Conversion of isopropanol under supercritical conditions (400 °C, 11.0 MPa) on calcium and magnesium stannates MSnO3 (M = Ca, Mg) was studied. The main direction of the process is dehydrogenation of isopropanol to acetone, which then enters into the aldol condensation with selective formation of isomeric mesityl oxides. Products of hydrogenation of the C=C and C=0 bonds in mesityl oxide as well as products of isopropanol dehydration were also obtained. Under the experimental conditions, isopropanol is both a supercritical solvent and a source of hydrogen for hydrogenation of the multiple bonds. According to the results of diffuse reflectance infrared Fourier transform spectroscopy study using deuterated chloroform as a probe molecule, basic oxygen sites of the catalysts are of medium strength. During the conversion of isopropanol the more active catalyst MgSnO3 completely decomposes into the oxides MgO and SnO2 and the latter is then reduced to metallic tin, while the less active catalyst CaSnO3 is reduced slightly.

The results of a study of tandem reactions - aldol-crotonic condensation and hydrogenation by the mechanism of hydride transfer in acetone-isopropanol mixtures on a МgSnО3 catalyst at 300–400°C and 12.0 MРa are presented. In these conditions the mixture of reactants (acetone and isopropanol) and reaction products is in supercritical state. The temperature dependences of the reactants conversion and the selectivity for condensation and hydrogenation products are considered. It has been established that the hydrogenation of acetone aldol-crotonic condensation products proceeds by the addition of hydrogen from isopropanol molecule to C=O-bonds of isomeric mesityl and phorone oxides and is accompanied by dehydration of alcohols and isomerization of double C=C-bonds. The optimal conditions for the formation of the carbonyl group hydrogenation products are 350°C and the ratio acetone : isopropanol = 7 : 3. At the acetone to isopropanol ratio 1 : 1, methylpentadienes dominate in the products of mesityl oxide conversion. The hydrogenation reaction also proceeds with the participation of isophorones, the condensation products of three acetone molecules.

A series of 32 heterometallic ionic complexes [CeNi 6 (Ala) 12 ][(Ln x Ce 1 – x )(NO 3 ) 3 (OH) 3 (H 2 O)] (Ln = Tb, Ho, Er, Tm, Yb, Lu) have been synthesized and characterized by XRD and IPC-MS. The dependence of the degree of substitution of lanthanides in the anionic position on the nature of Ln 3+ and precipitation conditions has been determined. The processes occurring during the formation of the complexes have been studied by UV-Vis, diffuse reflectance electronic spectroscopy, and ICP-MS. Based on these data, a model of equilibria in the system was proposed to explain the increase in the degree of substitution of Ln in the anionic position in the lanthanide series and with a decrease in the concentration of Ce and Ln in the solution from which precipitation is performed.

Представлены результаты исследования тандемных реакций - альдольно-крото­новой конденсации и гидрирования по механизму гидридного переноса в смеси ацетон-изопропанол на катализаторе МgSnО3 при 300-400 °С и 12,0 МПа. При этих условиях смесь субстратов и продуктов реакции находится в сверхкритиче­ском состоянии. Рассмотрены зависимости от температуры степени превращения реагентов (ацетона и изопропанола) и селективности по продуктам конденсации и гидрирования. Установлено, что гидрирование продуктов альдольно-кротоновой конденсации ацетона протекает путем присоединения водорода от молекул изопропанола по С=О-связям изомерных оксидов мезитила и форонов и сопровож­дается реакциями дегидратации спиртов и изомеризации двойной С=С-связи. Оптимальные условия образования продуктов гидрирования карбонильной груп­пы - 350 °С и соотношение ацетон: изопропанол = 7 : 3. При соотношении ацетон: изопропанол = 1 : 1 в продуктах превращения оксида мезитила преоблада­ют метилпентадиены. Реакция гидрирования протекает также с участием изофо­ронов - продуктов конденсации трех молекул ацетона. The results of a study of tandem reactions - aldol-crotonic condensation and hydrogenation by the mechanism of hydride transfer in acetone-isopropanol mixtures on a МgSnО3 catalyst at 300-400 °C and 12.0 MРa are presented. In these conditions the mixture ofreactants (acetone and isopropanol) and reaction products is in the supercritical state. The temperature dependences of the reactants conversion and the selectivity for condensation and hydrogenation products are considered. It has been established that the hydrogenation of the acetone aldol-crotonic condensation products proceeds by the addition of hydrogen from isopropanol molecule to the C=O-bonds of isomeric mesityl and phorone oxides and is accompanied by the dehydration of alcohols and the isomeriza­tion of double C=C-bonds. The optimal conditions for the formation of the carbonyl group hydrogenation products are 350°C and the ratio acetone : isopropanol = 7 : 3. At the acetone to isopropanol ratio 1 : 1, methylpentadienes dominate in the products of mesityl oxide conversion.The hydrogenation reaction also proceeds with the participation of isophorones, the condensation products of three acetone molecules.

Синтезированы и охарактеризованы при помощи РФА и ИСП-МС 32 гетерометаллических ионных комплекса [CeNi 6 (Ala) 12 ][(Ln x Ce 1 – x )(NO 3 ) 3 (OH) 3 (H 2 O)] (Ln = Tb, Ho, Er, Tm, Yb, Lu). Определена зависимость степени замещения лантанидов в анионной позиции от природы Ln 3+ и условий осаждения. Процессы, протекающие в ходе образования изученных комплексов, исследованы методами ЭСП, ЭСДО и ИСП-МС. На основании этих данных предложена модель равновесий в растворе, объясняющая увеличение степени замещения Ln в анионной позиции по ряду лантанидов и при снижении концентрации Ce и Ln в растворе, из которого проводится осаждение.

The aldol condensation of acetone was carried out under the conditions of the supercritical state of the reagent (350 °C, 8 MPa; 400 °C, 12 MPa) on catalysts prepared by the thermal treatment of CaSn(OH)6 at 450 and 750 °C. The X-ray amorphous phase of CaSnO3 transforms into crystalline calcium stannate as the thermal treatment temperature increases from 450 to 750 °C. At 350 °C and 8.0 MPa, the selectivity of the reaction to mesityl and isomesityl oxides is about 85% (for both samples), but the conversion of acetone is much higher on CaSnO3 after it has been thermally treated at 750 °C. The reuse of the CaSnO3-450 catalyst led to its transformation. The conversion of acetone increases, and the reaction parameters (conversion and selectivity) reach values characteristic of CaSnO3-750. The catalyst structures were studied by XRD and scanning and high-resolution transmission electron microscopies.