WO2012114144A1 - Method for obtaining fluorene by crystallization from the melt - Google Patents
Method for obtaining fluorene by crystallization from the melt Download PDFInfo
- Publication number
- WO2012114144A1 WO2012114144A1 PCT/IB2011/000699 IB2011000699W WO2012114144A1 WO 2012114144 A1 WO2012114144 A1 WO 2012114144A1 IB 2011000699 W IB2011000699 W IB 2011000699W WO 2012114144 A1 WO2012114144 A1 WO 2012114144A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- fluorene
- oil
- crystallization
- melt
- during
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/14—Purification; Separation; Use of additives by crystallisation; Purification or separation of the crystals
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Water Supply & Treatment (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to a method for obtaining purified fluorene of purity higher than about 97 w/w % from fluorene fraction oil, wherein the fluorene fraction oil, recovered from the distillation of coal tar feedstock oil containing fluorene and dibenzofuran, is treated then by crystallization from the melt, said crystallization being carried out with the liquid fluorene fraction oil which is slowly cooled down during a cooling step to a temperature between about 95 to 115°C, said temperature depending of the starting fluorene content in said fluorene fraction oil.
Description
METHOD FOR OBTAINING FLUORENE BY CRYSTALLIZATION FROM THE MELT
TECHNICAL FIELD:
The invention relates to a method for obtaining fluorene by crystallization from the melt proceeding from a fluorene fraction oil containing dibenzofuran, recovered from the distillation of a coal tar feedstock oil containing fluorene.
STATE OF THE ART:
Fluorene is an intermediate product for the production of dyes, pigments, pesticides, polymers and pharmaceuticals. A most significant application for fluorene is the production of fluorenone used to produce FMOC chloride or of fluorene-9-carboxylic acid used as an intermediate in the synthesis of drugs.
Fluorene can be produced in a synthetic way by chemical reaction starting from benzene as a raw material. Benzene is reacted with chloride in presence of aluminium chloride and forms a chlorobenzene intermediate. The chlorobenzene intermediate is then reacted with copper to form biphenyl. The latter is then reacted with methylene chloride to form fluorene and hydrochloric acid.
An alternative to this step synthesis is the recovery of fluorene from coal tar feedstock. In average, fluorene represents around 1.7-2.2 % w/w in coal tar. The recovery of fluorene from coal tar feedstock is a way of choice for large scale industrial production.
However, the purification grades required for the purified fluorene are typically above 95 w/w % and preferably 97 w/w % or most desirably 99 w/w %.
A classical process for the industrial production of fluorene from coal tar feedstock is depicted by a combination of fractional distillation of a fluorene oil fraction followed by a re-crystallization in presence of a solvent.
Typical fluorene fraction oil boils between 280 and 305°C and is recovered from a fore-running anthracene oil production. The fluorene is obtained by recrystallization of a fluorene distillate obtained from rectification of the fluorene oil fraction with water, solvent naphtha, isopropanol or methanol as typical solvents.
The fluorene fraction oil contains fluorene (boiling point: 295°C) but also other main compounds, namely acenaphthene (boiling point: 279°C), dibenzofuran (boiling point: 285°C) and phenanthrene (boiling point: 340°C).
Considering the temperature differences the acenaphthene and the phenanthrene can be efficiently removed by distillation process but significant amounts of dibenzofuran will remain mixed with fluorene in the fluorene fraction oil because of the very close values of the boiling points temperatures. If an increased of the distillation separation efficiency between dibenzofuran and fluorene is theoretically possible, it leads in practice to the design of columns that are industrially unrealistic for continuous operation. In order to cope with this limitation, a batch distillation process or a combination of continuous rectification followed by batch distillation for efficient separation of fluorene and dibenzofuran has therefore to be foreseen; it however leads to serious degradation of process efficiency mainly in terms of recovery yield of fluorene and does not suffice to achieve the purity required for purified fluorene.
A second purification with a different technique is therefore required: the crystallization. However, even under optimum distillation conditions for the dibenzofuran/fluorene separation, the amount of dibenzofuran in the
fluorene fraction oil shall be strictly controlled and limited to maximum acceptable values to allow conditions that will authorize purification by common crystallization techniques. Indeed, the study of mixtures of fluorene with dibenzofuran shows that these two compounds form a series of solid solutions which is considered to hinder the performance of further separation of fluorene and dibenzofuran by a crystallization process. So, for example the dibenzofuran content shall be below 3 w/w % in the fluorene fraction oil in order to allow reaching pure fluorene by recrystallization with methanol. In addition to dibenzofuran some traces of phenanthrene and carbazole also remain in the fluorene fraction oil and will contribute in various extend to the decrease of the performance of a recrystallization process. The reason is that the fluorene crystalline system forms eutectic mixtures with phenanthrene and multiples other compounds originally present in the coal tar feedstock and remaining as traces in the fluorene distillate.
