text: At the initial stage of his research activity (1911-1917), V. G. Khlopin was mainly concerned with problems related to inorganic and analytical chemistry. In 1913, together with L. A. Chugaev, he worked on the synthesis of complex compounds of platonitrite with dithioethers. Of his further works, especially important are those aimed at the development of a new method for the preparation of various derivatives of univalent nickel, and the creation of a device for determining the solubility of compounds at different temperatures.
  To the most interesting works of this period belongs the discovery of hydroxopentamine series of complex compounds of platinum made in 1915 by L. A. Chugaev and V. G. Khlopin; curiously, but methodologically, from the point of view of the theory of cognition, it is quite natural that historically it was made somewhat earlier than the discovery by L. A. Chugaev and N. A. Vladimirov of the pentamine series, later called Chugaev's salts.
  Two works hold a special place in this period of V. G. Khlopin's scientific work:
  1. The action of hydrosulfur sodium salt on metallic selenium and tellurium, leading to the development of a convenient method of obtaining sodium telluride and selenide and a convenient synthesis of organic compounds of tellurium and selenium (1914),
  2. On the action of hydrosulfurosodium salt on nickel salts in the presence of nitrous sodium salt. The work led to the synthesis of univalent nickel derivatives (1915), which were much later (in 1925) obtained in Germany by S. Mansho and co-workers by the action of carbon monoxide and nitric oxide on nickel salts.
  Here, at the same department, already in the First World War, on the assignment of the Chemical Committee of the Main Artillery Department, V.G. Khlopin performed his first technological work - he developed a method of obtaining pure platinum from Russian raw materials. The importance of this work was due to the sharp reduction of imports. His participation in several expeditions aimed at identifying Russia's natural resources was subordinated to the solution of the same problems. He wrote reviews on rare elements: boron, lithium, rubidium, cesium and zirconium.