2-Ethyl hexanol Production

The aldol reaction is probably one of the most important reactions in organic synthesis. In many industrially important hydroformylation processes selfcondensation of aldehydes is observed. Sometimes this consecutive reaction is favored as in the production of 2-ethyl hexanol. But synthetic applications of tandem hydroformylation/aldol reactions seem to be limited due regiose-lectivity problems of a mixed aldol reaction (Scheme 28). However, various tandem hydroformylation/intramolecular mixed aldol reactions have been described. 

The findings from the evacuation experiment confirmed the interpretation that the observed slight deactivation over time was not due to catalyst decomposition, as an accompanying decrease in activity and selectivity otherwise would have been observed. Instead, we expected the formation of aldol products 2-ethyl-hexanal and 2-ethyl-hexanol to be of relevance, as traces of these high boiling side products were observed at particular high conversions. 

The isolated dimethyl sebacate can be sold commercially as is or optionally hydrolyzed to sebacic acid. If a higher molecular weight plasticizer diester is required, a transesterification with -ethyl hexanol, for example, gives the desired product plus two equivalents of methanol which is recycled back to the oxycarbonylation reaction. If the free acid is desired, dimethyl sebacate hydrolysis to sebacic acid is carried out using a strong mineral acid such as sulfuric acid. Hydrolysis is nearly quantitative with a selectivity of about 99.5% to diacid and. 5% to the half-ester acid product. Additional recrystallization is used to improve purity if required. 

The hydroformylation reaction, also known as the oxo reaction, is used extensively in commercial processes for the preparation of aldehydes by the reaction of one mole of an olefin with one mole each of hydrogen and carbon monoxide. The most extensive use of the reaction is in the preparation of normal- and iso-butyraldehyde from propylene. The ratio of the amount of the normal aldehyde product to the amount of the iso aldehyde product typically is referred to as the normal to iso (N I) or the normal to branched (N B) ratio. In the case of propylene, the normal- and iso-butyraldehydes obtained from propylene are in turn converted into many commercially-valuable chemical products such as n-butanol, 2-ethyl-hexanol, trimethylol propane, polyvinylbutyral, n-butyric acid, iso-butanol, neo-pentyl glycol,... 

As many as 70 products were at one time produced commercially from ethanol. Some of these downstream products are butanol, 2-ethyl hexanol, crotonaldehyde, butyraldehyde, acetaldehyde, acetic acid, butadiene, sorbic acid, 2-ethylbutanol, ethyl ether, many esters, ethanol-glycol ethers, acetic anhydride, vinyl acetate, ethyl vinyl ether, even ethylene gas. Many of these products are now more economically made from other feedstocks such as ethylene for acetaldehyde and methanol-carbon monoxide for acetic acid. Time will tell when a revival of biologically-oriented processes will offer lower-cost routes to at least the simpler products. 

This section deals with the conceptual design of a catalytic distillation process for the esterification of lauric acid (LA) with 2-ethyl-hexanol (2EtH). Laboratory experiments showed that a superacid sulfated zirconia catalyst exhibits good activity over a large interval, from 130 to 180 °C with no ether formation. On the contrary, the catalyst is sensitive to the presence of free liquid water. Raw materials are lauric acid and 2-ethylhexyl alcohol of high purity. The conversion should be over 99.9%, because the product is aimed at cosmetic applications. 

Further improvement in the technology of methyl fatty ester synthesis can be achieved by dual esterification [4], This takes advantage of the fact that the sulfated zirconia catalyst has similar activity for normal alcohols, over the series C1-C8. However, methanol manifests about twice the activity [20], The removal of water produced by the esterification with methanol is solved simply, by employing a heavy alcohol immiscible with water, such as 2-ethyl-hexanol, which acts simultaneously as a reactant and an entrainer. As a result, the two fatty esters are obtained in the bottom product in the desired ratio by adjusting the feeds. For example, in a preferable operation mode the ratio of fresh feed reactants is acid methanol 2-ethyl-hexanol 1 0.8 0.2. 

The use of alkali metal oxide catalysts for aldol condensation reactions has been examined for the production of 2-ethylhexenal from butanal [34]. When coupled to a hydrogenation catalyst the system can produce the plasticizer alcohol 2-ethyl-hexanol directly. When isobutyraldehyde was used as the feed to a silica-supported sodium oxide catalyst, no products were formed but a significant amount of carbon was deposited on the catalyst and in the reactor (Scheme 21.2). 

The high thermal stability of the Deloxan ASP catalysts is also a key factor when looking at the achieved conversion rates in the esterification of phthalic anhydride with various alcohols, e.g. 1-octanol or 2-ethyl-hexanol, to yield di-octyl-phthalates (reaction 1) that are used as plasticizers. Product yields of > 99% for the diester are obtained for residence times between 30-50 minutes, at temperatures between 150°C and 180°C. 

Apart from propylene, which can be used as a raw material for the production of 2-ethyl hexanol, the mam olefins employed in the Oxo synthesis of higher alcohols result from ... 

