The reaction of \( 4 \)-methyloct-\( 1 \)-ene (\( P, 2.52 \, \text{g} \)) with \( \mathrm{HBr} \) in the presence of \( (\mathrm{C}_6\mathrm{H}_5\mathrm{CO})_2\mathrm{O}_2 \) gives two isomeric bromides in a \( 9:1 \) ratio, with a combined yield of \( 50\% \). Of these, the entire amount of the primary alkyl bromide was reacted with an appropriate amount of diethylamine followed by treatment with aq. \( \mathrm{K}_2\mathrm{CO}_3 \) to give a non-ionic product \( S \) in \( 100\% \) yield.
The mass (in \( \text{mg} \)) of \( S \) obtained is ________.
[Use: molar mass (in \( \text{g mol}^{-1} \)): \( \mathrm{H} = 1 \), \( \mathrm{C} = 12 \), \( \mathrm{N} = 14 \), \( \mathrm{Br} = 80 \) ]
