45 results about "Pentanone" patented technology

A preparation method of N '-((2S, 3S)-2-(benzyloxy) pent-3-yl) formylhydrazine oxalate enzyme belongs to the field of medical intermediates, and comprises the following steps: step 1, preparing a buffer solution of a compound enzyme preparation; step 2, adding (2S)-2-benzyloxy-3-pentanone into a solvent A, and then adding a buffer solution of the compound enzyme preparation for reaction; 3, filtering, and carrying out an activation reaction on the filtrate; 4, filtering, removing the solvent, adding the obtained solid into a solvent B, and then adding formylhydrazine for reaction; 5, filtering, removing the solvent, adding the obtained solid into a solvent C, and then adding oxalic acid for reaction; and 6, drying the solid obtained by filtering to obtain the N '-((2S, 3S)-2-(benzyloxy) pent-3-yl) formylhydrazine oxalate. According to the method, the yield of the N '-((2S, 3S)-2-(benzyloxy) pent-3-yl) formylhydrazine oxalate can be increased, and the production cost is effectively reduced.

This invention discloses a method for producing 4-methyl-2-pentanone, which is implemented using a 4-methyl-2-pentanone production apparatus. The apparatus includes a reactive distillation column, a condenser connected to the top of the reactive distillation column, and a reboiler connected to the bottom of the column. The reactive distillation column has a rectification section, a reaction section, and a stripping section arranged sequentially from top to bottom. During operation, a catalyst is placed in the reaction section, and 4-methyl-2-pentanol is introduced into the reaction section. The temperature of the reaction section is controlled at 180–280°C. The gas phase produced by the reaction is condensed by the condenser to produce 4-methyl-2-pentanone. This production method features high conversion rate, stable product quality, and low energy consumption.

This invention relates to "an efficient and safe method for synthesizing perfluoropentanone," belonging to the field of organic chemical synthesis. The method for synthesizing perfluoropentanone is characterized by the following steps: under the action of hexafluoropropylene CF2=CF-CF3, fluorophosgene CF2O, and trifluorobromomethane CF3Br, perfluoropentanone (C5F) is generated in the gas phase. 10 O. The raw materials of this invention are inexpensive and readily available; the product separation and purification are simple; it is easy to industrialize; and it produces less industrial waste.

The application discloses a preparation method of an amido pyrazole compound and a method for preparing sildenafil by using the same. The amido pyrazole compound is shown as formula I. The compound of formula I is prepared by using 2-pentanone as an industrial chemical, and can be used for synthesizing sildenafil which is a selective inhibitor of type 5 phosphodiesterase (PDE5). The method has the advantages of easy availability of raw materials, simple operation, avoidance of nitration reaction, avoidance of safety hidden dangers caused by the nitration reaction from a technical source, and avoidance of environmental protection pressure caused by a large amount of nitration waste liquid, and is suitable for development into a green and sustainable production process of sildenafil bulk drug.

The application relates to the technical field of alpha-olefin preparation, and discloses a method for preparing 4-methyl-1-pentene from 4-methyl-2-pentanone, which comprises the following steps: (1) mixing 4-methyl-2-pentanone with hydrogen in the presence of a hydrogenation catalyst to perform a hydrogenation reaction, so as to obtain a 4-methyl-2-pentanol-containing stream; (2) performing ketone removal on the 4-methyl-2-pentanol-containing stream, so as to obtain 4-methyl-2-pentanone and 4-methyl-2-pentanol crude products; and (3) performing dehydration reaction on the 4-methyl-2-pentanol crude products obtained in the step (2) in the presence of a dehydration catalyst, so as to obtain a 4-methyl-1-pentene-containing stream. The method for preparing 4-methyl-1-pentene from 4-methyl-2-pentanone can be simply and effectively used for preparing 4-methyl-1-pentene products, 4-methyl-2-pentanone raw materials are easy to obtain, the reaction conditions are relatively mild, the product distribution is simple, and high-purity 4-methyl-1-pentene products can be prepared.

