Abstract: The present invention relates to a steel for mold, containing: 0.28 mass %?C?0.65 mass %, 0.01 mass %?Si?0.30 mass %, 1.5 mass %?Mn?3.0 mass %, 0.5 mass %?Cr?1.4 mass %, 1.9 mass %?Mo+W/2?4.0 mass %, 0.2 mass %?V?1.0 mass %, and 0.01?N?0.10 mass %, with the balance being Fe and inevitable impurities, in which, in a state after quenching and tempering, the steel has: a (Mo, W) carbide having a diameter of 0.2 ?m or less being in an amount of 1.2 mass % or more, a ratio (mass ratio) of the amount of the (Mo, W) carbide to an amount of a Cr carbide being 11 or more, and a hardness change of 15 HRC or less.

Abstract: The present invention relates to a steel for mold, containing: 0.28 mass %?C?0.65 mass %, 0.01 mass %?Si?0.30 mass %, 1.5 mass %?Mn?3.0 mass %, 0.5 mass %?Cr?1.4 mass %, 1.9 mass %?Mo+W/2?4.0 mass %, 0.2 mass %?V?1.0 mass %, and 0.01?N?0.10 mass %, with the balance being Fe and inevitable impurities, in which, in a state after quenching and tempering, the steel has: a (Mo, W) carbide having a diameter of 0.2 ?m or less being in an amount of 1.2 mass % or more, a ratio (mass ratio) of the amount of the (Mo, W) carbide to an amount of a Cr carbide being 11 or more, and a hardness change of 15 HRC or less.

Abstract: This invention provides a process for producing 3'-deoxy-'-fluorothymidine, which comprises allowing 3'-deoxy-'-fluoro-5'-mesylthymidine (the stating material) to react with an acetylating agent, selected from the group consisting of alkali metal salts of acetic acid, amine salts of acetic acid and ammonium acetate, in an aprotic, ploar solvent to form the 5'-acetyl derivative, and ammonium acetate, in an aprotic, polar solvent to form the 5'-acetyl derivative, and eliminating the 5'-acetyl group from this intermediate, thereby giving the objective 3'-deoxy-'-fluorothymidine.According to the process of this invention described above, the 5'-mesyl derivative can be efficiently acetylated, and 3'-deoxy-'-fluorotymidine can be obtained in a high yield.