Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/582—Recycling of unreacted starting or intermediate materials

Definitions

• the present invention is directed primarily to a process for preparing polyol esters in the presence of an excess mixture of acids and, optionally, a catalyst. It is also useful for preparing plasticizer esters for polyvinylchloride (PVC) such as phthalates, adipates and trimellitates in the presence of a titanium, zirconium or tin-based catalyst or acid catalyst.
• PVC polyvinylchloride
• the addition of reactants to the esterification reactor are staged so that in the case of polyol esterification either all or a portion of the lower boiling point acid is added to the reaction vessel together with the polyol, followed by the subsequent addition of the higher boiling point acid.
• the lower boiling point acid is at least partially consumed prior to the addition of the higher boiling point acid.
• plasticizer esters when plasticizer esters are formed it is desirable to stage the addition of the higher boiling point alcohol.
• Synthetic esters are used in a variety of applications such as aviation turbine oil basestocks, low-smoke plasticizers, and refrigerant basestocks.
• the reaction conditions under which esterification is effected can be varied considerably. The reaction proceeds very slowly at room temperature, but quite rapidly at elevated temperatures. About 99% of the limiting reagent or reactant, e.g., acids, anhydrides or polyols, is converted to an ester within a few hours. Limiting reagents are typically reagents which are not present in stoichiometric excess, e.g., limiting reagents used to make plasticizers include diacids and phthalic anhydride and those used to make polyol esters are polyols (i.e., polyhydroxy1 compounds) .
• water is a by-product of the reaction. Since the reaction is an equilibrium reaction, it is forced to completion by the removal of the water by-product, typically through distillation of the water from the reaction mixture during the esterification process. Frequently, an entrainer is used to aid in the distillation of the water from the reaction mixture. Inert materials such as benzene, toluene, or xylene may be used as the entrainer. In addition, the reactant having the lower boiling point has also been employed as the entrainer. In this latter case, the reactant used as the entrainer is charged into the reaction mixture in excess over the stoichiometric quantities required for the reaction.
• the conventional procedure is to charge all of the reactants into the reactor at the beginning of the reaction cycle.
• the reaction mixture is then heated and reaction begins.
• the temperature of the reaction mixture rises until the boiling point of the reaction mixture is achieved, at which point the hydrocarbon and water by-product boil out of the reaction mixture.
• the overhead vapors are condensed, the water separated from the hydrocarbon, and the hydrocarbon recycled to the reactor vessel.
• the reaction temperature, and therefore the rate of reaction are thus determined by the boiling point of the reaction mixture.
• the reaction temperature may increase as the reaction proceeds.
• the present invention is not only economically desirable, but it also substantially increases the overall rate at which the reactants are converted to esters. In general, for a given conversion the lower the water content, the faster the rate of reaction.
• the present invention provides a novel method for increasing the rate of the esterification reaction, wherein at least a portion of the lower boiling point components of the mixed lower boiling point reactant (i.e., mixed acids in the case of polyol esters and mixed alcohols in the case of plasticizer esters) is added to the reactor at the outset, followed by the staged or subsequent addition of the higher boiling point components and any remaining lower boiling point components at or following the point when either the reaction mixture reaches its boiling point and/or the lower boiling point component are at least partially consumed by the reaction.
• the mixed lower boiling point reactant i.e., mixed acids in the case of polyol esters and mixed alcohols in the case of plasticizer esters
• the concentration of the mixed lower boiling point reactant in the reaction mixture is less in the present invention than in the conventional esterification process wherein all of the mixed lower boiling point reactant is add yed to the reaction mixture at the outset, the temperature of the reaction mixture will be higher over time than the temperature in the conventional case. Consequently, the reaction temperature, and therefore the rate of reaction, will be higher during staged addition of the mixed lower boiling point reactants than during conventional processing. The higher rate of reaction translates into a shorter reaction time for the staged addition process than for the conventional batch process.
• the concentration of the staged component i.e., typically the higher boiling point component, although in some instances the staged component may include any remaining lower boiling point component which was not added at the start of the esterification reaction
• additional amounts of this component are added to the reaction mixture either in bulk or in stages to ensure that it is present in sufficient quantities to satisfy the reaction requirements.