The invention relates to a method for a palladium-catalyzed cyclization extension reaction of butadienes. Specifically, under the condition that tert-butyl nitrite is oxidized under the catalysis of palladium, the cyclopentanone compound is obtained through a ring extension reaction of butyl fulvene and water. According to the invention, green and rich water is used as a raw material, and a series of cyclopentanone compounds are obtained under mild conditions.

The application belongs to the technical field of organic chemical synthesis and heterogeneous catalysis, and particularly relates to a catalyst for preparing 2,4-dimethyl-3-pentanone from isobutyric acid or isobutyric anhydride and a preparation method thereof. The application overcomes key technical bottlenecks in the existing gas-phase ketonization reaction, such as serious cracking side reactions, quick deactivation of the catalyst due to carbon deposition, and low selectivity of the target product. The application provides a method for efficiently preparing 2,4-dimethyl-3-pentanone from isobutyric acid or isobutyric anhydride. The method innovatively constructs a modified HZSM-5 molecular sieve catalyst with a micropore-mesopore multi-level pore structure, and introduces specific metal oxide active components to construct acid-base synergistic active centers, thereby realizing directional regulation of the reaction path. The method not only significantly inhibits the competitive monomolecular cracking reaction, greatly improves the selectivity of the bimolecular coupling ketonization reaction for generating 2,4-dimethyl-3-pentanone, but also effectively eliminates the diffusion resistance of macromolecular products by using mesoporous channels, thereby fundamentally solving the problem of easy carbon deposition and deactivation of the catalyst, and having excellent industrial application prospects and technical progress.

The invention belongs to the technical field of organic synthesis, and provides a method for synchronously preparing 3-methyl-2-butanone and 3-pentanone, butanone, methanol, ion exchange resin and a catalyst are mixed for alcohol ketone condensation reaction, and 3-methyl-2-butanone and 3-pentanone are obtained at the same time. Methanol and butanone are used as raw materials and react under the action of ion exchange resin and an activated carbon supported metal catalyst. According to the method, directional control of the molar ratio of 3-methyl-2-butanone to 3-pentanone is realized by accurately regulating and controlling reaction conditions, and generation of other by-products in the reaction process is relatively low. Specifically, when anion exchange resin is added into reactants, alpha-H at the edge of butanone is strong in acidity and small in steric hindrance, so that 3-pentanone is a main product (selectivity is greater than or equal to 75%); when cation exchange resin is added into reactants, alpha-H in butanone is good in stability, and 3-methyl-2-butanone is a main product (selectivity is greater than or equal to 70%).

According to the method for recovering the PGME and the PGIE from the HPPO process wastewater, the HPPO process wastewater is concentrated through the membrane separation device, the content of the PGME and the PGIE in the wastewater is greatly increased, and compared with the prior art, the energy consumption can be greatly reduced, the recovery efficiency can be improved, and the recovery cost can be reduced; 2-pentanone or 3-pentanone and a mixture of 2-pentanone and 3-pentanone are used as an azeotropic solvent to replace benzene, and the solvent circulation amount in the dehydration process can be reduced by 50% under the same pressure, so that the dehydration energy consumption is remarkably reduced, and the green and environment-friendly process requirements are met; the water layer of the dehydrated fraction is recycled into the HPPO process wastewater and then is subjected to membrane separation, so that the loss of trace PGME entrained in the dehydrated fraction can be avoided, and the yield of the PGME is increased; according to the technical scheme, the recovery rates of the PGME and the PGIE can reach 99%.

The application relates to a synthesis method of 2-hydroxy-2-methylcyclopentanone compounds and belongs to the technical field of organic synthesis. The 2-hydroxy-2-methylcyclopentanone compounds are prepared from cyclobutanone compounds through protection of carbonyl groups, deprotection and rearrangement reaction; the application does not need to use expensive metal catalysts, has mild reaction conditions, does not need high-pressure equipment, is high in safety and easy to be industrialized, is high in atomic economy, is simple in operation, avoids use of highly toxic or high-pollution reagents, and is low in mercury salt consumption.

