#"HBr"# reacts with propene in the presence of organic peroxides by a free radical mechanism to give an anti-Markovnikov addition product.
The steps are:
Initiation: #"RO-OR → 2RO·"#
Initiation: #"RO·" + "H-Br" → "RO-H" + "Br·"#
Propagation: #underbrace("CH"_3"CH=CH"_2)_color(red)("propene") + "Br·" → "CH"_3 stackrelcolor(blue)(bb·)("C")"H-CH"_2"Br"#
Propagation: #"CH"_3 stackrelcolor(blue)(bb·)("C")"H-CH"_2"Br" + "H-Br" → underbrace("CH"_3"CH"_2"CH"_2"Br")_color(red)("1-bromopropane") + "Br·"#
The product is 1-bromopropane.
Primary alkyl halides react with aqueous silver nitrite in an #"S"_"N"2# displacement to form primary nitroalkanes.
Thus,
#"CH"_3"CH"_2"CH"_2"Br" + "Ag-O-"stackrelcolor(blue)(. .)("N")"=O" → underbrace("CH"_3"CH"_2"CH"_2"NO"_2)_color(red)("1-nitropropane") + "AgBr"#
The product is a nitro compound and not a nitrite because the #"Ag"# is covalently bound to the #"O"#.
Thus, it is the lone pair on the #"N"# that attacks the α-carbon of the bromide.