Because of these different reasons, the fluorene/dibenzofuran system seems not to be easily purified by crystallization techniques alone and serious composition constraints should be applied to the fluorene fraction oil obtained by distillation. The minimum fluorene content required may vary from 60 to 96.5 w/w % or more and preferably from 95 to 96.5 w/w %. The fluorene over dibenzofuran mass ratio allowed may be up to 0.05 and preferably lower than 0.03 and most desirably lower than 0.02.
For fluorene fraction oil within the afore-mentioned specifications recrystallization processes in presence of a solvent can be used. The fluorene crystals are then separated from the solvent by centrifugal treatment and dried in order to remove the remaining solvent. According to the solvent used, some impurities that usually form eutectic mixture or co- crystallize with fluorene can also be washed away in various extends. The recovered solvent shall also be regenerated for example by distillation. However, such a combination of recrystallization and centrifugation leads
to increased operating costs and, according to the type of solvent used, to additional losses of fluorene. This recrystallization can be operated in batch, fed batch or under continuous method.
As an alternative to simple re-crystallization and if the purity that would be achieved by re-crystallization in presence of a solvent only is not high enough, the fluorene can be subject to caustic washing in presence of a water immiscible solvent contacted with an aqueous solution of soda so that hydrogen atom in position 9 of the fluorene molecule is removed. Under such conditions the fluorene is dissolved in the aqueous phase whereas other impurities remain in the organic phase. Then the fluorene is neutralized with an acid such as benzoic acid and re-crystallized. It is then dried by any appropriate method. As previously the process requires having re-treatment of the solvent and of the aqueous streams. It also adds a consumption of soda and acid.
Consequently, by any of the methods or combination of the methods described above the fluorene cannot be produced under a continuous process combining distillation and crystallization from the melt. Indeed, the conditions of the distillation shall be properly selected and controlled which drives to a batch process.
The technical problem of the present invention is to find the means of continuously purifying fluorene fraction in presence of dibenzofuran proceeding from coal tar feedstock oil containing fluorene in order to produce purified fluorene, advantageously with more than 97% w/w of purity grade in liquid form. The invention aims also to maximize recovery yields for fluorene, advantageously with a recovery yield higher than 70%. The present process can be used to manufacture reduced quantities as well as large ones with moreover an excellent reproducibility and no additional consumptions of chemicals or solvents.
DISCLOSURE OF THE INVENTION:
The object of the invention is a method for obtaining purified fluorene from coal tar feedstock oil containing fluorene by melt crystallization. Said coal tar feedstock oil containing fluorene is supplied by a coal tar distillation. After distillation of said coal tar feedstock oil containing fluorene, a fluorene fraction oil is obtained which undergoes a melt crystallization: the fluorene fraction oil also called "melt" is subject to a combination of slow cooling and heating cycles up to provide purified fluorene.
The starting material for the method according to the present invention is a coal tar feedstock oil containing fluorene.
The coal tar oil containing fluorene is obtained by distillation of wash oil, acenaphthene oil or anthracene oil resulting during coal tar distillation or a mixture of oils thereof in variable parts.
The present invention relates to a method for obtaining purified fluorene of purity higher than about 97 w/w % from fluorene fraction oil, wherein the fluorene fraction oil, recovered from the distillation of coal tar feedstock oil containing fluorene and dibenzofuran, is treated then by crystallization from the melt, said crystallization being carried out with the liquid fluorene fraction oil which is slowly cooled down during a cooling step to a temperature between about 95 to 115°C, said temperature depending of the starting fluorene content in said fluorene fraction oil.
The content of fluorene in said fluorene fraction oil resulting from the distillation of a coal tar oil containing fluorene can vary from 50 to 96.5 w/w %, preferably above 55 w/w % or most preferably above 60 w/w %.
The cooling rate during the cooling step of the crystallization can be lower than about 0.05 "C.min"1, preferably lower than about 0.01°C.min" 1 and more preferably lower than about 0.005°C.min"1.
