Question

For the bromination of trans-cinnamic acid, provide two reasons as to why pyridinium bromide perbromide is the brominating agent of choice as opposed to elemental bromine.

Convert 16.5 mmol pyridinium bromide perbromide to grams

Convert 300 mmol glacial acetic acid to mL.

Answer 1

Since pyridinium bromide perbromide, C₆H₆NBr.Br₂ is a relatively stable red crystalline compound having a melting point of 135.6 degree celcius.

There are no annoying fumes to contend with during handling,no elaborate apparatus is necessary for weighing out the required amounts of pyridinium bromide perbromide

when spilled it can be easily brushed off clothing, hands, or face with no accompanying danger of burns while bromine is dangerous and not safe for use of students.

Conversion of  16.5 mmol pyridinium bromide perbromide to grams

we know that

number of moles=weight(gram)/molecular weight .

weight=0.0165*319.82

where molecular mass=319.82 g/mol

w=5.2767 gram

Convert 300 mmol glacial acetic acid to mL.

molecular weight of glacial acetic acid is 60.05 g/mol

here number of moles are 0.3 mol

therefore w=60.05*0.3

w=18.015 gram

now density= mass/volume

volume = mass/density

=18.015/1.049

= 17.179 ml