The breakup reactions of 8B on a 12C target at 142, 285, 790, and 936 MeV/nucleon have been studied. One-proton-removal cross sections, leading to the production of 7Be fragments in the ground and first excited states (at 0.429 MeV), and the longitudinal momentum distributions of the 7Be fragments are obtained in the Eikonal approximation of the Glauber Model. The results of the calculations including the contribution of the 7Be to the ground and first excited states of 8B are compared with the available experimental data. One-proton-removal cross section for the 12C(8B, 7Be)X knockout reaction at 142, 285, 790, and 936 MeV/nucleon energy has been calculated. 8B and 7Be cross sections and momentum distribution are in a good agreement with available data.