Said crystallization from the melt can be a static melt crystallization.
A non-solidified residual oil formed during the cooling step can be drained in a draining step, the drain oil appearing during said draining step being drained off, and allowing to appear fluorene crystals formed during said crystallization, afterwards said fluorene crystals are slowly heated during a sweating step, the sweating oil appearing during the sweating step being drained off, forming thus, after being melted and collected, a purified oil of fluorene, the heating rate applied during said sweating step being lower than about 0.05°C/min"1 and preferably below about 0.01°C/min"1 and more preferably below about 0.005°C/min"1.
The heating rate applied during the sweating step can be below about 0.005°C/min"1, when the purity of the fluorene fraction oil is higher than about 94 w/w %.
Said drain oil can be subjected to a purification by crystallization as defined above, said crystallization being able to be repeated more than once.
The oil streams can be (i) collected after purification of said drain oil by crystallization, (ii) concentrated and then (iii) recycled into the upstream distillation of coal tar feedstock.
The crystallization operation can be repeated until the required final purity of fluorene is achieved.
The content of fluorene in the fluorene fraction oil resulting from the distillation of a coal tar oil containing fluorene may vary from 50 to 96.5 w/w % or more and preferably above 55 w/w % or most desirably above 60 w/w %.
The content of phenanthrene in the fluorene fraction oil resulting from the distillation coal tar oil containing fluorene may vary from 1 to 50 w/w % or more and preferably below 30 w/w % or most desirably below 10 w/w %.
The content of dibenzofuran in the fluorene fraction oil resulting from the distillation coal tar oil containing fluorene may vary from 1 to 40 w/w % or more and preferably below 20 w/w % or most desirably below 5 w/w %.
The production of fluorene fraction oil by distillation can be operated by any kind of distillation considered as being suitable to the purpose by the man of the art.
In a preferred embodiment, a vacuum distillation process will be retained in order to avoid overheating of the sump of the distillation apparatus. Such a overheating would induce temperature conditions favourable to the formation of sludge and polymers or gums from the compounds in the coal tar feedstock oil containing fluorene. This would contribute to lower the recovery yield in fluorene as some of it may be involved in the formation of the gums.
The fluorene fraction oil which has a crystallization temperature higher than 115°C and which is recovered from the distillation of the coal tar feedstock oil containing fluorene among other things is then treated by crystallization from the melt. The crystallization is carried out with the liquid fluorene fraction oil also called "melt" in the present text. The fluorene fraction oil is usually in a liquid form at a temperature between 95 and 118°C.
During a cooling step, said melt is slowly cooled down to a temperature between about 95 and about 115°C, said temperature depending of the starting fluorene content included in said melt and permitting the initiation of the crystals formation. The cooling is done in a dedicated melt crystallization vessel. In a preferred embodiment, the melt crystallization vessel is a melt static crystallizer.
An accurate control of the temperature of the melt under crystallization is required and shall insure a homogeneous control of the temperature in the entire melt.
For fluorene fraction oil with fluorene content below about 60 w/w %, or above about 95 w/w % the temperature shall be controlled with less than about 0.2°C of temperature difference between the colder and the hotter volume element of the melt.
For fluorene content with fluorene content below about 70 w/w % but above about 60 w/w%, or above about 90 w/w% but below about 95 w/w %, the temperature shall be controlled with less than about 0.3°C.
The efficiency of the purification of fluorene by crystallization from the melt appears to be possible only under such highly controlled temperature conditions during crystallization.
Additionally, an accurate control of the cooling rate applied during the cooling step shall be followed in respect of the kinetics of growth of the fluorene crystals. The cooling rate during the cooling step of the crystallization shall be lower than about 0.05 °C.min"1 and preferably lower than about 0.01°C.min"1 or most preferably lower than about 0.005°C.min"1.
After cooling, the non-solidified residual oil also called "drain oil" and which contains less fluorene and more impurities than the fluorene fraction oil, can be removed or drained from the melt crystallization vessel, and fluorene crystals can be isolated then. The efficiency of the draining of the non-solidified residual oil is intimately linked to the cooling rate applied during crystallization.
