its activating effects. Polyacylation, however, does not occur because an acyl group is an electron-withdrawing group, and will deactivate the ring. Lastly, alkylations require catalytic amount of Lewis acids, whereas acylations require a stoichiometric amount.In this experiment, anisole was reacted with acetic anhydride in the presence of aluminum chloride and dichloromethane to yield one of the Friedel- Crafts acylation products, para- Methoxyacetophenone. Due to the presence of the methoxy group (activating group) on anisole, the resulting product could have been in ortho or para orientation. It was hypothesized, based on sterics, that the para product would be the predominate isomer. After a gentle reflux was run, the reaction was quenched over ice, the organic layer was separated, dried, and collected via rotovap. The isolated product was identified using H1 NMR and IR spectrum analysis.3. Experimental ProcedureBefore beginning the experiment, all glassware was washed and cleaned. After, the glassware was ovendried due to aluminum chloride's moisture- sensitive and highly corrosive properties. Then, the reflux apparatus was set up. The condenser was fitted with a Y-adapter in order to trap HCl gas produced during the reflux. One end of the Y-adapter was clasped, and the other end was attached to the HCl trap, which was an inverted funnel barely touching the surface o...
