EN
We consider the problem of constructing the optimal closed loop control in the time minimal control problem, with terminal constraint belonging to a manifold of codimension one, for systems of the form $v̇ = X + uY$, $|u| ≤ 1$ and $v ∈ R^2$ or $R^3$, under generic assumptions. The analysis is localized near the terminal manifold and is developed to control a class of chemical systems.