At the same time, the drain oil is collected and may be subjected to a comparable purification by crystallization from the melt. This allows an increased recovery of the fluorene contained in the oil streams collected under the form of oils with a concentrated content in fluorene higher than in the drained oils initially crystallized. The concentrated oil is then recycled upstream in the coal tar feedstock oil containing fluorene fed into the upstream distillation. Under most usual crystallization from the melt
processes such oil would have been recycled in an upstream stage of crystallization from the melt which would have exhibited a comparable content in compound to be recovered. In the case of fluorene purification from coal tar feedstock oil containing fluorene such a strategy shall be avoided as it would lead to an concentration loop of compounds that cannot be removed by crystallization such as traces anthracene. Such a concentration loop would hinder the efficiency of the crystallization in the long term.
After the draining, a thin layer can form at the surface of the crystals previously formed. Indeed, the crystals can be covered with a filming layer of liquid having the same composition than the non-solidified residual oil. This non-solidified residual oil can exhibit fluorene content lower than the fluorene content of the initial fluorene fraction oil fed into the crystallization from the melt vessel and an increased content in dibenzofuran and other impurities.
Said fluorene crystals can be subsequently slowly heated during a sweating step to promote enhanced draining of the non-solidified residual oil that could remain at the surface of the crystals. Thus, sweating oil is obtained. This step is referred to as sweating. According to the cooling rate applied during the crystallization, the sweating step is eventually repeated once or more at different increasing temperature levels. The efficiency of the sweating steps requires a very accurate control of the heating rate: the heating rate applied during sweating step shall be lower than about 0.05°C/min"1 and preferably below about 0.01°C/min"1. For fluorene crystals of purity higher than about 94 w/w % the heating rate applied during sweating step shall be below about 0.005°C/min 1.
The sweating oil obtained in that way may be recycled upstream in the feed of the melt crystallization providing its composition in fluorene is comparable to the composition of the fluorene fraction and that no other compound is exhibiting a higher composition than that corresponding in the fluorene fraction.
After the possible drain and sweating oils have been drained off, the crystals can be melted, and purified fluorene can be collected as a liquid. Then, the composition of said oil collected shows an increased content in fluorene and a lower content in dibenzofuran.
According to the required final purity of fluorene, the crystallization operation can be repeated until the final purity is achieved.
The following example will explain the invention in more details without being limited thereto.
EXAMPLE:
A coal tar feedstock oil containing fluorene with a 242-345 °C boiling point range and containing 65 w/w % fluorene, 18 w/w % dibenzofuran and 14 w/w % phenanthrene is distilled under vacuum set at -85 kPa(g). A fluorene fraction oil containing 95 w/w % fluorene minimum, 2 w/w % dibenzofuran and 2 w/w % of phenanthrene is recovered from distillation. Said fluorene fraction is loaded in a melt static crystallizer and cooled down to 1 3.5°C +/- 0.1°C.
After crystallization at 113.5°C has been completed, the melt static crystallizer is drained. The draining is operated at 113.5°C and the drain oil collected shows content in fluorene of about 91.9 w/w %. The remaining mass loaded into the crystallizer is gently heated up from 114.2 to 114.3°C at 0.002°C.min"1 during 30 minutes and then at 0.005°C.min"1 during 8 minutes. The sweating oil collected shows content in fluorene of about 95
w/w % and in dibenzofuran of about 2 w/w %. The mass remaining in the melt static crystallizer is melted and collected as a liquid. It shows a fluorene content of 97.4 w/w %.
The draining oil collected containing about 91.9 w/w % of fluorene is loaded in a melt static crystallizer and cooled down to 112°C +/- 0.1 °C. After crystallization at 112°C has been completed, the melt static crystallizer is drained. The draining is operated at 112°C and the drain oil collected shows content in fluorene of about 88 w/w %. The remaining mass loaded into the crystallizer is then melted. The melted oil collected shows content in fluorene of about 94 w/w % and of 1 w/w % in anthracene.
References list
US patent documents
2.590.096 March 1952 J. Feldman et al.
3.031.463 April ! 962 D.C. Overholt et al.
Others:
H.-G. Franck, "Presently little-used but potentially important coal tar chemicals", National meeting of American Chemical Society, 13 Jan. 1963, Vol 7:1 Conference 143.
Claims
1. Method for obtaining purified fluorene of purity higher than about 97 w/w % from fluorene fraction oil, wherein the fluorene fraction oil, recovered from the distillation of coal tar feedstock oil containing fluorene and dibenzofuran, is treated then by crystallization from the melt, said crystallization being carried out with the liquid fluorene fraction oil which is slowly cooled down during a cooling step to a temperature between about 95 to 115°C, said temperature depending of the starting fluorene content in said fluorene fraction oil.
