FR2913683A1 - Crude glycerol-based product useful for producing dichloropropanol which is useful for producing epichlorohydrin and epoxy resins comprises glycerol alkyl ethers in specified amounts - Google Patents

Abstract

Crude glycerol-based product (P1) comprises: glycerol alkyl ethers (0.001-100 g/kg of the product. Independent claims are included for the following: (1) method (M) for purification of the crude glycerol-based product (P1) involving: subjecting the crude product (P1) to at least one treatment optionally under reduced pressure, selected from evaporative concentration, evaporative crystallization, distillation, fractional distillation, stripping or of liquid-liquid extraction; (2) method (M1) for manufacturing dichloropropanol from glycerol involving: method (A): subjecting the crude glycerol-based product (P1) to at least one treatment, optionally under reduced pressure, selected from evaporative concentration, evaporative crystallization, distillation, fractional distillation, stripping or of liquid-liquid extraction; to reduce the content of glycerol alkyl ethers, and obtain a purified product which is then reacted with a chlorinating agent; or method (B): the method (M), and subjecting the purified glycerol obtained, or glycerol to a reaction with a chlorinating agent comprising hydrogen chloride which is obtained at least partially in a process for the manufacture of silica by decomposition of chlorosilane, in a process for the manufacture of hydrogen chloride by direct synthesis starting from chlorine and hydrogen, and/or in a chlorine/fluorine exchange process on organic compounds; (3) method (M2) for manufacturing epichlorohydrin involving: the method (M1), followed by a process for the dehydrochlorination of dichloropropanol; and (4) method (M3) for manufacturing epoxy resins involving: the method (M2), followed by a process in which epichlorohydrin is subjected to a reaction with a compound containing at least two active hydrogen atoms.

Description

Glycerol-based crude product, process for its purification and its

  The present invention relates to a glycerol-based crude product, to a process for its purification and to the use of the purified product in the manufacture of dichloropropanol. Dichloropropanol, for example, is a reaction intermediate in the manufacture of dichloropropanol. the manufacture of epichlorohydrin and epoxy resins (Kirk-Othmer Encyclopedia of Chemical Technology, Fourth Edition, 1992, Vol 2, page 156, John Wiley & Sons, Inc.). According to known processes, dichloropropanol can be obtained in particular by hypochlorination of allyl chloride, by chlorination of allyl alcohol and by hydrochlorination of glycerol. The latter process has the advantage that dichloropropanol can be obtained from fossil raw materials or renewable raw materials, and it is known that petrochemical natural resources, from which fossil fuels are derived, for example petroleum, natural gas or coal, available on the earth are limited.

  It has been found that when the glycerine is contaminated by various compounds such as alkylated glycerol ethers, which may interfere with the separation and treatment operations of the effluents of the processes using glycerin, it can nevertheless be used as raw material in the manufacture of dichloropropanol.

  The invention therefore relates to a glycerol-based crude product comprising alkylated glycerol ethers in an amount of 0.01 to 100 g / kg of crude product. This amount is often at most 90 g / kg, usually at most 50 g / kg, frequently at most 10 g / kg, usually at most 1 g / kg, commonly at most 0, 5 g / kg and frequently at most 0.2 g / kg. This amount is often at least 0.005 g / kg, frequently at least 0.01 g / kg, commonly at least 0.04 g / kg and usually at least 0.1 g / kg. The alkylated glycerol ethers may be mono-, di- and / or triethers of glycerol, the alkyl groups of which are independently selected from among the alkyl radicals, comprising at least 1 carbon atom and at most 8 C atoms.

  These alkyl groups are preferably linear or branched aliphatic alkyl groups, or alicyclic groups and more preferably linear or branched aliphatic groups. The ether function on the alkyl group is via a primary, secondary or tertiary carbon atom. The alkyl groups are preferably selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl groups and more preferably from methyl, ethyl, propyl and butyl groups and particularly preferably from methyl and ethyl. Most preferably, the alkyl group is a methyl group. The propyl group may be chosen from n-propyl and isopropyl groups, and is preferably an isopropyl group. The butyl group may be chosen from 1-butyl, 2-butyl, isobutyl and tert-butyl groups, preferably from isobutyl and tert-butyl groups.

