Question

2. Tribromide ion (in the form of the pyridinium tribromide salt) is used because it is far safer than using elemental bromine. Look up the MSDS information online for both elemental bromine and pyridinium tribromide and highlight some noticeable safety differences. 3. Show the mechanism and product of the reaction of trans-pent-2-ene with elemental bromine. Include stereochemistry in your intermediates and answer. Is the product meso?

Answer 1

Answer 3: Reaction of elemental bromine with alkene is addition of bromine to C=C. Addition of halogen to carbon -carbon double bond occur through anti-addition and hence trans-pent-2-ene gives meso compound as shown in figure below.

(2R,3S)-2,3-dibromopentane Cals Br. HC Br. НаС Br Calls С-НS meso НзС Н Н С Н Br Н Br Br b НЕС—С— Br Н (2S,3R)-2,3-dibromopentane

Answer 2: According to MSDS information. Exposure to pyridinium tribromide cause eye burns and skin burns while bromine vapors cause eye burns with lachrymator and eye injury. It may also cause permanent corneal opacification. Contact with liquid bromine is corrosive and causes severe skin burns and ulceration. It may also cause measle-like eruptions. Pyridinium tribromide causes gastrointestinal tract and respiratory tract burns however bromine if inhaled may be fatal in addition to tract burns.