• the same total amount of the mixed lower boiling point reactant will have been consumed in the staged addition process as in the conventional process wherein all of the reactants are charged to the reactor at the outset.
• the lower boiling point acid or alcohol component of this mixture can present special processing issues during the esterification reaction.
• the water formed during the reaction is very soluble in the C 5 acid relative to the higher molecular S ⁇ weight acid.
• the acid refluxed to the reactor has a high water content which can limit the ultimate conversion without the use of equipment that adds to total investment and unit complexity.
• the C 5 acid has a solubility in the water which can add to waste water handling costs.
• the lower boiling point reactant comprises a mixture of acid or alcohol components which are charged to the esterification reaction vessel such that the higher boiling point acid or alcohol component is added after the reaction mixture begins to reflux or reaches the boiling point of the reaction mixture such that the lower boiling point component is at least partially consumed.
• the present invention involves the reaction of the lower boiling point acid or alcohol component at the outset of the esterification reaction at which point the concentration of hydroxyl groups is higher and therefore the driving force and reaction rates are larger as demonstrated by the below equation:
• the reaction rate equals k multiplied by the concentration of ROH multiplied by the concentration of RCOOH, wherein k is a function of temperature and catalyst concentration.
• the environmental benefits as a result of using less of the lower boiling point component are: (1) less lower boiling point component needs to be stripped from the final product; and (2) less lower boiling point component is present in the water of reaction which ultimately goes to waste water treatment.
• the reaction rate benefits as a result of using less of the lower boiling point component are: (1) the overall time averaged vapor pressure of the esterification mixture is lower and this allows faster heat-up times for a given heat load capability; and (2) less water in the reflux or reaction mixture, especially in the later stages of reaction, minimizes equilibrium constraints. That is, the smaller amount of lower boiling point component present in the acid or alcohol being returned or refluxed to the reaction vessel, the lower the water concentration will be. This will result in a lower water concentration in the reaction mixture at the later stages of the reaction.
• the present invention als ro provides many additional advantages which shall become apparent as described below.
• a process for the esterification of a polyol with mixed acids comprise at least one lower boiling point acid component and at least one higher boiling point acid component.
• the polyol and at least a portion of the lower boiling point acid component are initially added to a reaction vessel to form a reaction mixture and then heated to a temperature at about or above the boiling point of the reaction mixture while maintaining a pressure sufficient to obtain boiling of the reaction mixture, thereby converting the polyol and the lower boiling point acid component to an ester.
• the higher boiling point acid component is added, preferably in stages. Thereafter, water and mixed acids (i.e., substantially larger amounts of the higher boiling point acid component) are removed from the reaction vessel.
• the concentration of the mixed acids in the reaction mixture is monitored and additional higher boiling point acid component is added to the reaction mixture to maintain a certain predetermined concentration of mixed acids.
• the lower boiling point acid component is added at the outset in an amount less than the total amount needed for the overall reaction, then the remaining portion thereof is preferably added after the reaction mixture has reached its boilin fg point. It is desirable that the concentration of the lower boiling point acid component in the reaction mixture be higher than the final concentration consumed.
• the higher boiling point acid component can be added to the reaction mixture at the outset, i.e., prior to heating the reaction mixture to its boiling point.
• the monitoring is preferably conducted by predicting the hydroxyl number via gas chromatography, measuring the water concentration of the reaction mixture, computer modeling of the reaction rate, or any other means capable of monitoring the concentration of the mixed lower boiling point reactant (i.e., the mixed acids) within the reaction mixture.
• the process further comprises the addition of a catalyst to the reaction vessel such that the polyol and mixed acids are catalytically converted to the ester.
• the mixed acid and water by-product is removed from the reaction vessel via distillation.
• the distilled acids and water are thereafter separated such that the acids can be recycled back to the reaction vessel.
• the acids refluxed to the reactor will have a lower solubility of water.