  The alkylated glycerol ethers may be alkylated mono-, di- and tri-ethers of glycerol, preferably mono- and diethers and more preferably monoethers. The methylated, ethylated, propylated, butylated, pentylated, hexylated, heptylated and octylated monoethers of glycerol are preferred. Methylated, ethylated, propylated and butylated monoethers are more preferred. Methylated and ethylated monoethers are even more preferred and methylated monoethers of glycerol are particularly preferred. The propyl ethers may be chosen from n-propyl or isopropyl ethers, and are preferably isopropyl ethers. The butyl ethers may be chosen from 1-butyl, 2-butyl, isobutyl and tert-butyl ethers, and are preferably chosen from isobutyl or tert-butyl ethers. When the alkylated glycerol ethers are di- and tri-ethers, the alkyl groups may be the same or different. These groups are preferably identical.

  The preferred monoethers are 3-alkoxy-1,2-propanediol and 2-alkoxy-1,3-propanediol. The content of 3-alkoxy-1,2-propanediol in the mixture of 3-alkoxy-1,2-propanediol and 2-alkoxy-1,3-propanediol is generally at least 50%, preferably from minus 60% and most preferably at least 70%. This content is at most 95% and preferably at most 90%.

  The methylated monoethers of glycerol are 3-methoxy-1,2-propanediol and 2-methoxy-1,3-propanediol. The content of 3-methoxy-1,2-propanediol in the mixture of 3-methoxy-1,2-propanediol and 2-methoxy-1,3-propanediol is

  3 generally at least 50%, preferably at least 60% and most preferably at least 70%. This content is at most 95% and preferably at most 90%. Ethylated glycerol monoethers are 3-ethoxy-1,2-propanediol and 2-ethoxy-1,3-propanediol. The content of 3-ethoxy-1,2-propanediol in the mixture of 3-ethoxy-1,2-propanediol and 2-ethoxy-1,3-propanediol is generally at least 50%, preferably from minus 60% and most preferably at least 70%. This content is at most 95% and preferably at most 90%.

  Propylated monoethers of glycerol are 3-propoxy-1,2-propanediol and 2-propoxy-1,3-propanediol. The content of 3-propoxy-1,2-propanediol in the mixture of 3-propoxy-1,2-propanediol and 2-propoxy-1,3-propanediol is generally at least 50%, preferably from minus 60% and most preferably at least 70%. This content is at most 95% and preferably at most 90%. The propoxy group may be an n-propoxy or isopropoxy group, preferably an isopropoxy group. Butylated glycerol monoethers are 3-butoxy-1,2-propanediol and 2-butoxy-1,3-propanediol. The content of 3-butoxy-1,2-propanediol in the mixture of 3-butoxy-1,2-propanediol and 2-butoxy-1,3-propanediol is generally at least 50%, preferably from minus 60% and most preferably at least 70%. This content is at most 95% and preferably at most 90%. The butoxy group may be chosen from 1-butoxy, 2-butoxy, isobutoxy and tertbutoxy groups, preferably from isobutoxy and tertbutoxy groups.

  The glycerol-based crude product may also include alcohols. These alcohols are preferably methanol, ethanol, propanol, preferably n-propanol and / or isopropanol, butanol, preferably 1-butanol and / or 2-butanol and / or isobutanol and / or tert-butanol, pentanol, preferably 1-pentanol and / or 2-pentanol and / or 3-methyl-1-butanol, hexanol, heptanol, octanol, ethylene glycol and propylene glycol. When the alkylated glycerol ethers are methyl ethers, the methanol can be present in an amount of 0.1 to 20 g / kg of crude product and ethanol, propanol, butanol, ethylene glycol and propylene glycol. may be present in a total amount of 0.01 to 2 g / kg of crude product. When the alkylated glycerol ethers are ethyl ethers, the ethanol may be present in an amount of 0.1 to 20 g / kg of crude product and methanol, propanol, butanol, ethylene glycol and propylene glycol may be present in a total amount of 0.01 to 2 g / kg of crude product. When the alkylated glycerol ethers are propyl ethers, propanol can be present in an amount of 0.1 to 20 g / kg of crude product and methanol, ethanol, butanol, ethylene glycol and propylene glycol may be present in a total amount of 0.01 to 2 g / kg of crude product. When the alkylated glycerol ethers are butyl ethers, butanol may be present in an amount of 0.1 to 20 g / kg of crude product and methanol, ethanol, propanol, ethylene glycol and propylene glycol may be present in a total amount of 0.01 to 2 g / kg of crude product. The glycerol-based crude product may also comprise water in an amount of at least 0.1 g / kg and at most 100 g / kg. This amount is preferably at most 50 g / kg and more preferably at most 20 g / kg. The glycerol-based crude product may also comprise alkyl esters of fatty acids, glycerol esters such as, for example, mono- and diglycerides, glycerol oligomers and salts. These last impurities can constitute a distinct phase. The term "fatty acid alkyl esters" is intended to denote esters of fatty acids with mono- or polyalcohols with the exception of glycerol, the alkyl group of which is one of the groups previously described for the alkylated ethers of glycerol. These alkyl esters are preferably methyl, ethyl, propyl and butyl esters of fatty acids, more preferably methyl and ethyl esters, and most preferably methyl esters of fatty acids.