2. Method according to claim 1 , wherein the content of fluorene in said fluorene fraction oil resulting from the distillation of a coal tar oil containing fluorene varies from 50 to 96.5 w/w %, preferably above 55 w/w % or most preferably above 60 w/w %.
3. Method according to claim 1 or 2, wherein the cooling rate during the cooling step of the crystallization is lower than about 0.05 "C.min"1, preferably lower than about 0.01°C.min"1 and more preferably lower than about 0.005°C.min"1.
4. Method according to anyone of claims 1 to 3, wherein said crystallization from the melt is a static melt crystallization.
5. Method according to anyone of claims 1 to 4, wherein a non- solidified residual oil formed during the cooling step is drained in a draining step, the drain oil appearing during said draining step being drained off, and allowing to appear fluorene crystals formed during said crystallization, afterwards said fluorene crystals are slowly heated during a sweating step, the sweating oil appearing during the sweating step being drained off, forming thus, after being melted and collected, a purified oil of fluorene, the heating rate applied during said sweating step being lower than about 0.05°C/min"1 and preferably below about 0.01°C/min"1 and more preferably below about 0.005°C/min"1.
6. Method according to claim 5, wherein the heating rate applied during the sweating step is below about 0.005°C/min"1, when the purity of the fluorene fraction oil is higher than about 94 w/w %.
7. Method according to claim 5, wherein said drain oil is subjected to a purification by crystallization as defined in anyone of claims 1 to 5, said crystallization being able to be repeated more than once.
8. Method according to claim 7, wherein oil streams are (i) collected after purification of said drain oil by crystallization, (ii) concentrated and then (iii) recycled into the upstream distillation of coal tar feedstock.
9. Method according to anyone of claims 1 to 8, wherein the crystallization operation is repeated until the required final purity of fluorene is achieved.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/IB2011/000699 WO2012114144A1 (en) | 2011-02-25 | 2011-02-25 | Method for obtaining fluorene by crystallization from the melt |
| CN201180068232.5A CN103732565B (en) | 2011-02-25 | 2011-02-25 | For being obtained the method for fluorenes by crystallization from melt |
| RU2013143308/04A RU2558369C2 (en) | 2011-02-25 | 2011-02-25 | Method of obtaining fluorene by crystallisation from melt |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/IB2011/000699 WO2012114144A1 (en) | 2011-02-25 | 2011-02-25 | Method for obtaining fluorene by crystallization from the melt |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2012114144A1 true WO2012114144A1 (en) | 2012-08-30 |
Family
ID=44545775
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/IB2011/000699 WO2012114144A1 (en) | 2011-02-25 | 2011-02-25 | Method for obtaining fluorene by crystallization from the melt |
Country Status (3)
| Country | Link |
|---|---|
| CN (1) | CN103732565B (en) |
| RU (1) | RU2558369C2 (en) |
| WO (1) | WO2012114144A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103382148A (en) * | 2013-07-25 | 2013-11-06 | 攀钢集团攀枝花钢钒有限公司 | Industrial fluorene production process |
| CN109704910A (en) * | 2017-10-25 | 2019-05-03 | 中国石油化工股份有限公司 | The separation method of mixture containing anthracene alkylation reaction product |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3031463A (en) * | 1958-09-10 | 1962-04-24 | Union Carbide Corp | Recovery of fluorene, dibenzofuran and acenaphthene from coal hydrogenation neutral middle oil |
| JPH01216945A (en) * | 1988-02-24 | 1989-08-30 | Nkk Corp | Production of fluorene |
| JPH072705A (en) * | 1991-08-13 | 1995-01-06 | Ado Kemuko Kk | Purification of fluorene |
| WO1998029364A1 (en) * | 1995-06-07 | 1998-07-09 | The Dow Chemical Company | Process for dehydrocyclization |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU1532554A1 (en) * | 1988-04-25 | 1989-12-30 | Украинский научно-исследовательский углехимический институт | Method of extracting fluorene |
-
2011
- 2011-02-25 RU RU2013143308/04A patent/RU2558369C2/en active