• Staged esterification is also applicable to the formation of plasticizer esters wherein an acid and at least a portion of the lower boiling point alcohol component are initially added to a reaction vessel, followed by the subsequent bulk or staged addition of a higher boiling point alcohol component and any residual lower boiling point alcohol component.
• Monitoring of plasticizer esterification is preferably conducted by titrating the reaction mixture to determine its acidity, measuring the water concentration of the reaction mixture, computer modeling of the reaction rate, or any other means capable of monitoring the concentration of the mixed lower boiling point reactant (i.e., the mixed alcohols) within the reaction mixture.
• the mixed lower boiling point reactant i.e., the mixed alcohols
• This process is also useful in forming plasticizer esters from an anhydride and mixed alcohols, wherein the anhydride and at least a portion of the lower boiling point alcohol component are added to the reaction vessel to form the reaction mixture.
• the higher boiling point alcohol component and any residual lower boiling point alcohol component are then added to the reaction mixture either in bulk or stages.
• Fig. 1 is a graph plotting temperature verses time for various staged and non-staged additions of mixed acids in a polyol esterification process
• Fig. 2 is a pressure profile graph plotting pressure verses time for various staged and non-staged additions of mixed acids in a polyol esterification process. // DESCRIPTION OF THE PREFERRED EMBODIMENTS
• the addition of the reactants to an esterification reaction are staged to allow the lower boiling point component of the mixed lower boiling point reactant to at least be partially consumed prior to the addition of at least a portion of the higher boiling point component of the mixed lower boiling point reactant. This ultimately reduces the presence of the lower boiling point component in the recycle or reflux. Water tends to be more soluble in lower boiling point alcohols and acids. As a result less water is returned to the reaction as reflux acid, especially in the later stages of the reaction when low levels of water are required to achieve high levels of conversion.
• the staged addition of the higher boiling point component of the mixed lower boiling point reactant i.e., either mixed alcohols or acids
• the higher boiling point component of the mixed lower boiling point reactant will be useful in forming all esters (e.g., adipates, trimellitates, phthalates, polyol esters, and complex acid/alcohol esters) where one of the components of the mixed lower boiling point reactant is more volatile than the other.
• the mixed lower boiling point reactant in an esterification process is typically the reactant which is added in stoichiometric excess; whereas the higher boiling point reactant is typically the limiting reagent which is not added in excess.
• the preferred process for the esterification of polyols (i.e., higher boiling point reactant) with mixed acids (i.e., lower boiling point reactant), the mixed acids comprising at least one lower boiling point acid component and at least one higher boiling point acid component includes the addition of a polyol and at least a portion (i.e., between about 25 to 100%, more preferably 50 to 100%, and most preferably 75 to 100%) of the lower boiling point acid component of the mixed acids into a reaction vessel to form a reaction mixture. After partial consumption of the lower boiling point acid component, at least a portion of the higher boiling point acid component of the mixed acids is added to the reaction mixture in stages.
• the mixed acids include a C5 acid and a C 7 acid
• at least a portion (most preferably all) of the C5 acid would be added to the reaction together with the polyol, whereas the C 7 acid would be added to the esterification reaction mixture after partial consumption of the lower boiling point acid component, preferably a portion at a time (i.e., in stages).
• any remaining or residual C5 acid would also be added after the reaction mixture reaches its boiling point. It is also possible, that some of C 7 acid could also be added to the reaction mixture at the outset. However, the roost preferred method of forming esters according to the present invention contemplates that all of the C 5 acid be added at the outset and all of the C 7 acid be added in bulk or stages after the reaction mixture has reached its boiling point and at least a portion of the C5 acid has been consumed. This is also true in the formation of plasticizer esters.
• This process can also be used to convert acids and mixed alcohols to plasticizer esters, wherein at least a portion (i.e., between about 25 to 100%, more preferably 50 to 100%, and most preferably 75 to 100%) of the lower boiling point alcohol component is added at the outset and the higher boiling point alcohol component is added in bulk or stages after either partial consumption of the lower boiling point alcohol component or when the reaction mixture reaches the boiling point of the reaction mixture component.
• Plasticizer esters may also be formed in accordance with another embodiment of the present invention, wherein an anhydride is reacted with mixed alcohols.
