Nachfolgend noch eine weitere angepasste Lösung.
\documentclass{article}
\usepackage{chemfig}
\setchemfig{atom sep = 2.3em,
cram width = 4.5pt
}
\renewcommand*\printatom[1]{\ensuremath{\mathsf{#1}}}
%
\begin{document}
\thispagestyle{empty}
\schemestart
\chemfig{H_3C-C(-[:90]CH_3)(-[:-90]CH_3)-@{1}\charge{90:1pt=\:,-90:1pt=\:}{O}-[:-40]H}
\arrow{0}[,0.1] + \arrow{0}[,0.25]
\chemfig{@{4}\charge{0:2pt=$\scriptstyle{\oplus}$}{O}(-[:70,.9,,,line width=3pt,dash pattern=on 0.8pt off 2pt]H)(<[@{3}:110]@{2}H)-[:-90]H}
\arrow{->[][--$\,\mathsf{H_2O}$][1pt][]}[,1.2,-Latex]
\chemfig{H_3C-C(-[:90]CH_3)(-[:-90]CH_3)-\charge{-90:1pt=\:,90:3pt=$\scriptstyle{\oplus}$}{O}(-[:40]H)-[:-40]H}
\schemestop
%
\chemmove{\draw[shorten >=5pt, shorten <=2pt] (2).. controls +(135:1cm)and+(90:1cm)..(1);}
\chemmove{\draw[shorten >=2pt, shorten <=5pt] (3).. controls +(180:0.4cm)and+(west:.75cm)..(4);}
\end{document}
