Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C43/00—Ethers; Compounds having groups, groups or groups
  • C07C43/02—Ethers
  • C07C43/03—Ethers having all ether-oxygen atoms bound to acyclic carbon atoms
  • C07C43/04—Saturated ethers
  • C07C43/13—Saturated ethers containing hydroxy or O-metal groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C41/00—Preparation of ethers; Preparation of compounds having groups, groups or groups
  • C07C41/01—Preparation of ethers
  • C07C41/02—Preparation of ethers from oxiranes
  • C07C41/03—Preparation of ethers from oxiranes by reaction of oxirane rings with hydroxy groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C43/00—Ethers; Compounds having groups, groups or groups
  • C07C43/02—Ethers
  • C07C43/03—Ethers having all ether-oxygen atoms bound to acyclic carbon atoms
  • C07C43/04—Saturated ethers
  • C07C43/10—Saturated ethers of polyhydroxy compounds
  • C07C43/11—Polyethers containing —O—(C—C—O—)n units with ≤ 2 n≤ 10

Definitions

• This invention relates to a process for the synthesis of glycol ethers over intercalated metal oxides or hydroxides.
• Glycol ethers are versatile molecules which combine the best solvency features of alcohols and ethers. Glycol ethers have miscibility and solvency for a wide range of organic chemicals as well as water. For these reasons, glycol ethers figure prominently in the (i) surface coating industry as active solvents for resins, (ii) brake fluid industry as solvents, (iii) petroleum industry as anti-icers in various petroleum based fuels, (iv) automotive industry as anti-freezes and (v) speciality products for use in households. It is well known that such glycol ethers can be produced by the reaction of an alcohol with an olefin oxide in the presence of an acidic or basic catalyst.
• cationic clays comprise negatively charged metal silicate sheets intercalated with hydrated cations, eg the smectite clays.
• a further class of well known clays are the anionic clays which are the intercalated metal oxides or hydroxides, especially layered double hydroxides
• LDHs low density polyethylene glycol dimethacrylate
• anionic clays are different from the conventional cationic clays in that these comprise positively charged double hydroxide sheets intercalated with anions and, as such, form a complementary class of materials to conventional cationic clays.
• Such compounds are described in eg "Anionic Clay Minerals", by Reichle, W T, "Chemtec", January 1986 and have the empirical formula:
• Such compounds consist of positively charged metal oxide or hydroxide sheets with intercalated anions and water molecules.
• the positively charged layers are b ⁇ /cite- ⁇ ke [Mg(OH)2J with trivalent cations substituting for divalent cations in octahedral sites of the hydroxide sheet. Sorption of hydrated anions renders the structure electrically neutral.
• LDHs containing various combinations ofthe divalent cations M 2+ (eg Mg 2+ , Zn 2"1” , Cu 2"1" , Ni 2+ , Fe 2+ , Co 2+ etc) and trivalent cations M*- "1" (eg Al-* *1"1" , Cr- 54" , Fe*- "1” etc) and anions
• M*- "1" eg Al-* *1"1" , Cr- 54" , Fe*- "1” etc
• anions A m " eg halogens, oxoanions, organic anions etc
• a pre-crystallized LDH Clay cf.K J Martin and T J Pinnavaia "J Am Chem Soc", 108, p.
• hydrotalcite MggAl2(OH)i6
• calcined LDHs have catalytic activity.
• US-A-4458026 discloses that catalysts prepared by calcination of hydrotalcite- ⁇ ke compounds may be used to perform aldol condensations.
• JP-A- 54111047 describes the preparation of alkylene glycol ether acetates using calcined LDHs.
• EP-A-339426 discloses the use of calcined hydrotalcite for the ethoxylation and/or propoxylation of compounds containing active hydrogen atoms.
• Naturally-occurring LDH clays contain mainly carbonate anions in their interlamellar domain. Such materials normally have low activity as catalysts for the preparation of glycol ethers; it was believed that calcination enhances their activity.
• Calcination of LDHs can be carried out over a wide range of temperatures, eg from 200-600°C, depending upon their structure and composition, and usually leads to the reversible collapse of their layered structure (Sato et al, Reactivity of Solids, 2, pp 253-260 (1986) and Sato et al, Ind. Eng. Chem., Prod. Res. Dev., 25, pp89-92 (1986)) and results in the formation ofa spinel M 2+ M2 ⁇ + O4, together with free M 2+ O. All the above documents require that the LDHs be used as a catalyst in the calcined form, ie in a form having a collapsed layered structure.