This invention belongs to the field of ketoxime synthesis technology and provides a method for synthesizing 3-pentanone oxime. The method uses 3-pentanone, hydrogen peroxide, and ammonia as raw materials, adds a catalyst, and reacts in a closed system. After the reaction, the mixture is filtered and distilled under reduced pressure to obtain 3-pentanone oxime. The catalyst is a fluorine-modified Ti-MOR molecular sieve, obtained by reacting the Ti-MOR molecular sieve with an NH4F-alcohol solution. The method provided by this invention features high yield, high purity, and low waste, with a single-pass yield ≥96% and purity ≥99.0%. The catalyst can be recycled up to 6 times without significant activity decline. The entire process involves no organic solvent discharge and low salt content in the wastewater, meeting the requirements of green production.

The application discloses a kind of metal organic framework UiO-66 modified terahertz super surface detection lung cancer marker 2-pentanone method.The method is based on a kind of terahertz multi-resonance super surface sensor, and its unit structure is composed of two S-shaped open resonant ring and an antenna, produces three independent resonant valleys.To improve detection selectivity and structural stability, the application is functionalized to super surface using three-layer modification strategy: APTES is introduced in sequence to form stable interface layer, spin-coated amino-rich PEI layer is provided with additional adsorption sites to interact with ketone molecules, and finally spin-coated metal organic framework UiO-66 is used as sensing layer to realize effective pre-enrichment of 2-pentanone.During detection, three resonant valleys show linear red shift with the increase of 2-pentanone concentration, and the lowest test concentration is 20 ppm.The application uses multi-resonance characteristics combined with multi-dimensional response mode to realize rapid, high-sensitivity and high-selectivity non-contact detection of lung cancer marker 2-pentanone.

This invention relates to the field of chemical synthesis technology, specifically a method for preparing 2,3,3,5-tetramethylindole. The method comprises using p-methylphenylhydrazine hydrochloride and 3-pentanone as raw materials, generating 2,3,3,5-tetramethylindole through a one-step condensation-cyclization reaction in acetic acid medium, followed by further processing steps. This synthetic method offers significant advantages: First, it is highly efficient, with a one-step condensation-cyclization reaction, a molar yield of 60-68%, HPLC endpoint control, and a total processing time of one day, making it suitable for industrial production. Second, it operates under mild conditions, using acetic acid as both solvent and catalyst, with a reaction temperature of 112℃, allowing the use of ordinary enamel-lined reactors and avoiding corrosion from traditional strong acid equipment. Third, it achieves excellent purity, with no isomers and a purity exceeding 99%, offering flexible purification at low cost. Fourth, it is more environmentally friendly, with a dichloromethane recovery rate ≥90%, and wastewater with a near-neutral pH for easy treatment. Fifth, it is easily scaled up, with quantitative formulas for parameters and flexible process adjustments, adaptable to various production fields.

This invention discloses a method for producing 4-hydroxy-2-pentanone from acetone and acetaldehyde, belonging to the field of fine chemical intermediate synthesis technology. The method uses bio-based acetone and bio-based acetaldehyde as raw materials, and 1,8-diazabicyclo[5.4.0]undec-7-ene as a catalyst. In a DBU-H₂O catalytic system, high-purity 4-hydroxy-2-pentanone is obtained through a cross-aldol condensation reaction followed by separation and purification. This invention solves the technical problems of low product yield, numerous by-products, dark product color, strong odor, and difficulty in catalyst recovery in existing technologies by optimizing reaction parameters and selecting specific catalysts. The reaction conditions are mild, the operation is simple, and the energy consumption is low. The catalyst can be recycled, and all raw materials are bio-based, meeting the requirements of green chemical development. It is suitable for large-scale industrial production, and the product can be widely used in bakelite preparation, flavorings, pharmaceutical intermediates, and other fields.

