Catalysts esterification

Ester cmde glycerol is usually of high quality however, salt residue from the esterification catalyst is typically present at a concentration of one... 

Two important widely used sulfonic acids are known as TwitcheU s reagents, or as in Russia, the Petrov catalysts. These reagents are based on benzene or naphthalene ( ) and (12), [3055-92-3] and [82415-39-2] respectively. The materials are typically made by the coupling of an unsaturated fatty acid with benzene or naphthalene in the presence of concentrated sulfuric acid (128). These sulfonic acids have been used extensively in the hydrolysis of fats and oils, such as beef tallow (129), coconut oil (130,131), fatty methyl esters (132), and various other fats and oils (133—135). TwitcheU reagents have also found use as acidic esterification catalysts (136) and dispersing agents (137). 

MCCTFascat 4201 Organotin Esterification Catalyst, Technical Data Sheet No. 345, M T Chemicals, Inc., Rahway, N.J., 1978. 

The 1 1 molar addition products of a primary diol and a tetraaLkyl titanate, Ti(OGO)(OR)2 may react with water to give either Ti(OGO)(OH)2 or condensed products (Ti(OGO)O), which can be used as esterification catalysts (64). 

The alkoxy titanate compounds formed by reaction of one mole of tetraalkyl titanate with one mole of a dialkanolamine are excellent esterification catalysts for the manufacture of phthalate-based plasticizers (112). If a 1 1 molar mixture of alkanolamine and water is used ia place of the alkanolamine, oligomeric titanate complexes are formed, which have high catalyst activity and can be used as thixotropic additives to paints and other aqueous coating formulations (113). 

The butyl alcohols undergo esterification with organic acids in the usual manner in the presence of trace amounts of mineral acid catalysts. Esterification is fastest with /-butyl alcohol and slowest with the primary alcohols although /-butyl alcohol undergoes substantial dehydration in the presence of the typical acid esterification catalysts. 

In laboratory preparations, sulfuric acid and hydrochloric acid have classically been used as esterification catalysts. However, formation of alkyl chlorides or dehydration, isomerization, or polymerization side reactions may result. Sulfonic acids, such as benzenesulfonic acid, toluenesulfonic acid, or methanesulfonic acid, are widely used in plant operations because of their less corrosive nature. Phosphoric acid is sometimes employed, but it leads to rather slow reactions. Soluble or supported metal salts minimize side reactions but usually require higher temperatures than strong acids. 

Certain monobutyltin compounds have recently been introduced 561) as esterification catalysts, e.g., in the reaction of phthalic anhydride with octanol to produce dioctyl phthalate. 

M and T Chemicals Inc., Technical Data Sheet "FASCAT 4101 Monobutyltin Esterification Catalyst. Rahway, New Jersey, 1977. 

Tetrabutyl titanates as eco-friendly esterification and trans-esterification catalysts... 

At an industrial scale, the esterification catalyst must fulfill several conditions that may not seem so important at lab-scale. This must be very active and selective as by-products are likely to render the process uneconomical, water-tolerant and stable at relatively high temperatures. In addition, it should be an inexpensive material that is readily available on an industrial scale. In a previous study we investigated metal oxides with strong Bronsted acid sites and high thermal stability. Based on the literature reviews and our previous experimental screening, we focus here on application of metal oxide catalysts based on Zr, Ti, and Sn. 

Several explosions involving methanol and sodium hypochlorite were attributed to formation of methyl hypochlorite, especially in presence of acids or other esterification catalyst. 

Trans-esterification catalysts stable in the presence of water and impurities... 

Di- -octylphthalate is produced commercially as a component of mixed phthalate esters, including straight-chain C6, C8, and CIO phthalates (EPA 1993a). Di- -octylphthalate is produced at atmospheric pressure or in a vacuum by heating an excess of w-octanol with phthalic anhydride in the presence of an esterification catalyst such as sulfuric acid or / -tolucncsul Tonic acid. The process may be either continuous or discontinuous (EPA 1993a HSDB 1995). Di- -octylphthalate can also be produced by the reaction of -octylbromide with phthalic anhydride. 

The esterification of TPA is catalyzed by protons and in standard industrial operations neither an additional esterification catalyst nor a polycondensation catalyst is added to the esterification reactor. Some new antimony-free polycondensation catalysts [125-128] also affect the speed of esterification significantly and it could be advantageous to add them directly into the slurry preparation vessel. Co-monomers, which should be randomly incorporated into the polymer chains, are usually fed into the slurry preparation vessel. How and when additives, catalysts, colorants and co-monomers are added influences the overall reaction rate and therefore affects the product quality. 

The conventional synthesis of aliphatic polyesters based on adipic acid and a range of diols, such as 1,4-butanediol or 1,6-hexanediol, involves a high-temperature esterification reaction typically at 240-260 °C and an organometallic catalyst such as stannous octano-ate. The use of enzyme catalysis results in a much lower reaction temperature, but also the possibility of removing the esterification catalyst, giving the polyester significantly improved hydrolysis resistance. 

Esterification of linalool requires special reaction conditions since it tends to undergo dehydration and cyclization because it is an unsaturated tertiary alcohol. These reactions can be avoided as follows esterification with ketene in the presence of an acidic esterification catalyst below 30 °C results in formation of linalyl acetate without any byproducts [71]. Esterification can be achieved in good yield, with boiling acetic anhydride, whereby the acetic acid is distilled off as it is formed a large excess of acetic anhydride must be maintained by continuous addition of anhydride to the still vessel [34]. Highly pure linalyl acetate can be obtained by transesterification of tert-butyl acetate with linalool in the presence of sodium methylate and by continuous removal of the tert-butanol formed in the process [72]. 

Dehydrolinalool, obtained by ethynylation of 6-methyl-5-hepten-2-one, can be converted into dehydrolinalyl acetate with acetic anhydride in the presence of an acidic esterification catalyst. Partial hydrogenation of the triple bond to linalyl acetate can be carried out with, for example, palladium catalysts deactivated with lead [73]. 

Di(2-ethylhexyl) adipate can be prepared by the reaction of adipic acid and 2-ethylhexanol in the presence of an esterification catalyst such as sulfuric acid or /lara-toluenesulfonic acid (National Library of Medicine, 1999). 

Yamamoto and co-workers reported the use of scandium(lll) triflate as an esterification catalyst when acetic anhydride was used as the acetate source.5 6 While they only reported on monoalcohols (1°, 2°, and 3°) on a small scale, the submitters modified the Yamamoto procedure to suit the submitters reaction with the 1,1,2-triphenyl-1,2-ethanediol. As detailed above, the current procedure provides a yield of the HYTRA acetate that is comparable to the procedure reported by Braun and coworkers,2 1 but via simple, direct filtration for the reaction mixture. 

Thus, the above mentioned additives, as well as the refining of the esters, can be eliminated. The use of auxiliary liquids is also unnecessary. The esterification process patented in the Federal Republic of Germany in 1951 (6) now makes it possible (besides other processes developed on a similar basis (16, 22)) to produce plasticizer esters of excellent quality, simply and cheaply. In this connection we should like to mention the use of titanic acid esters as esterification and trans-esterification catalysts known since 1955 (29), and 1951 (15). 

According to our findings, all soluble metal compounds of an amphoteric nature are effective esterification catalysts. If, when concluding the theoretical considerations, the amphoteric nature of the metals is described as their ability to function as cations in salts, and also to form anionic hydroxy or alkoxy complexes, this offers the possibility of using the reaction mechanism just discussed for all effective metals in a correspondingly modified manner. 

---