Tables 9.15 and 9.16 summarize the main economic data available in the literature or recalculated, concerning the production of 2-ethyl hexanol, isooctanols in mixtures, or higher alcohols by different industrial processes.

The consumption of 0x0 alcohol products in the United States, western Europe, and Japan for 1993 is shown in Table 7 [33], Table 7 shows that more than 50% of the total demand for 0x0 product is for n-butyraldehyde. Most is used to produce 2 ethyl hexanol. This is followed by demand for detergent alcohols, plasticizers, and the rest. The highest volume products have the lowest margin. The most profitable are the specialty 0x0 products which constitute the lower volumes. Most of the future growth is expected to be in the specialty products as well. 

Distillation with reaction, where the normal process is coupled with a liquid phase reaction, is also interesting and esterifications of certain alcohols with acids are typical industrial applications. These include, among others the homogeneously catalyzed butyl acetate process and the production of the plasticizer di-octyl-phthalate from phthalic anhydride and 2-ethyl-hexanol. However, the subject which involves both product formation and separation aspects has not usually been treated in the literature relating specifically to "mass transfer with reaction". 

Sulfosuccinates are used in many different fields of application. For comprehensive overviews, see Refs 18,20-22. Sulfosuccinic acid dialkyl esters are weakly foaming surfactants with good wetting power. In particular, products on the basis of octanol or 2-ethyl hexanol are distinguished by their outstanding wetting properties. Even at a low concentration, they can cause a considerable reduction in the surface tension of aqueous solutions [21]. Sulfosuccinic acid dialkyl esters, on the basis of alcohols with fewer than nine carbon atoms, are water soluble. Branched alkyl groups increase the solubility [23],... 

Titanium alkoxides feature as catalysts in the esterification of succinic, adipic, azelaic, and sebacic acids with 2-ethyl hexanol and in the production of acetate... 

An example with huge economic relevance is the manufacture of 2-propyl-heptanol (2-PH) as a component of plasticizer alcohols and, on a smaller scale, for use in cosmetics [9]. On an industrial scale, the transformation is commonly conducted as a three-step approach starting with the hydroformylation of isomeric butenes, subsequent aldol reaction of formed -valeraldehyde, and, finally, combined hydrogenation of the C-C double bond and aldehyde group [10]. In a similar process, the production of the plasticizer alcohol 2-ethyl-hexanol (2-EH) is carried out [11, 12]. 

The terephthalate plasticizer DEHTP, first commercialized around 1975 as Eastman DOTP, is very similar in structure to DEHP except that the substitution of the aromatic ring is at the 1,4 position versus the 1,2 position of the aromatic ring. The structure of DEHTP is also shown in Pig. 24.1. Terephthalates are prepared by the esterification of terephthaUc acid or by the transesterification of dimethyl terephthalate with aliphatic alcohols such as butanol or 2-ethyl hexanol. Although DEHTP can be produced from terephthalic acid in a traditional DEHP esterification plant with minor modifications to the process, this process is not as efficient as the esterification of phthalic anhydride and manufacturing capacity reductions of >50% are realized. Transesterification of dimethyl terephthalate is a much faster reaction. However, this process will require significant process modifications to a traditional DEHP manufacturing unit. One benefit with this chemistry is that it does not lead to a significant drop in production capacity. The main problem with this route is the limited availability of dimethyl terephthalate in many locations. 

This reaction has been previously studied, both inthe gas (13-14) and liquid phase (15-17) as the main products, 2 ethyl hexanal (HAL) and 2 ethyl hexanol (HOL) have some industrial interest. HOL is used during the production of dioctylphta1 ate, for the manufacturing of PVC softeners, whereas the octanoic acid can be obtained by oxidation of HAL. 

Direct, acid catalyzed esterification of acryhc acid is the main route for the manufacture of higher alkyl esters. The most important higher alkyl acrylate is 2-ethyIhexyi acrylate prepared from the available 0x0 alcohol 2-ethyl-1-hexanol (see Alcohols, higher aliphatic). The most common catalysts are sulfuric or toluenesulfonic acid and sulfonic acid functional cation-exchange resins. Solvents are used as entraining agents for the removal of water of reaction. The product is washed with base to remove unreacted acryhc acid and catalyst and then purified by distillation. The esters are obtained in 80—90% yield and in exceUent purity. 

The propylene-based chemicals, n- and isobutanol and 2-ethyl-1-hexanol [104-76-7] (2-EH) dominate the product spectmm. These chemicals represent 71% of the world s total oxo chemical capacity. In much of the developed world, plasticizers (qv), long based on 2-EH, are more often and more frequendy higher molecular weight, less volatile Cg, and C q alcohols such as isononyl alcohol, from dimerized normal butenes isodecanol, from propylene trimer and 2-propyl-1-heptanol, from / -butenes and aldol addition. Because of the competition from the higher molecular weight plasticizer alcohols,... 

In excess of a million metric tons of 0x0 products are produced in the United States annually. They are used in the manufacture of plasticizers, solvents, and detergents. The principal 0x0 alcohol product, 2-ethyl-1-hexanol [104-76-7] is made from propylene [115-07-1] and represents about 75% of the 0x0 market. 

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