• JP-A-Hl-304043 discloses that hydrotalcite-like compounds carrying copper ions and in which hydroxyl ions are present at anion exchange sites catalyse the vapour-phase hydrolysis of aromatic halides.
• hydrotalcite anionic clays having hydroxides of copper and chromium in their framework structure can be produced, which clays for the purposes ofthe present invention can also be termed as LDH clays, and can also be converted into pillared clays by inco ⁇ oration in their interlamellar space of large anions, especially metal anions and (poly)oxometallate anions.
• hydrotalcite clays which have hydroxides of magnesium, aluminium, copper and/or chromium in their framework and which have metal anions or (poly)oxometallate anions in the interlamellar space thereof, especially in their uncalcined form, are useful catalysts for producing glycol ethers.
• the present invention is a process for making glycol ethers said process comprising reacting an olefin oxide with an alcohol over a catalyst comprising an LDH with its layered structure intact and having interlamellar anions at least some of which are metal anions or (poly)oxometallate anions.
• the olefin oxide used as reactant is suitably ethylene, propylene and/or a butylene oxide.
• the alcohol used for the reaction is suitably an aliphatic, cycloaliphatic or an aromatic alcohol and may be a mono- di- or poly-hydric alcohol. Monohydric alcohols are preferred. Specific examples of alcohols include the C1-C6 alcohols, especially, methanol, ethanol, the isomeric propanols and the isomeric butanols.
• the alcohol is suitably used in a molar excess if the desired end product is a monoglycol ether.
• the molar ratio of alcohol to the olefin oxide is suitably at least 2: 1 and is preferably in the range from 4: 1 to 15: 1, most preferably in the range from 5:1 to 12: 1.
• the interlamellar anions present are inorganic metal anions, oxometallate or polyoxometallate anions and suitably include inter alia one or more of the following anions: chromium, vanadium, molybdenum and phosphorus, and (poly)oxoanions thereof.
• the terms (poly)oxoanions and (poIy)oxometallate anions are meant to include both oxoanions and oxometallate anions and the polyoxo derivatives thereof.
• a copper-chromium hydrotalcite anionic clay when exchanged with (poly)oxometallate anions, results in materials which have considerably improved selectivity as catalysts for the reaction of alcohol with olefin oxides.
• Such an ion- exchange can be carried out by conventional techniques on a precursor such as, eg by starting with a chloride precursor (which is readily synthesised by co-precipitation), a terephthalate precursor or a dodecylsulphate precursor.
• Methods of preparing hydrotalcite anionic clays are well known in the art. One such method is described in US-A-4458026.
• solutions of soluble salts of divalent and trivalent metals are mixed together with a solution of a base such as eg sodium hydroxide and/or sodium carbonate at a controlled pH value or range.
• a base such as eg sodium hydroxide and/or sodium carbonate
• the resulting mixture is vigorously stirred at room temperature until a slurry is formed which is then optionally heated, suitably between 50°C and 200°C for several, until sufficient crystallisation occurs to form an LDH.
• the resulting LDH is then filtered, washed and dried and generally has a chloride or a carbonate as the interlamellar anion.
• Materials containing other ions may be prepared either by ion-exchange or by adapting the synthesis method so that the desired ions are inco ⁇ orated in the interlamellar domain.
• the optimum reaction temperature will depend upon the reactants used but will generally be in the range from ambient to about 250°C suitably from 50°C to 150°C.
• the reaction can be carried out at a pressure in the range from atmospheric to about 50 bar (5000 KPa).
• the process ofthe present invention can be used for instance for the reaction of butan-1-ol with one or more units of ethylene oxide to make butyl-monoglycol ether (BMGE), di-glycol ether(BDGE), tri-glycol ether etc.
• BMGE butyl-monoglycol ether
• BDGE di-glycol ether
• tri-glycol ether tri-glycol ether
• the material prepared in 1(a) (lg) was suspended in an aqueous solution of 0.1 M terephthalic acid (100 ml). The pH was maintained at a value of 7.5 using 2M NaOH solution during 5 hours at room temperature with vigorous stirring.