The invention belongs to the technical field of fermentation engineering, and particularly relates to Wickerhamomyces anomalus JG-WA1 and application thereof in aroma-enhancing fruit wine. A strain of aroma-enhanced Wickerhamomyces anomalus JG-WA1 is screened from distiller's yeast, apple juice is inoculated with the strain for primary fermentation, then saccharomyces cerevisiae is inoculated for secondary fermentation, and the aroma-enhanced fruit wine is prepared. The content of unpleasant odor substances such as acetone, 4-methyl-1-pentanol, 2-butanol, dimethyl disulfide, 3-hexanone and the like with pungent smell of alcohol or mildew odor and the like in the fruit wine is obviously reduced, while the content of 2-pentanol, ethyl propionate, propyl acetate, 3-methyl-2-pentanone, 3-pentene-2-ketone, hexyl hexanoate, ethyl hexanoate, methyl acetate, heptanal, 2-octanone, 2, 3-pentanone, ethyl hexanoate, ethyl hexanoate, methyl acetate, heptanal, ethyl hexanoate, ethyl hexanoate, ethyl hexanoate, ethyl hexanoate, ethyl hexanoate, ethyl hexanoate, ethyl hexanoate, ethyl hexanoate, ethyl hexanoate, ethyl hexanoate and ethyl hexanoate is obviously reduced. The content of fruit flavor components such as 2, 3-dimethylpyrazine is greatly increased, the brewed apple wine is obvious in ester flavor and transparent and bright in color, and the flavor quality is obviously improved.

This invention discloses a method for preparing 1,2-pentanediol, comprising using 2-pentanone as a substrate, adding 2-keto reductase, linalool dehydratase, formate dehydrogenase, lysozyme, coenzyme NAD+, and water to react and obtain n-pentene. The obtained n-pentene is then thoroughly mixed with ethanol. This mixture is then fed into a reaction system containing olefin monooxygenase, epoxide hydrolase, formate dehydrogenase, lysozyme, coenzyme NAD+, MgSO4, and water using a fed-batch method. After the n-pentene and ethanol mixture has been completely added, the reaction continues for a period of time, followed by extraction to obtain 1,2-pentanediol. This preparation method uses 2-pentanone as a raw material, catalyzing the synthesis of 2-pentanol via 2-keto reductase. 2-pentanol is then catalyzed by a dehydrating enzyme to generate n-pentene, which is then catalyzed by an olefin monooxygenase to generate 1,2-epoxypentane. Finally, epoxide hydrolase ring-opens the 1,2-pentanediol. This process requires only four enzymatic catalytic reactions for efficient synthesis.

[Problem] To provide a pattern collapse inhibiting composition and a method for producing a pattern using the pattern collapse inhibiting composition. [Solution] A pattern collapse inhibiting composition comprising a solidifying component (A) and a solvent (B), wherein the solidifying component (A) is dicyclopropylketone oxime, 2,2,4,4-tetramethyl-3-pentanone oxime, or a mixture thereof. The pattern collapse inhibiting composition is a highly functional material that can be used in a semiconductor device production process of a nanotechnology process, for example, a semiconductor device production process for controlling a liquid crystal, quantum dot, or OLED display formed on a substrate.

