10 results about "Dihydroxylation" patented technology

This invention discloses a method for preparing a key intermediate of iodopyridine, using dimethyl malonate as a raw material, and sequentially undergoing dihydroxylation S1 → acetalization S2 → hydrolysis and acidification S3 → decarboxylation S4 to obtain iodopyridine. The raw materials of this invention are inexpensive and readily available in the market, and the reaction efficiency is high, improving the purity and yield of the product. Intermediates 1 and 2 obtained from the process do not require separation and purification operations and can be directly used in the next step of the reaction. The purification effect is significant, yielding intermediate products with a purity ≥99%, and the total yield of the five steps is as high as 65-70%, which is beneficial for large-scale production.

Methods for asymmetric cis-dihydroxylation ("AD") of quinones to produce cis-diols of quinones with high yield (i.e. a yield ≥ 30%) and high enantioselectivity (i.e. an enantiometric excess ≥ 30%) are disclosed. The method uses an iron-based catalyst, such as one or more Fe(II) complexes, as the catalyst, and can be performed under mild reaction conditions (e.g. a temperature ≤ 50°C at 1 atom in open air). The method generally includes: (i) maintaining a reaction mixture at a temperature for a period of time sufficient to form a product, where the reaction mixture contains a quinone, one or more iron-based catalyst (s), and a solvent, and where the product contains a chiral cis-diol. Optionally, the method also includes adding an oxidant into the reaction mixture prior to and / or during step (i), such as a hydrogen peroxide solution.

The invention relates to the field of carbonate polymerization, and discloses isosorbide polycarbonate and a preparation method thereof. The preparation method of the isosorbide polycarbonate comprises the following steps: under the action of a ketonic acid metal salt catalyst, taking a dihydroxy compound, diester carbonate and aliphatic dihydric alcohol as raw materials, and carrying out transesterification and polycondensation reaction to obtain the isosorbide polycarbonate. The keto acid metal salt is used as the catalyst for synthesizing the isosorbide polycarbonate, the catalyst is low in price and not prone to inactivation, and the isosorbide polycarbonate with high molecular weight and ideal transparency is catalytically synthesized.

The present invention provides an estetrol synthesis process, and relates to the technical field of steroid compound synthesis processes, and the method comprises the following steps: taking estrone as an initial raw material, firstly carrying out 3-site hydroxyl protection, and then carrying out an oxidative dehydrogenation reaction in the presence of a metal catalyst and in an oxygen atmosphere to prepare a key intermediate ketene, then 17-site carbonyl reduction, 17-site hydroxyl protection, 15, 16-site double bond dihydroxylation, 3-site protecting group removal and hydrolysis reaction are sequentially carried out, and finally the target product estetrol is obtained. The method adopts metal catalysis to directly oxidize to construct cycloenone, effectively avoids the problem of poor stability of partial intermediates in the prior art, has the advantages of simple process, short reaction steps, greenness, environmental protection and the like, and is suitable for industrial production.

The present invention addresses the problem of providing a composition containing a dihydroxy compound having a biphenanthrene skeleton, the composition making it possible to diminish troubles caused by metals remaining in large amounts in conventional dihydroxy compounds having a biphenanthrene skeleton. This composition contains a dihydroxy compound having a biphenanthrene skeleton, the dihydroxy compound being represented by general formula (1a) and having a total content of sodium, potassium, iron, and copper metals of 40 ppm or less. (In the formula, the R1 moieties each independently represent a C2-C4 alkylene group, the R2 moieties each independently represent a C1-C6 alkyl group, a C6-C18 aryl group, or a halogen atom, and each n independently indicates 0 or an integer of 1-4.)

This polycarbonate diol contains a structural unit (1) represented by general formula (I) and a structural unit (2) represented by general formula (II). The percentage content of the structural unit (2) in the polycarbonate diol is 4.3 mol% or less relative to the total structural units of the polycarbonate diol which is 100 mol%.　The present invention can provide: a method for producing a polycarbonate diol, in which a diol such as 1,4-butanediol is used as a raw material and a polycarbonate diol with a molecular weight close to the theoretical molecular weight in high yield can be obtained; and a polycarbonate diol that makes it possible to obtain a polyurethane having excellent mechanical properties and chemical resistance and configured to suppress variation in the mechanical properties.　In general formula (I), n is an integer of 4-6. Also, in general formula (II), m is an integer of 2-4.

A highly efficient synthesis of cis-diol compounds through cis-dihydroxylation of olefins using osmate (VI) salt as catalysts is disclosed, which has found important application in efficient large-scale preparation of, among others, α,α-cedranediol from α-cedrene.

The present invention relates to a process for manufacturing a polycarbonate comprising the steps of: i) melt reacting a dihydroxy compound and a carbonate, optionally in the presence of one or more transesterification catalysts, thereby forming a stream of molten polycarbonate, i ') combining the stream of molten polycarbonate obtained in step i) with 0 to 5000 ppm of water, based on the weight of polycarbonate, ii) feeding the stream of molten polycarbonate obtained in step i) or step i') to a melt mixing device, iii) combining the stream of molten polycarbonate with 0 to 5000 ppm of water, based on the weight of polycarbonate, in the melt mixing device, ii) feeding the stream of molten polycarbonate obtained in step i) to the melt mixing device, iii) combining the stream of molten polycarbonate and 0 to 5000 ppm, based on the weight of polycarbonate, of water in the melt mixing device, the total amount of water to be combined with the stream of molten being 5 to 5000 ppm, based on the weight of polycarbonate, iv) subjecting the stream obtained in step iii) at least partially to a vacuum in the range of 1 to 800 mbar, and v) passing the stream obtained in step iv) through a melt filter in order to at least partially remove water from the stream of molten polycarbonate, and v) passing the stream obtained in step iv) through the melt filter.

The invention relates to a method for producing a polycarbonate, comprising the steps of:-subjecting a dihydroxy compound and a carbonate to a melt reaction, optionally in the presence of a transesterification catalyst, thereby forming a molten polycarbonate stream, and-combining the molten polycarbonate stream with 5 to 5000 ppm of water and 50 to 10000 ppm of a siloxane compound, based on the weight of the polycarbonate.

The present invention relates to a process for manufacturing a polycarbonate comprising the steps of i) melt reacting a dihydroxy compound and a carbonate, optionally in the presence of a transesterification catalyst, thereby forming a stream of molten polycarbonate, ii) passing the stream of molten polycarbonate obtained in step i) through a melt filter, iii ') combining the filtered stream of molten polycarbonate obtained in step ii) with 0 to 5000 ppm of water, based on the weight of polycarbonate, iii) feeding the stream obtained in step ii) to a melt mixing device, and iv) combining the stream of molten polycarbonate obtained in the melt mixing device with 0 to 5000 ppm of water, based on the weight of polycarbonate, wherein after combining the stream of molten polycarbonate with said water, the stream is subjected to a vacuum wherein the total amount of water to be combined with the stream of molten polycarbonate in steps iii ') and iv) is from 5 to 5000 ppm based on the weight of polycarbonate.