Br 2 Hbr Solution example essay topic

Relative Reactivity of AnilinesAbstract: Various Aniline were tested with Br 2/HBr solution, the products were crystallized and melting points attained to verify relative reactivity. My assignment, 2, 4-Dibromoanisol, was prepared in a yield of 52% with a melting point of 55-58 C. Reaction: Mechanism: Procedure: Anisole (0.35 mL, 0.0378 mol) was obtained and placed in a pre-weighed 25 mL round bottom flask, along with 2.5 mL of glacial acetic acid and a magnetic stir bar. Then the reaction apparatus was assembled, the dry tube was charged with conc. sodium bi sulfate, the 25 mL round bottom was attached to the apparatus, and 5 mL of Br 2/HBr mixture was obtained and placed in the round bottom. The reaction took place for 20 minutes.

An orange liquid was obtained and placed in a 125 mL Erlenmeyer flask along with 25 mL of water and 2.5 mL of conc. Sodium bisulfate son. The solution was then placed in an ice bath to precipitate and then the solid product was filter in a Buchner funnel. These crystals were then re-dissolved minimum amount of hot solvent (heptane) and recrystallized. Once a dry product was obtained, a melting point was established (2, 4-Dibromoanisol mp 55-58 C) and percent yield was established (52%). Results: Through a melting point reading, it was determined that the product obtained was 2, 4-Dibromoanisol mp 55-58 C. The products obtained by my partners, were determined to be: (p- mp 160-165 C) and (2, 4, 6, mp of 108-110 C) respectively.

Discussion and Conclusions: Interpreting these results have concluded that relative reactivity of these three aniline's in order of most reactive to least reactive go; Aniline Anisole Acetanilide. Aniline, has an NH 2, the most active substituent, and adds to any or tho / para position available on the ring. This data is confirmed with the product obtained, (2, 4, 6, mp of 108-110 C). As for anisole, it has a strongly activating group attached, OMe an group, and it added in two of the three available spots, both or tho. The results conclude: (2, 4-Dibromoanisol mp 55-58 C).

Acetanilide has a strong activating group attached, acyl amino group, but this group is large and the or tho positions are somewhat hindered so the majority of the product obtained added at the para position, results conclude: (p- mp 160-165 C). Since all the substituent's attached to the aromatic rings were activators the only products able to be obtained were or tho / para products. By comparing how many times bromine added to each of the aniline's we are able to interpret which were fastest, most reactive, and which were slowest. Since a halogen slightly deactivates the ring once attached, the activating group must be a strong one to continue to add more bromine.

Reactivity has been determined to be; Aniline Anisole Acetanilide. This method has proven to be a good way to test reactivities. Calculations: Percent yield: (02431 g/0.4685 g) 100 = 52% yield

Bibliography

Pavia, Donald L; Lamp man, Gary M; K riz, George S; Engel, Randall G", Introduction to Organic Laboratory Techniques, 2nd edition", Thompson Learning Inc. (c) 2005.
Carey, Francis A., "Organic Chemistry, fifth edition", McGraw Hill (c) 2003.