The invention discloses durian essence and a preparation method thereof, and the durian essence is prepared from the following raw materials: 2.0 to 3.8 percent of methyl 2-methylbutyrate, 1.6 to 3.4 percent of ethyl 2-methylbutyrate, 0.8 to 1.6 percent of 3-mercaptohexyl acetate, 0.4 to 1.2 percent of dipropyl disulfide, 0.01 to 0.1 percent of 4-mercapto-4-methyl-2-pentanone, 0.8 to 2.0 percent of citral, 1.5 to 3.0 percent of hops tincture, 1.0 to 2.2 percent of 2, 6-dimethyl-5-heptenal and 80.0 to 88.0 percent of solvent. According to the durian essence, a certain amount of acetic acid 3-mercaptohexyl ester and citral are added into common durian essence components such as methyl 2-methylbutyrate and dipropyl disulfide, and on the basis that the storage stability of the durian essence is guaranteed, the pure and full aroma profile of durian can be highly restored.

The invention discloses a preparation method of non-grain bio-based pentamethylene diamine, and relates to the technical field of bio-based chemical preparation. The preparation method of the non-grain bio-based pentamethylene diamine comprises the following steps: adding furfural and a first catalyst into a first solvent, introducing hydrogen, carrying out a furfural hydrogenation reaction, and recovering the first catalyst to obtain a reaction liquid of cyclopentanone; adding ammonia water and a second catalyst into the reaction liquid of cyclopentanone, introducing oxygen, carrying out ammoxidation reaction on cyclopentanone, and recovering the second catalyst to obtain a reaction liquid of glutaronitrile; and adding the reaction liquid of the glutaraldehyde and a third catalyst into a second solvent, adding alkali liquor to adjust the pH value to 8-12, introducing hydrogen, carrying out a glutaraldehyde hydrogenation reaction, recovering the third catalyst, and carrying out rectification and purification to obtain the pentamethylene diamine. The preparation method disclosed by the invention does not depend on grain raw materials, the process is green and environment-friendly, the catalyst is stable in circulation, and industrial large-scale production and high-purity application scenarios can be met.

The utility model relates to the field of separation and purification, and provides a separation device of an azeotropic mixture and a production system of 4-methyl-2-pentanone. The utility model provides a separation device for an azeotropic mixture. The separation device comprises a first rectifying tower, a phase splitting device, a dehydrogenation reaction tower, a second rectifying tower and a third rectifying tower, a top discharge port of the first rectifying tower is communicated with a feed port of the phase splitting device, a middle discharge port of the first rectifying tower is communicated with a feed port of the dehydrogenation reaction tower, and a bottom discharge port of the first rectifying tower is communicated with a feed port of the second rectifying tower; a bottom discharging hole of the phase splitting device is communicated with a feeding hole of the second rectifying tower; a bottom discharge hole of the second rectifying tower is connected with a first ketone extraction pipe; and a bottom discharge port of the dehydrogenation reaction tower is communicated with a feed port of the third rectifying tower. The device can be used for effectively realizing the separation of a mixture of water, 4-methyl-2-pentanone, 4-methyl-2-pentanol, C9 and heavy components.

The invention discloses a reaction device for continuously preparing perfluoro-2-methyl-3-pentanone. The reaction device comprises a raw material storage unit, a premixing unit, a reaction unit, a conveying unit and a separation and circulation unit. The premixing unit is used for mixing a first raw material (triethylamine) and a second raw material (acetonitrile) to form homogeneous organic liquid; the reaction unit utilizes a micro-mixer and a delay coil pipe to enable the organic liquid and a third raw material (perfluoro-2-methyl-2, 3-epoxypentane) to be subjected to shear mixing and continuous reaction; the separation circulating unit is used for separating a product through a liquid separator and refluxing an organic phase to the pre-mixing unit for recycling. A liquid-liquid reaction mode is adopted, the blocking risk of a solid catalyst is eliminated, the reaction efficiency and the raw material conversion rate (up to 99.9%) are remarkably improved, continuous production is realized, and the material loss and the production cost are reduced.