  Without wishing to be bound by any theoretical explanation, it is believed that alkylated glycerol ethers and alcohols can come from the glycerin manufacturing process, in particular by transformation of fats or oils, animal or vegetable, by trans-esterification into glycerol. presence of an alcohol, preferably selected from methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, and mixtures of two or more of they, more preferably selected from methanol, ethanol, propanol, butanol, even more preferably from methanol and ethanol. The alcohol is very particularly preferably methanol. Propanol may be chosen from n-propanol, isopropanol and mixtures thereof, and is preferably isopropanol. Butanol may be selected from 1-butanol, 2-butanol, isobutanol, tertbutanol and mixtures of at least two of them, preferably from isobutanol, tert-butanol and mixtures thereof. The invention also relates to a process for purifying the glycerol-based crude product in which the crude product is subjected to at least one treatment, optionally under reduced pressure, of evapoconcentration, of evapocrystallization, of distillation, of fractional distillation, of stripping or liquid-liquid extraction. Evapoconcentration is understood to mean a process of partial evaporation of the crude product making it possible to concentrate the residual product in less volatile species. By evapocrystallization is meant a process leading to crystallize a compound by removing by vaporization a compound promoting its dissolution in the medium. These processes are described by the Perry's Chemical Engineers' Handbook at the 11th section of the 7th edition. By distillation is meant the type of conventional separation in chemical engineering and described for example in the Perry's Chemical Engineers' Handbook at the 13th section of the 7th edition. Fractional distillation is understood to mean a series of distillations in which the distillate is taken off batchwise. Stripping is understood to mean the separation of a substance by the entrainment by means of the vapor of a pure body. In the process according to the invention, this body may be any compound that is inert with respect to glycerol, such as, for example, water vapor, air, nitrogen and carbon dioxide. By liquid liquid extraction is meant bringing into contact with a totally or partially suitable immiscible solvent for selectively extracting the desired compounds optionally in a countercurrent process as described in the Perry's Chemical Engineers' Handbook at the 15th section of the 7th edition. The stripping, evapoconcentration, evapocrystallization, liquid liquid extraction and distillation treatments may be combined, for example in a stripping column surmounted by a distillation section or in a partial evaporator supplying a distillation column or a combination of a liquid extraction, a stripping of the residual solvent contained in the stream enriched in glycerin and a distillation of the solvent enriched in extracted compounds.

  The alkylated ethers of glycerol and the alcohols are recovered in the distilled or stripped fraction, the purified glycerol product is the residue of the distillation or stripping treatment. When the treatment consists of at least partial evaporation of the crude product, the temperature of the glycerine-rich zone is generally at least 0.degree. C., often at least 80.degree. C. and frequently at least 100.degree. The temperature is generally at most 280 ° C, often at most 250 ° C, and frequently at most 200 ° C. The temperature in the glycerin-depleted zones is generally at least -20 ° C, preferably at least 20 ° C. less -10 C, particularly preferably at least C. This temperature is generally at most equal to the temperature of the glycerine-rich zone, preferably at least 5 ° C. at this temperature, particularly preferably less than at least 10 C at this temperature. When the treatment is carried out by liquid-liquid extraction, the temperature is generally greater than or equal to 20 ° C., preferably greater than or equal to 40 ° C., more particularly greater than or equal to 50 ° C. This temperature is generally less than or equal to 200 ° C. C, preferably less than or equal to 150 C and more preferably less than or equal to 120 C. The treatment pressure is generally at least 0.001 mbar. This pressure is generally at most 1 bar, often at most 0.5 bar, frequently at most 0.3 bar and more specifically at most 0.25 bar.

