Synthesis and structure determination of amines

Exercise 4

$3.75\;g$ of a chiral monoamine $A$ is dissolved in water so as to obtain $500\;mL$ of solution. A volume of $20\;mL$ of this solution is titrated with $ 0.1\;M $ hydrochloric acid. The indicator color change occurs when there are introduced $V$ $=$ $20.5\;cm^3$ acid. 1) Calculate the molar mass of A. 2) Action of iodomethane leads to a mixture of secondary amine, tertiary amine and quaternary ammonium salt. Give the structural formula of $A$. 3) Write the semi-developed formulas of products obtained during the action of iodomethane .

1) Titration: $n_A$ $=$ $n_{HCl}$ $=$ $0.1\cdot 0.0205$ $=$ $0.00205$ $m_A$ $=$ $\frac{3.75\cdot 20}{500}\; g$ $M_A$ $=$ $\frac{3.75\cdot 20}{500\cdot 0.00205}$ $\approx$ $73 \frac{g}{mol}$ 2) General formula: $C_xH_yN$ $12x$ $+$ $y$ $+$ $14$ $=$ $73$ $12x$ $+$ $y$ $=$ $59$ Only reasonnable possibility: $x$ $=$ $4$ $;$ $y$ $=$ $11$ Molecular formula: $C_4H_{11}N$ $A$: $CH_3CH_2C^*H(CH_3)NH_2$ 3) $CH_3CH_2C^*H(CH_3)NH(CH_3)$ $CH_3CH_2C^*H(CH_3)N(CH_3)_2$ $CH_3CH_2C^*H(CH_3)N^+(CH_3)_3\; I^-$