• the anhydride and at least a portion (i.e., between about 25 to 100%, more preferably 50 to 100%, and most preferably 75 to 100%) of the lower boiling point alcohol component are added to the reaction vessel in stoichiometric equivalents to form an intermediate reaction product. After partial consumption of the lower boiling point alcohol component occurs, the higher boiling point alcohol component is added to the reaction vessel in bulk or stages.
• the plasticizer esterification process may also include one or more of the following steps: removal of excess acid by stripping, e.g. , nitrogen or steam stripping; addition of adsorbents such as alumina, silica gel, activated carbon, clay and/or filter aid to the reaction mixture following esterification before further treatment, but in certain cases adsorbent treatment may occur later in the process following steam stripping and in still other cases the adsorbent step may be eliminated from the process altogether; addition of water and base to simultaneously neutralize the residual organic acids and hydrolyze the catalyst (if present) ; filtration of solids from the ester mixture containing the bulk of the excess acid by steam or nitrogen stripping under vacuum and recycling of the acid to the reaction vessel; and removing solids from the stripped ester in a final filtration.
• adsorbents such as alumina, silica gel, activated carbon, clay and/or filter aid to the reaction mixture following esterification before further treatment, but in certain cases adsorbent treatment may occur later in the
• the staged addition of the higher boiling point acid component of the mixed lower boiling point reactant allows for a more rapid heating of the reaction mixture due to the change in boiling point of the reaction mixture which in turn produces a higher rate of reaction.
• the reason that the higher boiling point acid component of the mixed acids or lower boiling point reactant is added subsequent to at least partial consumption of the lower boiling point component is to ensure that there is sufficient amount of the higher boiling point acid component contained within the reaction vessel at any one time to guarantee sufficient driving force to achieve the desired high esterification conversion and to maintain an acid concentration necessary for catalyzing the self- catalyzed esterification.
• the refluxed hydrocarbon and water is then separated such that the distilled reactant can be recycled back to the reaction mixture.
• the pressure of the reaction vessel should also be maintained at a level sufficient to reflux the lower boiling point reactant (entrainer) and the water while forming an ester from the reactants.
• ESTERIFICATION CATALYST The esterification process may be conducted in the presence of a catalyst.
• Typical esterification catalysts are titanium, zirconium and tin catalysts such as titanium, zirconium and tin alcoholates, carboxylates and chelates. See U.S. Patent No. 3,056,818 (Werber) which issued on October 2, 1962, and which is incorporated herein by reference.
• Typical titanium alcoholates which can be used as catalysts include tetramethyl titanates, tetraethyl titanates, tetrapropyl titanates, tetra-isopropyl titanates, tetrabutyl titanates, tetrapentyl titanates, tetrahexyl titanates, tetra-octyl titanates, tetranonyl titanates, tetradodecyl titanates, tetrahexadecyl titanates, tetra-octadecyl titanates, tetradecyl titanates, tetraheptyl titanates and tetraphenyl titanates.
• the alkyoxy groups on the titanium atom can all be the same or they can be different.
• the zirconium counterparts of the above alcoholates can be substituted in whole or in part as catalysts.
• the titanium carboxylates which serve as esterification catalysts are polymeric materials having at least one acyl group for each titanium atom.
• Typical titanium acylates which can be employed as catalysts include acylates from 2 to 18 carbon atoms, such as hydroxy titanium acetate, hydroxy1 titanium butyrate, hydroxy titanium pentanoate, hydroxy titanium hexanoate, hydroxy titanium octanoate, hydroxy titanium decanoate, hydroxy titanium dodecanoate, hydroxy titanium tetradecanoate, hydroxy titanium hexadecanoate, hydroxy titanium octadecanoate, hydroxy titanium oleate, hydroxy titanium soya acylate, hydroxy titanium linseed acylate, hydroxy titanium castor acylate, hydroxy titanium tall oil acylate, hydroxy titanium coconut acylate, methoxy titanium acetate, ethoxy titanium butyrate, isopropoxy titanium pentanoate, butoxy titanium hexanoate, isopropoxy titanium octanoate, isopropoxy titanium decanoate, isopropyl titanium dodecan
• Titanium chelates are formed by reacting a titanium compound with a polyfunctional molecule including polyols such as glycols or glycerine and amino alcohols, amino acids, hydroxy acids and polycarboxylic acids.