  When the treatment comprises a separate step of evaporation, this is generally carried out at a pressure of less than 2 bar absolute, preferably at a pressure of less than 1 bar absolute, particularly preferably at a pressure of less than 0, 5 absolute bar. It is generally carried out at a pressure of at least 0.1 mbar, preferably at a pressure of at least 0.2 mbar. When the evaporation step is combined with a distillation or fractional distillation step, it is carried out at a pressure at least equal to the pressure of the step carried out at the lower pressure, preferably at a higher pressure of at least 10 mbar at the pressure of the stage carried out at the lowest pressure. The stripping step is generally carried out at a pressure of less than 5 bar, preferably less than or equal to 2 bar. In distillation processes with or without stripping, the reboiling rate is generally at least 1%, often at least 5% and frequently at least 10%. This reflux rate is at most 99% and often at most 50%. By reboiling rate for continuous distillation is meant the flow rate of the fraction vaporized at the boiler by the flow rate of the residue. By reboiling rate, for fractional distillation, in batch means the ratio of the vaporized amount relative to the final residue.

  The proportion of the distilled fraction is generally at most 150 g / kg, often at most 100 g / kg of the glycerol-based crude product. The distillation, fractional distillation or stripping treatment may be preceded or followed by a separation operation of the optional separate phase mentioned above. This separation may for example be decantation, centrifugation, filtration, adsorption or ion exchange. When it is a settling operation can be improved by passing on a coalescer. The adsorption operation is preferably an adsorption operation on activated carbon. After the treatment, a glycerol-based purified product comprising alkylated glycerol ethers in an amount generally less than or equal to 1 g / kg of product is obtained. purified, and methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, ethylene glycol and propylene glycol in a generally lower total amount. at 1 g / kg of purified product. The amount of alkylated glycerol ethers is preferably at most 0.1 g / kg of purified product, more preferably at most 0.01 g / kg and very particularly preferably at most 0.001 g / kg of purified product. g / kg. This amount is usually at least 0.01 mg / kg.

  When the alkylated glycerol ethers are methyl ethers, the amount of methylated glycerol ethers after the treatment is preferably at most 0.1 g / kg of purified product, more preferably at most 0.01 g / kg and very particularly preferably at most 0.001 g / kg. This amount is usually at least 0.01 mg / kg.

  When the alkylated glycerol ethers are ethyl ethers, the amount of ethyl ether of glycerol after the treatment is preferably at most 0.1 g / kg of purified product, more preferably at most 0.01. g / kg and very particularly preferably at most 0.001 g / kg. This amount is usually at least 0.01 mg / kg.

  When the alkylated glycerol ethers are methyl ethers, the total amount of methanol, ethanol, propanol, butanol, ethylene glycol and propylene glycol after the treatment is preferably not more than 0.1 g. kg / kg of purified product, more preferably at most 0.01 g / kg and very particularly preferably at most 0.001 g / kg.

  When the alkylated glycerol ethers are ethyl ethers, the total amount of methanol, ethanol, propanol, butanol, ethylene glycol and propylene glycol after the treatment is preferably not more than 0.1 g. kg / kg of purified product, more preferably at most 0.01 g / kg and very particularly preferably at most 0.001 g / kg. The treatment also reduces the water content and alkyl esters of the glycerol-based crude product.

  Propanol is preferably isopropanol. Butanol is preferably isobutanol or tert-butanol. The invention also relates to a purified glycerol product comprising alkylated glycerol ethers in an amount of from 0.01 mg / kg to 1 g / kg of purified product, preferably from 10 mg / kg to 500 mg / kg of purified product and more preferably from 40 mg / kg to 200 mg / kg of purified product. The invention also relates to a process for producing dichloropropanol from glycerol in which a glycerol-based crude product is subjected to at least one distillation, fractional distillation or stripping treatment in order to reduce the content of the alkylated ethers of glycerol and obtain a purified product which is reacted with a chlorinating agent. The chlorinating agent generally comprises hydrogen chloride. The hydrogen chloride may be hydrogen chloride gas, an aqueous solution of hydrogen chloride or a mixture of both. The chlorinating agent may be derived at least in part from a chlorosilane decomposing silica manufacturing process as described in Ullmann's Encyclopedia of Industrial Chemistry Fifth, Completely Revised Edition, Volume A 23: Refractory Ceramics to Silicon Carbide, 1993, pp. 635-636. In this case, the hydrogen chloride is generally in the form of an aqueous solution of hydrogen chloride.