A process for producing a C10-C18 dialkylcycloalkane, the process comprising: (i) subjecting a furfural compound, a furfuryl alcohol compound or a mixture of a furfural compound and a furfuryl alcohol compound to a reductive rearrangement reaction in the presence of water, hydrogen and a hydrogenation catalyst comprising a supported transition metal, to produce a reaction product comprising an active methylene group-containing cyclic ketone selected from the group consisting of cyclopentanone, substituted cyclopentanone, cyclohexanone or substituted cyclohexanone and mixtures thereof; (ii) reacting the active methylene group-containing cyclic ketone obtained in step (i) with a furfural compound in an aldol condensation reaction in the presence of a catalyst to produce a reaction product comprising an unsaturated C10-C18 oxygen-containing cyclic organic dimer and / or trimer compound; (iii) subjecting the unsaturated C10-C18 oxygen-containing cyclic organic dimer and / or trimer compound produced in step (ii) to a hydrogenation reaction in the presence of hydrogen and a hydrogenation catalyst to produce a saturated C10-C18 oxygen-containing cyclic organic dimer and / or trimer compound; and (iv) subjecting the saturated C10-C18 oxygen-containing cyclic organic dimer and / or trimer compound produced in step (iii) to a hydrodeoxygenation step in the presence of hydrogen and a hydrodeoxygenation catalyst to produce a hydrocarbon product comprising C10-C18 dialkyl cycloalkanes, wherein the reaction product of step (i) is subjected to an azeotropic distillation step (ia) to produce a distillate stream comprising a majority of the active methylene group-containing cyclic ketone and a bottoms stream comprising a majority of water and a fraction of the active methylene group-containing cyclic ketone, the cyclic ketone containing active methylene groups is recovered from the reaction product produced in step (i), wherein the distillate stream is used as a feed in step (ii).

The invention discloses a depolymerization method of a 3-chloro-5-hydroxy-2-pentanone dimer and a 3-chloro-5-hydroxy-2-pentanone solution, and relates to the field of organic synthesis. The depolymerization method comprises the following steps: mixing a 3-chloro-5-hydroxy-2-pentanone dimer with a polar solvent to obtain a first solution; mixing the first solution with a basic catalyst and an aromatic carboxylic acid compound containing hydroxyl to obtain a second solution; carrying out a depolymerization reaction on the second solution at a first temperature to obtain a third solution; and adjusting the pH value of the third solution to obtain the 3-chloro-5-hydroxy-2-pentanone solution. The depolymerization method of the 3-chloro-5-hydroxy-2-pentanone dimer, disclosed by the invention, has the characteristics of high depolymerization rate, high selectivity and high product purity, and is beneficial to full utilization of chemical resources.

This invention discloses a method for synthesizing 2-pentylcyclopentenone and the catalyst used. The method uses 2-pentylcyclopentenone and hydrogen as raw materials, and performs a hydroisomerization reaction in the presence of a catalyst to obtain 2-pentylcyclopentenone. The catalyst is a supported catalyst and includes a support, an active metal, a rare earth metal oxide, and a modifier. The active metal and rare earth metal oxide are supported on the support. The support includes zinc aluminate with a spinel structure. The modifier contains phosphorus and / or nitrogen. This synthesis method achieves high conversion of 2-pentylcyclopentenone, high selectivity and high purity of the target product 2-pentylcyclopentenone, and the process is relatively simple, suitable for industrial production. The catalyst exhibits high catalytic activity and high stability.

The application provides a method for determining ultra-low content thallium in iron ore, which adopts an extraction separation method to extract thallium from a multi-component test solution containing iron, calcium, aluminum and silicon, realizes separation and enrichment, and then determines by using an inductively coupled plasma emission spectrometer; the application utilizes the chemical properties of thallium and alkane compounds containing active oxygen substituents represented by 4-methyl-2-pentanone, adopts an extraction method for separation and enrichment, establishes a suitable analysis method, and completes the detection of ultra-low content thallium in ore.

