- Synthesis of rodlike dispiro hydrocarbon skeletons for new liquid crystal compounds
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A simple synthesis of the dispiro[5.2.5.2]hexadecane skeleton was developed. Starting from the cyclohexanedicarbaldehyde 6 the dispirane was prepared in one step. The synthesised dispirodiketone 4 is a key compound for the preparation of a number of new l
- Feuerbacher, Nina,Voegtle, Fritz,Windscheidt, Jens,Poetsch, Eike,Nieger, Martin
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- Method of combined production of 1,4-cyclohexane dimethanol and cyclohexyl-1,4-diformaldehyde
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The invention relates to a method of combined production of 1,4-cyclohexane dimethanol and cyclohexyl-1,4-diformaldehyde and belongs to the technical field of chemical engineering synthesis. The method includes the steps of performing a reaction with dimethyl 1,4-cyclohexanedicarboxylate and hydrogen as raw materials under the effect of a catalyst, wherein molar ratio of H2 to ester is regulated to simultaneously prepare the 1,4-cyclohexane dimethanol and the cyclohexyl-1,4-diformaldehyde, wherein the catalyst is one or more selected from Ce, Cr, Cu, Mn, Zn and Zr; reaction temperature is 150-250 DEG C, reaction pressure is 2-6 MPa, the molar ratio of H2 to the dimethyl 1,4-cyclohexanedicarboxylate is 200-700; liquid space velocity of the dimethyl 1,4-cyclohexanedicarboxylate is 0.1-2.5/h; and the catalyst is one or more selected from Ce, Cr, Cu, Mn, Zn and Zr. The method has simple operations and low cost, and according to market demands, the products can be switched easily.
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Paragraph 0019; 0020; 0022; 0024; 0026; 0028; 0030; 0032
(2017/08/29)
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- Highly efficient transformation of alcohol to carbonyl compounds under a hybrid bifunctional catalyst originated from metalloporphyrins and hydrotalcite
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The development of a highly active and selective catalytic system that is economical, environmentally benign, and easily recoverable is highly desirable. Bifunctional hybrid catalysts originated from metalloporphyrins (MTSPP; M = Co, Fe, and Mn), and hydrotalcite have been synthesized, characterized, and investigated in the aerobic oxidation of alcohols in the presence of isobutyraldehyde. The designed catalysts exhibited excellent activity, broad applicable scope, and good stability in the oxidation. The effect of surface basicity on the catalytic performance has been studied in detail. The research results showed that as well as protecting the metalloporphyrin molecule, the surface basicity of hydrotalcite also contributed to improving the catalytic activity and the selectivity of aldehyde, and a synergistic effect was observed in the catalytic system. A proposed mechanism for the reaction involving the formation of high-valence cobalt-oxo porphyrin intermediate was postulated based on catalytic results and Hammett and H218O experiments.
- Zhou, Wei-You,Tian, Peng,Sun, Fu'An,He, Ming-Yang,Chen, Qun
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p. 105 - 116
(2016/01/26)
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- Conformational restraint in thermal rearrangements of a cyclobutane: 3,4-dicyanotricyclo[4.2.2.02,5]decane
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There being no study of a cyclobutane so fused to another cyclic system that an antiperiplanar conformation of the related diradical be precluded, the system in the title has been synthesized and studied for its thermal behavior. In comparison to the thermal behavior of unconstrained 1,2-dicyanocyclobutane in stereomutation and fragmentation to acrylonitrile, the constrained system shows a ~10-fold higher ratio of stereomutation to fragmentation to the three cis-1,4-bis-β-cyanovinylcyclohexanes. In these diolefins, a stereochemical correlation between the two olefinic fragmentation products is preserved. Revealed in the thermal rearrangement of isomer trans-1 is a surprising excess (78%) of cis-1-cis-β-cyanovinyl-4-transβ -cyanovinyl-cyclohexane, cis, trans-2, the result of zero internal rotations within the diradical-in-caldera prior to fragmentation (retention of configuration). Similarly, to a comparably striking extent, anti,cis-1 gives trans,trans-2 as its major product (71%), again by zero internal rotations.
- Doering, W. von E.,DeLuca, JoAnn Peters
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p. 10608 - 10614
(2007/10/03)
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- The competitive and non-competitive hydroformylation of conjugated dienes starting with tetrarhodium dodecacarbonyl. An in-situ high-pressure infrared spectroscopic study
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It is well known that the liquid-phase homogeneous unmodified rhodium catalysed hydroformylation of alkenes is poisoned by the presence of trace quantities of conjugated dienes. Nevertheless, some hydroformylation of conjugated dienes is possible with unmodified rhodium, and this reaction is in general slower than alkene hydroformylations at comparable reaction conditions. In the present contribution, we examined (A) the catalytic behaviour of alkenes in the presence of trace conjugated diene impurities and (B) the catalytic behaviour of a variety of dienes using Rh4(CO)12 in n-hexane solvent at 293 K under 1.0-4.0 MPa CO and 0.5-2.0 MPa H2. The analytic method was in-situ high-pressure infrared spectroscopy. It was observed that (I) in the hydroformylation of poisoned alkenes, most of the rhodium reacts with the trace quantity of conjugated dienes and not the alkenes in this competitive situation and (II) the metal carbonyl spectra of the hydroformylation of a variety of dienes are very similar. The primary absorbance maxima observed in the hydroformylations of conjugated dienes occur at circa 2109, 2091, 2087, 2064, 2049, 2037, 2030, 2020, 2012, 1999, and 1990 cm-1. Given the known chemistry Of Rh4(CO)12 under syngas, and the very well documented chemistry of Rh4(CO)12 under alkene hydroformylation conditions, the lack of bridging carbonyls in the present experiments strongly suggested that the new infrared vibrations are due to mononuclear rhodium species. Preliminary analysis suggests the presence of at least three new species. In particular, the formation of observable η3 allyl rhodium tricarbonyl species, σ allyl rhodium tetracarbonyl species and even acyl rhodium tetracarbonyl species RCORh(CO)4 (R = alkenyl and/or formylalkyl) seems probable. Characteristic wavenumbers of 2108, 2064, 2037, 2020 and 1700 cm-1 are tentatively assigned to the latter. The reduced hydroformylation activity in the competitive hydroformylation of alkenes arises due to the much higher affinity of rhodium complexes for conjugated dienes than for alkenes under otherwise similar reaction conditions.
- Liu, Guowei,Garland, Marc
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