  The chlorinating agent may be at least partially derived from a process for the manufacture of hydrogen chloride by direct synthesis from chlorine and hydrogen, as described in Ullmann's Encyclopedia of Industrial Chemistry Fifth, Completely Revised Edition, Volume A 13: High-Performance Fibers to Imidazole and Derivatives, 1989, page 289. In this case, hydrogen chloride is generally in the form of a gas or a liquefied gas. In this method of making hydrogen chloride, chlorine and hydrogen can come from any process. The chlorine and the hydrogen are preferably derived at least partially from a method of electrolysis of a brine, more preferably from a brine comprising mainly sodium chloride, potassium chloride or a mixture of the two, and particularly preferably a brine comprising

  9 mainly sodium chloride. The electrolysis process may be a mercury, diaphragm or membrane electrolysis process. The invention also relates to a process for producing dichloropropanol in which glycerol is subjected to a reaction with a chlorinating agent containing hydrogen chloride which has been obtained at least partially in a process for producing silica by decomposing chlorosilane. and / or in a process for producing hydrogen chloride by direct synthesis from chlorine and hydrogen and / or in a chlorine / fluorine exchange process on organic compounds.

  The chlorinating agent may be at least partially derived from a process for producing allyl chloride, and / or a process for producing chloromethanes and / or a process for chlorinolysis and / or a process for producing oxidation of chlorinated compounds at a temperature greater than or equal to 800 C, as described in the application WO2006 / 106153 in the name of SOLVAY SA. The chlorinating agent may be at least partially derived from a process for the manufacture of vinyl chloride and / or 4,4-methylenediphenyl diisocyanate and / or pyrolysis of chlorinated organic compounds and / or metal etching and / or production of dichloropropanol by hypochlorination of allyl chloride and / or be generated in situ in the reaction medium from an inorganic acid and a metal chloride as described in application WO2005 / 054167 in the name of SOLVAY SA. The chlorinating agent may be at least partially derived from a chlorine / fluorine exchange process on organic compounds, such as processes for producing chlorofluorohydrocarbons (HCFCs) and / or hydrofluorocarbons (HFCs). This chlorinating agent may be in gaseous form or in the form of an aqueous solution. A description of methods of making H (C) FCs can be found in Ullmann's Encyclopedia of Industrial Chemistry Fifth, Completely Revised Edition, Volume A 11: Fibers, 5. Synthetic Inorganic, to Formaldehyde, 1988, pages 354. -360. Of these methods, methods of making HFC-134a, HFC-152a, CFC-11, CFC-12, HFC-32, HCFC-142b, HCFC-141b, HFC-143a are preferred. The hydrogen chloride resulting from these processes generally has a hydrogen fluoride content in hydrogen chloride less than or equal to 200 mg / kg, preferably less than or equal to 50 mg / kg, and most preferably lower or equal to 10 mg / kg. Without wishing to be limited by any theoretical explanation, it is believed that a too high content of hydrogen fluoride in the

  Hydrogen chloride used as raw material would lead to rapid corrosion of the materials generally used in devices for producing dichloropropanol from glycerine, such as glazed steel enamel, for example.

  The invention also relates to a chlorinating agent comprising hydrogen chloride and at most 200 mg / kg of hydrogen fluoride per kg of hydrogen chloride. The reaction with the chlorinating agent can be carried out in the presence of a catalyst, preferably a carboxylic acid or a carboxylic acid derivative, and most preferably adipic acid or an acid derivative. adipic. The chlorination reaction is preferably carried out in a liquid reaction medium. The chlorination reaction can be carried out in the presence of a solvent.