The application relates to the technical field of synthesis of organic silicon materials, and particularly discloses a safe and efficient pentanone oxime silane and a preparation method thereof. The preparation method of the safe and efficient pentanone oxime silane comprises the following steps: dissolving 2-pentanone oxime in a first organic solvent to obtain a first solution; dissolving vinyl trihalosilane in a second organic solvent to obtain a second solution; under the conditions of stirring and 20-35 DEG C, the second solution is added dropwise into the first solution, after the dropwise addition is completed, the reaction is continuously carried out until completion, and a reaction liquid is obtained; the reaction liquid is cooled to room temperature, filtration is carried out, the filtrate is collected, and concentration drying is carried out, so that 2-pentanone oxime silane is obtained. The application can improve the boiling point of 2-pentanone oxime silane, the viscosity of the 2-pentanone oxime silane is moderate, the 2-pentanone oxime silane has good processing performance, and the application range is wide.

The invention discloses a synthesis method of meso-position diarylamino substituted heptamethine, and belongs to the technical field of organic synthesis. Cyclopentanone is used as a raw material, and the meso-position diarylamino substituted heptamethine cyanine dye is obtained after two condensation, boronation and coupling steps. The synthesis route avoids the imine intermediate in the traditional route, thereby avoiding the generation of high-toxicity and high-corrosivity hydrogen fluoride gas and being more beneficial to industrialization. The whole synthetic route is subjected to four-step reaction, the reaction condition is mild, the operation is easy, and the total yield of cyclopentanone exceeds 30%.

The invention belongs to the technical field of medical examination, and particularly relates to application of detection reagents of eight metabolic markers in preparation of breast cancer diagnosis and prognosis products. The metabolic markers are heptanal, 2-pentanone, 2, 2-dimethyl-propionic acid, 2-decyl decahydronaphthalene, 3, 4, 5, 6, 7, 8-hexahydro-2 (1H)-naphthalenone, 2-[(2-cyano-3, 3-dimethyl cyclopropyl) methyl]-2-methyl-1, 3-dioxolame, methyl isopropyl disulfide and dimethyl silane glycol, and the PubChem CID is 8130, 7895, 6417, 586218, 572673, 560018, 123494 and 11137539 in sequence; research results show that compared with normal healthy people, the combined diagnosis index of the eight metabolic markers in the urine of the breast cancer patient is increased, the eight metabolic markers can be used as the urine marker for predicting the incidence of the breast cancer, the combined evaluation curative effect index of the eight metabolic markers is increased after treatment, and the breast cancer treatment effect can be evaluated. The result provides a specific, rapid and noninvasive detection means for early diagnosis, dynamic monitoring and prognosis of breast cancer, and has wide clinical application value.

The invention discloses a preparation method of 2-bromo-2-cyclopentenone, which comprises the following steps: taking cyclopentanone (compound III) as a starting raw material, firstly carrying out bromination reaction to obtain 2, 2-dibromocyclopentanone (compound II), and finally carrying out elimination reaction to obtain the product 2-bromo-2-cyclopentenone (compound I), the total yield can reach 82.59%, the raw materials in the route are low in cost and easy to obtain, and the method is suitable for industrial production. The use of dangerous reagents is avoided, the post-treatment is mild and efficient, and the method has great large-scale production potential and economic value.

The present invention provides a method for synthesizing 5-hydroxy-4,6-dimethylbenzocyclopentanone, which relates to the field of organic chemical synthesis technology and includes a two-step reaction. Specifically, using 2-methoxy-1,3-dimethylbenzene as a starting material, it first reacts with 3-chloropropionyl chloride to obtain 4-methoxy-3,5-dimethyl-1-(3-chloropropionyl)benzene. Then, the 4-methoxy-3,5-dimethyl-1-(3-chloropropionyl)benzene undergoes intramolecular cyclization and demethylation to obtain 5-hydroxy-4,6-dimethylbenzocyclopentanone. The synthetic route of the present invention is short and feasible, the starting materials and excipients are inexpensive and readily available, the reaction is highly reactive, the operation is simple and easy to control, and the yield of the target product is high.