  We present work in a model used to describe semi-inclusive deep inelastic
scattering off the deuteron. The model uses the virtual nucleon approximation
to describe the interaction of the photon with the bound neutron and the
generalized eikonal approximation is applied to calculate the final-state
interaction diagram. Comparison with data taken at Jefferson Lab shows good
agreement in the covered range of kinematics and points at a largely suppressed
off-shell rescattering amplitude. The $W$ and $Q^2$ dependences of the total
cross section and slope factor of the interaction of DIS products, $X$, off the
spectator nucleon are extracted. Starting from the JLab data and our model
calculations, we outline and apply an extrapolation method to obtain the
neutron structure function $F_{2N}$ at high Bjorken $x$.