  The dichloropropanol formed can be separated from the other constituents of the reaction medium by any separation treatment, for example by distillation, stripping, extraction or adsorption. After this treatment, the other constituents of the reaction medium can be subjected to additional separation treatments such as, for example, filtration in which fatty acid salts can be separated off. When the separation treatment is a distillation, and that is used for the manufacture of dichloropropanol raw product based on glycerol according to the invention, the separated dichloropropanol can be contaminated by different isomers of chloroalkoxypropanol or dialkoxypropanol. The chloroalkoxypropanol or dialkoxypropanol isomers are preferably those for which the alkoxy group is chosen from the methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy and octoxy groups, preferably from the methoxy, ethoxy, propoxy and butoxy groups, more preferably from methoxy and ethoxy groups. The alkoxy group is most preferably the methoxy group. The treatment of the glycerol-based crude product according to the invention has the advantage of reducing the contamination of dichloropropanol by these isomers. The invention finally relates to a process for the manufacture of epichlorohydrin comprising the process for producing dichloropropanol followed by a process for dehydrochlorinating dichloropropanol. When the dichloropropanol is contaminated with different isomers of chloroalkoxypropanol, the epichlorohydrin may be contaminated with -11-alkylglycidyl ethers. The alkylglycidyl ethers are preferably those for which the alkyl group is chosen from the methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl groups, preferably from the methyl, ethyl, propyl and butyl groups, more preferably among the methyl and ethyl groups. The alkoxy group is very particularly preferably the methyl group. This contamination can be reduced by using dichloropropanol made from the purified glycerol product according to the invention. These alkylglycidyl ethers have boiling temperatures very close to that of epichlorohydrin and are therefore very difficult to separate from it. The invention finally relates to a process for the manufacture of epoxy resins comprising the process for producing epichlorohydrin by dehydrochlorinating dichloropropanol. The following examples intend to illustrate the invention without limiting it. Example 1 A crude glycerin from biodiesel production by a methanol transesterification process of rapeseed oil in the presence of a heterogeneous catalyst was distilled under reduced pressure. The operation was carried out in equipment consisting of a flask equipped with a thermocouple sheath, a stir bar for stirring, a thermocouple-sheathed distillation head, a cooled side cooler, 0 C and a flask to collect the evaporate. The compounds not collected in the balloon were condensed in a trap cooled to -78 C. The water and the methanol were first distilled under a reduced pressure of 9 torr at room temperature. The collection of fractions enriched in methyl ether of glycerol was then carried out under a constant pressure of 3 ton with a boiling point of the mixture of 159-160 ° C. and a measured vapor temperature of 151-155 ° C. Three distillate fractions have been collected. The contents of various compounds of the crude glycerin (glycerol-based crude product), collected fractions, the trap and the distillation residue (purified glycerol-based product) are given in Table 1 below. Table 1 product fraction 1 fraction 2 fraction 3 trap crude product purified glycerol base glycerol Quantity (in g) 100.09 4.00 3.78 5.02 1.98 83.26 Constituents (in g / kg ) methanol 2.4 0.006 0.009 0.035 0.008 ethanol 0.014 propanol 0.016 ethylene glycol 0.22 2.2 0.22 0.088 5.4 0.02 propylene glycol 0.14 0.85 0.056 0.024 10 2 isomers of methoxypropanediol 11.3 176 36 11.7 36.7 0.9 glycerol 965 744 957 981 37 992 glycerol monoacetate 0.35 1.4 1.1 0.71 0.12 0.21 3 isomers of diglycerol 2.8 0.01 0.096 1 , 1, 3.4 methyl oleate + methyl linoleate 6.8 78 1.8 0.04 <0.001 glycerol monooleate + glycerol monolinoleate 3.9 1.1 0.92 1.8 2.2 water 6, 8 1.4 0.4 0.5 0.2