• Typical chelated esters which serve as catalysts include tetra-ethylene glycol titanate, tetrapropylene glycol titanate, tetrabutylene glycol titanate, tetra-octylene glycol titanate and tetrapolyethylene glycol titanate, dibutoxy di- (ethylene glycol) titanate, di-isopropoxy di-(octylene glycol) titanates, dimethoxy di-(octylene glycol) titanates, diethyoxy di-(octylene glycol) titanates, tetratriethanol amine titanate, tetratriethanol amine- N-oleate titanate, triethanol amine-N-stearate titanate, triethanol amine-N-linseed
• the corresponding zirconium chelates are also useful as catalysts.
• Selected acid catalysts may also be used in this esterification process.
• Some examples of acid catalysts are: sulfuric acid, benzene sulfonic acid, p- toluene sulfonic acid, naphthalene sulfonic acid, aluminum sulfate, aluminum powder, normal decylbenzene sulfonic acid, normal dodecylbenzene sulfonic acid, normal nonylbenzene sulfonic acid, normal octylbenzene sulfonic acid, normal heptylbenzene sulfonic acid, normal hexylbenzene sulfonic acid, normal tridecylbenzene sulfonic acid, normal tetradecylbenzene sulfonic acid, normal dodecane sulfonic acid, normal tridecane sulfonic acid, normal te
• Carboxylic acids which undergo esterification i.e., mono or poly-basic acids, e.g., dibasic or tribasic acids
• Representative acids include acetic, hydroxyacetic, chloroacetic, bromoacetic, cyanoacetic, 5-phenylacetic, triphenyl acetic, propionic, halopropionic, lactic, beta-hydroxy propionic, n- butyric, isobutyric, n-valeric, isovaleric, 5-phenyl-n- valeric, n-heptanoic, caproic, pelargonic, caprylic, lauric, palmitic, lignoceric, alpha-hydroxy lignoceric, malonic, succinic, glutaric, adipic, pimelic, azelaic, sebacic, decane-1,10-dicarboxylic, pentadecane-1,15- dicarboxylic, pentacosane-1,25-dicarboxylic, 1,2,3- propane tricarboxylic, citric, acrylic, alpha-chloro acrylic, beta-chloro acrylic,
• alicyclic acids are cyclopropane carboxylic, cyclobutane carboxylic, cyclopentane carboxylic , cycloheptane carboxylic , cyclohexane carboxylic, 2-hydroxy cyclohexane carboxylic , 1, 1- cyclopropane dicarboxylic , 1 , 2-cyclobutane dicarboxylic, 1 , 3 -cyclobutane dicarboxylic , 1, 4- cyclohexane dicarboxylic , cyclohexane-1 , 2 , 3 , 4 , 5 , 6- hexacarboxylic , cyclopentene-2-carboxylic , 1- cyclohexene-1-carboxylic , hydrocapric , cyclohexadiene- 1,2-dicarboxylic, and 1,3-cyc /lo9hexadiene-l,4- dicarboxylic.
• the aromatic acids include benzoic, o-, - and p- chloro and bromo benzoic, o-, m- and p-hydroxy benzoic, o-, m- and p-nitrobenzoic, o-, m- and p-methoxy benzoic, alpha-napthoic, beta-naphthoic, o-, m- and p- methyl benzoic, o-, m- and p-ethyl benzoic, p-phenyl benzoic, phthalic, isophthalic, terephthalic, hydroxy phthalic, 2,3-dimethyl benzoic, benzene-1,2,4- tricarboxylic, benzene-1,3,5-tricarboxylic, benzene- 1,2, ,5-tetracarboxylic, diacids of naphthalenes and trimellitic.