• the XRD pattern ofthe terephthalate phase thus obtained showed ⁇ (003) spacing of 13.95A which facilitated the insertion ofa voluminous decavanadate anion.
• the terephthalate phase (1 g) was suspended in an aqueous solution of 0.1 M sodium metavanadate (100 ml) maintained by the addition of dilute nitric acid at a pH value of 4.5 during 3 hours at room temperature.
• the subsequent treatments of washing and drying were carried out in a manner identical to those described in 1(d) above.
• the XRD pattern ofthe resulting product which was not well crystallised, showed a ⁇ (003) spacing of 11.61 A.
• the terephthalate phase prepared in 1(e) above (1 g) was suspended in an aqueous solution (0.1M, 100 ml) of Na2MoO4.2H2O.
• the pH ofthe solution was maintained at 4.5 by addition of dilute nitric acid over 3 hours at room temperature in order to keep the heptamolybdate anion, [Mo ⁇ 24] ⁇ ", so formed in solution.
• the subsequent washing and drying treatments were carried out in a manner identical to those described in 1(d) above.
• the XRD pattern ofthe resulting product showed a ⁇ (003 ) spacing of 12.77A.
• the above catalysts were tested for their ability to promote the epoxidation of alcohols in a stainless steel reactor (0.9 cm internal diameter) fitted with a thermowell.
• the catalyst bed volume used was 5 cm*- 5 in each case.
• the reaction was carried out using a mixed liquid feed prepared under pressure consisting of butan-1-ol (6 moles) and ethylene oxide (1 mole).
• the ethylene oxide co-feed was maintained in the liquid phase in the feed pot by having a 10 barg (1000 KPa) nitrogen head pressure.
• the reactor temperature was then slowly (at about 1°C per minute) increased to 120°C over a period of about 2 hours. -When steady state was reached at this temperature and pressure (which corresponded to 0 hours on-stream), aliquots ofthe reaction mixture were sampled and analysed at regular intervals. The samples were analysed using a Pye-Unicam 4500 gas chromatograph fitted with a WCOT fused silica capillary column (50 m, 0.25mm internal diameter, CP-Sil-5) operating with a temperature programme (80°C for 10 minutes, ramping at the rate of 6°C/minute to 250°C) to determine the relative amounts of mono-glycol ether, higher-glycol ethers and by-products formed. Mass balances were typically 98% or higher for any test period. The results ofthe tests are shown in Table 1 below.
• Kyowa KW-2100 LDH was calcined at 450°C for 18 hours under nitrogen atmosphere and cooled in a desiccator under dynamic vacuum. 20 g of calcined material was slurried in degassed distilled water (produced by boiling distilled water and cooling under a nitrogen blanket) for 1 hour to ensure maximum dispersion. The mixture was kept under a nitrogen atmosphere to avoid contamination by atmospheric carbon dioxide. A suspension of 30.5 g of sodium vanadate in 1 litre of degassed water (0.25M) was further degassed with nitrogen at 65°C for 1/2 an hour. Then the pH ofthe solution was increased to 10 by the addition of 2M NaOH when a clear colourless solution was obtained.
• Kyowa -2100 calcined LDH was further calcined at 450°C under a nitrogen flow for 14 hours. 41.9 g of this material was added to 500 ml of distilled water which had been degassed by purging with a stream of nitrogen. The resulting slurry was heated to 80°C, and stirred under a nitrogen atmosphere for 48 hours. Removal ofthe water on a rotary evaporator at 80°C followed by drying at 80°C gave the final product. The X-ray powder diffraction pattern showed a highly crystalline material with a ⁇ (003) spacing of 7.7 A. 1. Production of Glycol Ethers using catalysts h-k above.
• Examples (h) to (j) illustrate that higher BMGE selectivities can be obtained with the pillared LDH clay catalysts than with a commercial potassium acetate catalyst (example m).
• Comparative example (k) using a non-pillared Mg-Al LDH clay shows that BMGE selectivity is reduced if the pillar is omitted.
• the non-pillared catalyst also lost physical integrity and crystallinity (by X-ray diffraction) under reaction conditions. With the pillared materials the catalyst was easily recovered post reaction, and could be re-cycled with no loss in MBGE selectivity (example h(a)).

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• 1995
  • 1995-06-22 GB GBGB9512727.0A patent/GB9512727D0/en active Pending
• 1996
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