  Example 2 A crude glycerin from biodiesel production by a methanol transesterification process of rapeseed oil in the presence of a heterogeneous catalyst was treated with steam under reduced pressure. The operation was carried out in equipment consisting of a balloon equipped with a sheath with thermocouple, a stir bar for stirring, a dip tube for injecting water vapor, a tube thermocouple sheathed head, side cooler cooled to 0 C and a flask to collect the evaporate. Compounds not collected in the flask were condensed in a trap cooled to -78 C. Water vapor at 140 [deg.] C. (33.19 g) was injected over 63 minutes. constant pressure of 26 ton with a boiling point of the mixture of 127-139 C and a measured vapor temperature of 91-97 C. The contents of various compounds of the crude glycerin (glycerol-based crude product) and the residue stripping (purified glycerol product) are shown in Table 2 below. Table 2 crude product produced glycerol-based glycerol-based base Quantity (in g) 148.6 141.64 Constituents (in g / kg) water 6.8 4.9 methanol 2.4 0.017 ethanol 0.014 <0.005 propanol 0.016 <0.005 ethylene glycol 0.22 0.03 propylene glycol 0.14 <0.001 2 isomers of methoxyglycerol 11 3.9 glycerol CP (960-965) CP (994) glycerol monoacetate 0.35 0.37 3 isomers of diglycerol 2 , 8 2.9 methyl oleate + methyl linoleate 6.8 <0.001 Glycerol monooleate + glycerol monolinoleate 3.9 1.7 - main constituent

Claims (13)

  1. Glycerol-based crude product comprising alkylated glycerol ethers in an amount of 0.001 to 100 g / kg of crude product.   2. The crude product according to claim 1 for which the alkylated glycerol ethers are mono-, di- and / or triethers of glycerol whose alkyl groups are independently selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl.   3. The raw product according to claim 2 for which the glycerol ethers are methylated and / or ethylated monoethers of glycerol.   4. Raw product according to any one of claims 1 to 3 for which the alkylated glycerol ethers are methyl ethers and which comprises methanol in an amount of 0.1 to 20 g / kg of crude product and ethanol , propanol, butanol, ethylene glycol and propylene glycol in a total amount of 0.01 to 2 g / kg of crude product when the alkyl group is a methyl radical, or for which the alkylated glycerol ethers are ethers and which comprises ethanol in an amount of 0.1 to 20 g / kg of crude product and methanol, propanol, butanol, ethylene glycol and propylene glycol in a total amount of 0 , 01 to 2 g / kg of crude product when the alkyl group is an ethyl group.   5. Process for purifying the glycerol-based crude product according to any one of Claims 1 to 4, in which the crude product is subjected to at least one treatment, optionally under reduced pressure, of evapoconcentration, of evapocrystallization, distillation, fractional distillation or stripping.   6. Process according to claim 5, in which a glycerol-based purified product comprising alkylated glycerol ethers in an amount of less than 1 g / kg of purified product and methanol, ethanol, propanol, propylene glycol, is obtained. butanol, pentanol, hexanol, heptanol, octanol, ethylene glycol and propylene glycol in a total amount of less than 1 g / kg of purified product.   7. The process as claimed in claim 6, in which a glycerol-based purified product comprising methylated glycerol ethers in a quantity of less than 1 g / kg of purified product and methanol, ethanol, propanol, butanol, ethylene glycol and propylene glycol in a total amount of less than 1 g / kg of purified product, or in which there is obtained a glycerol-based purified product comprising ethyl ethers of glycerol in an amount of less than 1 g. / kg of purified product and methanol, ethanol, propanol, butanol, ethylene glycol and propylene glycol in a total amount of less than 1 g / kg of purified product.   8. Process for the manufacture of dichloropropanol starting from glycerol in which a glycerol-based crude product according to any one of Claims 1 to 4 is subjected to at least one treatment, possibly under reduced pressure, of evapoconcentration. evaprocrystallization, distillation, fractional distillation or stripping so as to reduce the content of alkylated glycerol ethers and to obtain a purified product which is reacted with a chlorinating agent.   9. The process of claim 8 wherein the alkylated ethers are methylated or ethylated ethers, preferably methylated ethers.   A process for producing epichlorohydrin comprising the process of claim 8 or 9 followed by a process for dehydrochlorinating dichloropropanol.   11. A process for the manufacture of dichloropropanol from glycerol according to which a crude glycerol base product according to any one of claims 1 to 4 is subjected to a reaction with a chlorinating agent containing hydrogen chloride which has been obtained at least partially in a process for the manufacture of silica by decomposition of chlorosilane and / or in a process for the manufacture of hydrogen chloride by direct synthesis from chlorine and hydrogen and / or in a chlorine / fluorine on organic compounds.   12. The process according to claim 11 wherein chlorine and hydrogen have been obtained at least partially in a method of electrolysis of a brine.   13. The method of claim 11 or 12 wherein the chlorinating agent comprises hydrogen chloride and at most 200 mg of hydrogen fluoride per kg of hydrogen chloride.