• neopentanoic acid neoheptanoic, neo-octanoic acid, neononanoic acid, neodecanoic acid, 2-ethyl hexanoic acid, oxo-heptanoic acid (i.e., a mix of isomers derived from oxonation/oxidation of hexenes)
• oxo-decanoic acid i.e., a mix of isomers derived from oxonation/oxidation of mixed nonenes
• oxo-octanoic acid i.e., a mix of isomers derived from oxonation/oxidation of mixed heptenes
• 3,5,5- trimethylhexanoic acid linear C_ ⁇ -C ⁇ g alkanoic acids, and blends thereof.
• the mixed acids comprise a lower boiling point acid component selected from the group consisting of: C4 and C 5 acids, and a higher boiling point acid component selected from the group consisting of: C ⁇ , to Ci ⁇ acids.
• the most preferred lower boiling point acid components are C5 acids (e.g., normal valeric, iso-valeric, and neopentanoic) .
• the lower boiling point acid component is a C ⁇ acid and the higher boiling point acid component is selected from the group consisting of: C7 to Cis acids.
• Anhydrides of mono- and poly-basic acids can be used in place of the acids, especially when plasticizer esters are being formed. These include acetic anhydride, propionic anhydride, n-butyric anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, pimellic anhydride, maleic anhydride, mesaconic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, phthalic anhydride, benzoic anhydride, nadic anhydride, methyl nadic anhydride, hexahydrophthalic anhydride, trimellitic anhydride and mixed anhydrides of monobasic acids. Another anhydride is pyromellitic dianhydride.
• alcohols which can be reacted with acids and anhydrides are, by way of example, most primary and secondary C to C30 monohydric or polyhydric, substituted or unsubstituted alkanols and alkenols, such as, methanol, ethanol, chloroethanol, cyanoethanol, ethoxy-ethanol, phenylethanol, n- propanol, 2-chloropropanol-l, 3-bromo-propanol-l, 2,2- dichloropropanol-1, isopropanol, propanol-2, 2- nitrobutanol-1, 2-nitrobutanol-l, 2-methylpentanol-l, 2-methyl pentanol-3, the primary and secondary octanols, n-dodecanol, 6-dodecanol, lauryl, myristyl, stearyl, 2-propenol-l, 2-butenol-l, 3-pentenol-l,
• Polyols or polyhydric alcohols are represented by the general formula:
• R(OH) n wherein R is an alkyl, alkenyl or aralkyl hydrocarbyl group and n is at least 2, and can be used in place of the mono alcohols when polyol esters are desired.
• the hydrocarbyl group may contain from about 2 to 20 or more carbon atoms, and the hydrocarbyl group may also contain substituents such as chlorine, nitrogen and/or oxygen atoms.
• the polyhydroxy compounds generally will contain from about 2 to 10 hydroxy groups and more preferably from about 2 to 6 hydroxy groups.
• the polyhydroxy compound may contain one or more oxyalkylene groups and, thus, the polyhydroxy compounds include compounds such as polyetherpolyols.
• the number of carbon atoms and number of hydroxy groups contained in the polyhydroxy compound used to form the carboxylic esters may vary over a wide range.
• the following alcohols are particularly useful as polyols: neopentyl glycol, 2,2-dimethylol butane, trimethylol ethane, trimethylol propane, trimethylol butane, mono and technical grade (i.e., 88% mono, 10% di and 1-2% tri) pentaerythritol, dipentaerythritol, tripentaerythritol, ethylene glycol, propylene glycol and polyalkylene glycols (e.g., polyethylene glycols, polypropylene glycols, polybutylene glycols, etc., and blends thereof such as a polymerized mixture of ethylene glycol and propylene glycol) .
• polyalkylene glycols e.g., polyethylene glycols, polypropylene glycols, polybutylene glycols, etc., and blends thereof such as a polymerized mixture of ethylene glycol and propylene glycol
• the method according to the present invention is capable of forming plasticizer esters, such as, phthalates, adipates and trimellitates, from C 4 -C 1 5 alcohols, preferably Cg-C ⁇ oxo-alcohols. Because of the increase in the rate of reaction, in accordance with this invention, the process is particularly useful in esterifications catalyzed by titanium, zirconium, or tin containing catalysts.