- 2011-02-25 WO PCT/IB2011/000699 patent/WO2012114144A1/en active Application Filing
- 2011-02-25 CN CN201180068232.5A patent/CN103732565B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3031463A (en) * | 1958-09-10 | 1962-04-24 | Union Carbide Corp | Recovery of fluorene, dibenzofuran and acenaphthene from coal hydrogenation neutral middle oil |
| JPH01216945A (en) * | 1988-02-24 | 1989-08-30 | Nkk Corp | Production of fluorene |
| JPH072705A (en) * | 1991-08-13 | 1995-01-06 | Ado Kemuko Kk | Purification of fluorene |
| WO1998029364A1 (en) * | 1995-06-07 | 1998-07-09 | The Dow Chemical Company | Process for dehydrocyclization |
Non-Patent Citations (3)
| Title |
|---|
| DATABASE EPODOC EUROPEAN PATENT OFFICE, THE HAGUE, NL; 30 August 1989 (1989-08-30), NIPPON KOKAN KK, MIYAZAWA MAKOTO ET AL.: "Production of fluorene", XP002665826 * |
| DATABASE WPI Week 198941, Derwent World Patents Index; AN 1989-295747, XP002665827 * |
| H.-G. FRANCK: "Presently little-used but potentially important coal tar chemicals", NATIONAL MEETING OF AMERICAN CHEMICAL SOCIETY, vol. 7, 13 January 1963 (1963-01-13), pages 1 |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103382148A (en) * | 2013-07-25 | 2013-11-06 | 攀钢集团攀枝花钢钒有限公司 | Industrial fluorene production process |
| CN109704910A (en) * | 2017-10-25 | 2019-05-03 | 中国石油化工股份有限公司 | The separation method of mixture containing anthracene alkylation reaction product |
| CN109704910B (en) * | 2017-10-25 | 2021-08-06 | 中国石油化工股份有限公司 | Process for separating mixtures containing anthracene alkylation products |
Also Published As
| Publication number | Publication date |
|---|---|
| CN103732565A (en) | 2014-04-16 |
| RU2558369C2 (en) | 2015-08-10 |
| CN103732565B (en) | 2015-11-25 |
| RU2013143308A (en) | 2015-04-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4354046A (en) | Process for obtaining high purity bisphenol A | |
| JP4182273B2 (en) | Method for producing ε-caprolactam | |
| JP2004525893A (en) | Isolation of anthracene and carbazole by melt crystallization | |
| EP2970048A1 (en) | Process for recovering paraxylene from at least two feedstreams containing xylene isomers | |
| KR101849376B1 (en) | Recovery and refining of dianhydrosugars | |
| WO2012114144A1 (en) | Method for obtaining fluorene by crystallization from the melt | |
| US7605296B2 (en) | Method for separating and purifying 2,6-dimethylnaphthalene | |
| TWI430984B (en) | Method for manufacturing adamantane | |
| KR101351326B1 (en) | Method for Preparing Naphthalene | |
| KR100473001B1 (en) | Method for manufacturing 2,6-dimethylnaphthalene | |
| AU2014101600A4 (en) | Method for separating and purifying p-dichlorobenzene | |
| KR100717386B1 (en) | Separation of naphthalene from naphthalene oil and coal tar distillates | |
| CN109574928A (en) | A method of purification cyclohexanone oxime vapour phase rearrangement product | |
| US2506289A (en) | Process for the sepoaration of isomers | |
| JP3584435B2 (en) | Method for producing high-purity indene | |
| CN105601462B (en) | A kind of high pure benzene method of purification | |
| JP2013151487A (en) | METHOD FOR PRODUCING ε-CAPROLACTAM | |
| JPS62138443A (en) | Production of biscresol | |
| US5382725A (en) | Process for the purification of 1,3-dihalobenzene from an isomeric mixture of dihalobenzenes | |
| US5399783A (en) | Preparation of 6,6'-dihydroxy-3,3,3',3'-tetramethyl-1,1'-spirobiindane | |
| KR20020024334A (en) | Method for producing 2,6-dimethylnaphthalene | |
| JPH07179419A (en) | Production of high purity caprolactam | |
| JPS5852235A (en) | Purification of 2,6-dimethylphenol | |
| KR100316555B1 (en) | A method of separating diemethylethylbenzene from naphtha resolution heavy oil. | |
| JPH09176055A (en) | Purification of crystalline substance |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 11724018 Country of ref document: EP Kind code of ref document: A1 |
|
| NENP | Non-entry into the national phase |
Ref country code: DE |
|
| ENP | Entry into the national phase |
Ref document number: 2013143308 Country of ref document: RU Kind code of ref document: A |
|
| 122 | Ep: pct application non-entry in european phase |
Ref document number: 11724018 Country of ref document: EP Kind code of ref document: A1 |