Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D317/00—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms
  • C07D317/08—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3
  • C07D317/10—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3 not condensed with other rings
  • C07D317/14—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3 not condensed with other rings with substituted hydrocarbon radicals attached to ring carbon atoms
  • C07D317/18—Radicals substituted by singly bound oxygen or sulfur atoms
  • C07D317/20—Free hydroxyl or mercaptan

Definitions

• the present invention relates to a process for producing dioxolane from crude glycerol obtained from raw materials such as crude glycerol obtained during the manufacture of biodiesel or glycerol obtained during transformation of fats or oils.
• the invention aims in particular to dissolve glycerol in an organic solvent and form an insoluble phase comprising the salts included in the crude glycerol; and then reacting the obtained glycerol with an aldehyde or a ketone.
• Glycerol is also a by-product of biodiesel which is generally obtained by the transesterification of glycerides with short chain alcohols, for example methanol or ethanol.
• the transesterification reaction is catalyzed by an acid or a base, depending on the characteristics of the oils and / or greases used.
• the resulting esters are separated from excess reactants, catalyst and by-products by a two-step process. First, the glycerol is separated by decantation or centrifugation, then the soaps, the catalyst and alcohol residues are removed by washing with water and bubbling or using magnesium silicate with filtration.
• the significant production of biodiesel as an alternative to fossil sources is accompanied by a high production of crude glycerol obtained as a by-product.
• the crude glycerol obtained includes impurities such as glycerides and salts that involve many complex processing steps before it can be used to make dioxolane.
• a purity greater than 95% of glycerol containing very small amounts of residual salts is obtained; and the solvent used can be perfectly recycled.
• the dioxolane obtained has a purity quite equivalent with a dioxolane conventionally manufactured from pure glycerol.
• the present invention thus relates to a process for the manufacture of dioxolane comprising at least the following stages:
• step (d) adding to the liquid phase or glycerol (if step (c)) a catalyst, and optionally a ketone or an aldehyde, to form a dioxolane by catalyzed reaction between glycerol and the ketone or aldehyde; and
• the insoluble phase is generally a heterogeneous dispersed phase in the majority phase and may be related to a precipitate.
• the process of the invention can be carried out continuously or discontinuously.
• the steps mentioned can be performed successively and one after the other or not.
• Each of the steps of the process can be carried out continuously or discontinuously.
• the crude glycerol is preferably obtained from renewable raw materials, in particular the crude glycerol is obtained during the manufacture of biodiesel or obtained during the transformation of fats or oils, particularly animal or vegetable fats or oils.
• the crude glycerol is generally obtained by saponification reaction, transesterification and / or hydrolysis of animal or vegetable fats or oils.
• the crude glycerol generally comprises from 5 to 95% by weight of glycerol, in particular from 40 to 90% by weight of glycerol.
• Crude glycerol also includes inorganic salts, glycerides, water and other organic compounds.
• the crude glycerol may optionally be treated for the process of the invention, in particular for example by adjusting the pH, filtration or distillation. It is thus possible to filter the crude glycerol to remove insoluble organic material and / or distill it generally at temperatures between 100 and 120 ° C at atmospheric pressure to remove water and volatile compounds. Part or all of the water contained in the crude glycerol can also be evaporated before glycerol is dissolved in the solvent.
• Step a) of the process according to the invention aims at dissolving the glycerol in the organic solvent and forming an insoluble phase comprising the salts of the crude glycerol.
• the solvent according to the invention may in particular be a ketone, an alcohol, an aldehyde, an acetal and / or a ketal.
• Acetals are obtained by nucleophilic addition of an alcohol to an aldehyde in an acidic medium, followed by removal of water.
• the ketals are obtained by the same type of reaction performed on ketones.
• the ketones preferentially used are acetone, cyclohexanone, methyl cyclohexanone, cyclopentanone, methyl cyclopentanone and methyl isobutyl ketone (MIBK).
• the preferred aldehydes are formaldehyde, acetaldehyde and furfuraldehyde.
• the alcohols preferentially used are ethanol, methanol and isopropanol.
• the ketals and acetals are preferably dioxonales such as 2,2-dimethyl-1,3-dioxolane 4 methanol (solketal) for example.
• Step a) no catalyst capable of catalyzing a reaction between the glycerol and the organic solvent or solvents of the medium, especially an esterification catalyst, will be used.
• Step a) can last between 2 minutes and 1 hour. It can be carried out at a temperature of between 10 and 100 ° C., in particular between 20 and 50 ° C.
• the pH during this step can be between 6 and 12, preferably between 7 and 12.
