Multistep synthesis - Multistep preparation of...

Multistep synthesis
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Multistep preparation of 4-bromo-2-chloro-6-iodoaniline Locker A-15 March 5, 2007 Monday 12:30-5:00 Step 1: Preparation of acetanilide Introduction : This is the first step in our synthesis of 4-bromo-2-chloro-6-iodoaniline. The first product to be synthesized is acetanilide from aniline. This is done by putting aniline into a hydrochloric acid solution. This would put the amine in equilibrium and then add acetic anhydride and sodium acetate to allow for the acetanilide functional group to substitute the amine group. Main Reaction: Data : Acetanilide Actual: Theoretical: Melting Point 101 ° -104 ° 114 ° Amount Collected 17.85 g 15.75g Summary of Procedure: We started out by mixing aniline and .4N of hydrochloric acid. We stirred the mixture and warmed it up. In another flask we prepared a solution of 6.0g of sodium acetate trihydrate in 20ml of water. In a third container, we put 4.4 ml of acetic anhydride. We then added the acetic anhydride to the anilinium hydrochloride then added the solution of sodium acetate immediately after. We then cooled the reaction and vacuum filtrated the acetanilide that was created. Observations : o The acetanilide came as a powder in a very moist state o There was a lot of acetanilide that was produced from the synthesis Results and Calculations: Acetanilide Percent Yield Amount Collected 100% Summary of results: By mixing anilinium hydrochloride with acetic anhydride and sodium acetate, we were able to successfully form acetanilide. Our percent yield for the acetanilide was actually
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more than 100% but it was only this high because it was still wet and the weight of the water had an effect on the mass. Since we don’t know the actual weight of the acetanilide, we must scale up for the next two steps to accommodate for the acetanilide. Post-Lab Questions: 20) The sodium acetate must be added quickly because the protonated ammonium species is a non-nucleophile because the lone pair of electrons on the nitrogen is not available. When acetic anhydride and amine hydrochloride are mixed, no acetylation occurs. The sodium acetate allows free amines to be liberated and allows acetic anhydride to react forming the acetylated product. 22) Aniline is soluble in aqueous hydrochloric acid because it has an NH2 group attached to the benzene ring that is a little bit more polar than the NHCOCH3 group on the acetanilide. This makes aniline soluble in hydrochloric acid and acetanilide insoluble. 25) IR of aniline: The NH parts of amines are in regions 3300-3000cm-1. This looks weaker than OH. These are sharp and distinguishable bands. The NH bending vibration of primary amines is seen in region 1650-1580 cm-1. Another region of amines is 910- 665 cm-1. The IR of acetanilide has a sharp peak around 3300. Step 2: Preparation of 4-bromoacetanilide
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