The spin-reorientation transition, magnetic anisotropy, and first-order magnetization process (FOMP) of ${\mathit{R}}_{2}$${\mathrm{Fe}}_{14}$${\mathrm{BN}}_{\mathit{x}}$ compounds with R=Pr or Nd have been investigated by ac-susceptibility measurements from 4.2 to 300 K, the singular-point-detection technique in a pulsed-field facility in fields up to 30 T between 4.2 and 500 K and magnetization measurements in the Amsterdam High-Field Installation in fields up to 35 T and 4.2 K. It is observed that, compared to the corresponding ${\mathit{R}}_{2}$${\mathrm{Fe}}_{14}$B compounds, the anisotropy field, ${\mathit{B}}_{\mathit{a}}$, and the critical field of the FOMP, ${\mathit{B}}_{\mathrm{cr}}$, of ${\mathit{R}}_{2}$${\mathrm{Fe}}_{14}$${\mathrm{BN}}_{\mathit{x}}$ are dramatically reduced, whereas the spin-reorientation temperature ${\mathit{T}}_{\mathrm{SR}}$, of ${\mathrm{Nd}}_{2}$${\mathrm{Fe}}_{14}$${\mathrm{BN}}_{\mathit{x}}$ is only slightly decreased. These experimental data are analyzed in terms of the crystalline-electric-field interaction combined with the R-Fe exchange interaction.