• the mass ratio between the crude glycerol and the solvent is in particular a function of the solubility of the glycerol in said solvent, and for example preferably between 1/1 and 1/50.
• Step b) aims at the separation of the precipitate obtained in step a) from the liquid phase comprising the solvent and the dissolved glycerol.
• filtration, decantation or centrifugation can be carried out.
• Step c) is optionally aimed at separating the solvent and glycerol which is dissolved in the solvent.
• evaporation or distillation can be carried out for this purpose.
• step c) it is also possible to separate the water contained in the crude glycerol.
• the evaporation will include the passing of the organic solvent (s) in the gaseous state so as to recover the glycerol in the liquid state.
• one or more distillation columns can be used.
• the different compounds can be distilled on the same distillation column by varying the temperature, and possibly the pressure; for example proceed to the distillation of the organic solvent, then an increase in the temperature to distill the glycerol.
• This step c) may in particular be used to purify the glycerol and to rid the medium of an organic solvent which may be involved in the catalyzed reaction forming dioxolane of step d).
• Step d) is intended to form dioxolane by reacting the glycerol with an aldehyde or a ketone in the presence of a catalyst.
• This reaction can be carried out in the liquid phase comprising glycerol or else with glycerol freed from the organic solvent or solvents if a step c) has been carried out.
• a ketone or an aldehyde may be added, in particular if a step c) has been carried out and as a function of the solvent or solvents used in step a).
• the ketones preferentially used are acetone, cyclohexanone, methyl cyclohexanone, cyclopentanone, methyl cyclopentanone and methyl isobutyl ketone.
• the preferred aldehydes are formaldehyde, acetaldehyde and furfuraldehyde. It is particularly possible to use according to the invention one or more ketones and / or aldehydes to react with glycerol in the reaction medium.
• glycerol and ketone or aldehyde in the reaction medium.
• a molar ratio of 1 to 5 of ketone or aldehyde relative to glycerol may be used.
• glycerol in a loop and add small proportions of ketone or aldehyde; in particular from 5 to 20 mol%.
• the dioxolane formed generally corresponds to the following general formula (I):
• R and R 1 represent, independently of one another, a hydrogen atom or an alkyl chain comprising from 1 to 10 carbon atoms, especially from 1 to 5 carbon atoms, such as in particular methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl and isopentyl.
• R or R 1 In the case of a reaction with an aldehyde, one of the groups R or R 1 is a hydrogen atom. In the case of a reaction with a ketone, the groups R and R 1 do not represent a hydrogen atom.
• the dioxolane formation reaction is generally conducted at a temperature between 0 and 150 ° C, preferably between 20 and 80 ° C.
• This reaction can be carried out for 30 minutes to 8 hours, usually between 1 and 5 hours.
• This reaction is preferably carried out in acidic medium, in particular with a pH ranging from 2.5 to 7.0.
• acid catalysts for this reaction such as organic or inorganic acids or their salts, may be used.
• acid catalysts for this reaction such as organic or inorganic acids or their salts.
• acetic acid, sulfuric acid, methanesulphonic acid, ion exchange resins of carboxylic or sulfonic type may be used.
• a base for example, sodium carbonate or sodium hydroxide may be mentioned.
• Unreacted aldehyde and ketone can be removed by simple distillation. It is possible to separate the dioxolane formed from the reaction medium by distillation, preferably under reduced pressure. To carry out the distillation, one or more distillation columns can be used. In particular, the different compounds can be distilled on the same distillation column by varying the temperature, and possibly the pressure; for example, to distill the ketone or aldehyde, then increase the temperature to distill the water, and then increase the temperature to distill the dioxolane formed.
• the commercially available crude glycerol has the following composition: 79.3% by weight of glycerol, 15.8% by weight of water, 1.61% by weight of Na + and 2.56% by weight of Cl-.
• Example 1 The commercially available crude glycerol has the following composition: 79.3% by weight of glycerol, 15.8% by weight of water, 1.61% by weight of Na + and 2.56% by weight of Cl-.
• the ketal can be further purified by distillation.
• the amount of purified glycerol recovered is 106.7 g.
• the amount of glycerol / 2,2-dimethyl-1,3-dioxolane-4-methanol mixture is 221.25 g.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Heterocyclic Compounds That Contain Two Or More Ring Oxygen Atoms (AREA)

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• 2010
  • 2010-09-15 FR FR1003666A patent/FR2964658B1/fr not_active Expired - Fee Related
• 2011
  • 2011-09-07 WO PCT/EP2011/065438 patent/WO2012034905A1/fr active Application Filing
  • 2011-09-07 US US13/823,754 patent/US20130178638A1/en not_active Abandoned
  • 2011-09-07 CN CN2011800443894A patent/CN103097372A/zh active Pending
  • 2011-09-07 BR BR112013005871A patent/BR112013005871A2/pt not_active IP Right Cessation
  • 2011-09-07 EP EP11754391.8A patent/EP2616452A1/de not_active Withdrawn

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