• polyol esters such as, neopolyol esters, from polyols and excess fatty acids.
• the polyol or polyol mixture is preferably technical grade pentaerythritol (PE) , trimethyolpropane (TMP) , and neopentylglycol each which can be admixed with monopentaerythritol and/or trimethylol propane or other neopolyols.
• PE pentaerythritol
• TMP trimethyolpropane
• neopentylglycol each which can be admixed with monopentaerythritol and/or trimethylol propane or other neopolyols.
• the preferred acid component is typically a mixture of straight chain acids having five to ten carbon atoms, or a branched chain acid having from five to eighteen carbon atoms, preferably five to nine carbon atoms, namely 2-methylhexanoic, 2- ethylpentanoic, 3,5,5-trimethylhexanoic acids or mixtures thereof.
• the acids are onocarboxylic acids.
• Suitable straight chain acids include, but are not limited to, valeric acid (C 5 ) , enanthic acid (C 7 ) , caprylic acid (Cg) , pelargonic acid (C 9 ) , and capric acid (C ⁇ Q) •
• the branched chain acid may be iso-Cs, iso-C 7 , iso-Cg or iso-Cg.
• the branched chain acid used is the iso-C 7 acid.
• Another preferred branched acid is 3,5,5-trimethylhexanoic acid derived from the oxonation/oxidation of di-isobutylene.
• Still another preferred branched acid is oxo-octanoic acid derived from the oxonation/oxidation of mixed heptenes.
• the mixed alcohols comprise a lower boiling point alcohol component selected from the group consisting of: C 4 to C5 alcohols, and a higher boiling point alcohol component selected from the group consisting of: C ⁇ to Ci alcohols.
• a lower boiling point alcohol component selected from the group consisting of: C 4 to C5 alcohols
• a higher boiling point alcohol component selected from the group consisting of: C ⁇ to Ci alcohols.
• the acid mixture is present in an excess of about 10 to 50 mole percent or more for the amount of polyol used.
• the excess acid is used to force the reaction to completion.
• the composition of the feed acid is adjusted so as to provide the desired composition of product ester.
• the excess acid is removed by stripping and additional finishing.
• Example l Four batch esterification runs were made using valeric acid (C5) , enanthic acid (C7) , and trimethyolpropane (TMP) as the reactants. In run nos. 1 and 3, all the reactants were charged to the reactor at the same time. In run nos. 2 and 4, the valeric acid and TMP were charged to the reactor and heated to allow conversion in progress. Subsequently, the C7 acid was added and the reaction was allowed to continue once the initial batch mixture reached 350°F (177°C) . The addition of C7 was slightly faster in run no. 4 than in run no. 2.
• Table 1 and Figs. 1 and 2 provide a direct comparison between each of the four runs, wherein the staged addition cases exhibit a substantial advantage over the cases where all of the reactants are charged together.
• Run No. 1 Run No. 2 Run No. 3 Run No. 4
• the staged addition of the C 7 acid as exemplified in run nos. 2 and 4 resulted in a faster heat-up of the esterification reaction product than did run nos. 1 and 3 wherein all of the acids were charged at the outset.
• the staged addition runs were at a higher equivalent temperature than the non-staged cases.
• the staged addition cases allowed for more rapid reduction in pressure and achieved a higher conversion (i.e., lower hydroxy1 number) sooner.
• the water content of the reflux in the stages runs will be lower than in the non-staged runs.
• Fig. 2 provides the pressure profiles for the four runs in this example.
• the pressure is in mmHg absolute and all four runs started off at 1 atm pressure. Once a temperature of 428°F (220°C) was achieved, the vacuum was pulled to remove more water. With the higher levels of C5 present, the non-staged runs cannot go to a lower pressure without losing temperature.
• the staged runs were able to go to lower pressures, since there is less free C5 acid present which affects the vapor pressures. That is, 16 the overall time averaged vapor pressure of the reaction mixture from the staged runs is lower and this allowed for faster heat-up times for a given heat load capability.

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• 1995
  • 1995-07-14 WO PCT/US1995/008810 patent/WO1996002489A1/en active Application Filing
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