ADDkid
(Hive Bee) 06-25-04 16:11 No 515438 |
Hofmann rearrangement? | |||||||
I know this is a stupid question, however I tried the search engine. If a strong sodium hydroxide solution is added to sodium bromide would that form the hypobromite that is needed for the Hofmann reaction. I was unsure if the molar ratios of the Na ions needed to be equal? Does the bromine Lewis acid need to be present. And if so would HBr be a better choice when it is neutralized with Hydrogen peroxide, and then slowly added Sodium hydroxide to the solution? |
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WizardX (Wizard Master) 06-25-04 18:47 No 515472 |
hypobromite | |||||||
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ADDkid (Hive Bee) 06-25-04 20:26 No 515483 |
Wizard you should have read the whole post, I... | |||||||
Wizard you should have read the whole post, I mention that adding hydrogen peroxide to HBr until neutral, and then adding the NaOH, I don't believe that the soultion needs to be concentrated so the water that is formed from adding the peroxide should not matter. |
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WizardX (Wizard Master) 06-26-04 17:47 No 515645 |
Temperature | |||||||
ADDkid: NaOBr is temperature sensitive. Lets take a closer look at the procedure marked in red. 2 NaOH + Br2 ==> NaOBr + NaBr A solution of 42 g. (1.05 moles) of sodium hydroxide in 360 ml. of water is placed in a 1-l. three-necked, round-bottomed flask fitted with a mechanical stirrer and a thermometer and is cooled to -5° in an ice-salt bath. The stirrer is started, and 43 g. (0.263 mole) of bromine is added from a separatory funnel at such a rate that the temperature remains below 0° (addition time about 5 minutes). The ice-cold solution is diluted with 240 ml. of dioxane (Note 1) that has previously been cooled to 13–14° (Note 2). This solution is kept at 0° until required. 2. The temperature of the hypobromite solution is kept below 10° to avoid the formation of sodium bromate.
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