Aldolization of butyraldehyde

Ethylhexanol is usually produced by subsequent aldolization of butyraldehyde produced in the oxo reaction followed by hydrogenation of the intermediate unsaturated aldehyde.89 In Esso s Aldox process, however, in situ aldol condensation is effected by suitable promoters.11 Magnesium ethoxide and soluble zinc compounds are recommended to promote controlled aldolization during the oxo reaction. The Shell variant uses potassium hydroxide. Serious disadvantages (mixed aldolization with the branched aldehyde, problems associated with recycling of the additives), however, prevented wider use of the Aldox process. 

The feasibility of the alternative process using heterogeneous catalysis was investigated by screening several anion-exchange resin catalysts [16] and optimizing the reaction conditions for the aldolization of butyraldehyde and propionaldehyde with formaldehyde the phase distribution coefficients of the... 

Table 1 The values of the slopes of the Cp-Cx (aldol - ethylacrolein) curves for the aldolization of butyraldehyde in methanolic and aqueous environment... 

Serra-Holm, T Salmi, P Maki-Arvela, E Paatero, L P Lindfors. Comparison of Activity and Selectivity of Weakly Basic Anion-Exchange Catalysts for the Aldolization of Butyraldehyde with Formaldehyde. Org Process Res Devel 5 368-375,2001. 

Butyraldehyde undergoes stereoselective crossed aldol addition with diethyl ketone [96-22-0] ia the presence of a staimous triflate catalyst (14) to give a predominantiy erythro product (3). Other stereoselective crossed aldol reactions of //-butyraldehyde have been reported (15). 

Ethylhexanal, the reduced aldol condensation product of //-butyraldehyde, is converted into 2-ethylhexanoic acid [149-57-5] which is converted primarily into salts or metal soaps. These are used as paint driers and heat stabili2ers for poly(vinyl chloride). 

Trimethylolpropane (TMP), the reduced crossed aldol condensation product of //-butyraldehyde and formaldehyde, competes in many of the same markets as glycerol (qv) and pentaerythritol. The largest market for TMP is as a precursor in unsaturated polyester resins, short-oil alkyds, and urethanes for surface coatings (see Alkyd resins). 

Methyl amyl ketone, derived from the crossed aldol condensation of -butyraldehyde and acetone, is used predominandy as a high soHds coatings solvent. It is also employed as a replacement for the very toxic 2-ethoxyethyl acetate [111 -15-9J. 

Neo acids are prepared from selected olefins using carbon monoxide and acid catalyst (4) (see Carboxylic Acids, trialkylacetic acids). 2-EthyIhexanoic acid is manufactured by an aldol condensation of butyraldehyde followed by an oxidation of the resulting aldehyde (5). Isopalmitic acid [4669-02-7] is probably made by an aldol reaction of octanal. 

Results of tracer impulse input data for aldolization of n-butyraldehyde are in the first two columns of the table. The tracer was carbon-14 tagged octadecane. Find the variance and the skewness. 

Ethylhexanol is produced by aldol condensation of butyraldehyde followed by reduction. It can also be made in one step from propylene and synthesis gas converted to butanols and 2-ethylhexanol without isolating the butyraldehydes. See Chapter 10, Section 6. 

The order of activity per unit surface area was equal to that in the case of selfcondensation of acetone and in agreement with the order of basicity of the solids, namely, SrO > CaO > MgO. However, the authors found that the rate-determining step for aldol condensation of n-butyraldehyde is the a-hydrogen abstraction by the active sites, which are the surface ions. The differences in rate-determining step and active sites in the condensation of butyraldehyde and aldol condensation of the acetone were attributed to differences in acidity of the a-hydrogen in the two molecules. CaO was slightly more active than MgO at 273 K after a reaction time of 1 h, maximum conversions of 41% were observed with selectivities to 2-ethyl-3-hydroxy-hexanal and to the corresponding Tishchenko reaction product (2-ethyl-3-hydroxy- -hexyl butyrate) of 39.8 and 56.9%, respectively. 

Shu and co-workers (35) identified 2-isobutyl-3,5-diisopropylpyridine, 2-pentyl-3,5-dimethylpyridine, and its dihydro derivative obtained under similar conditions. Sultan (29) confirmed the presence of 3,5-diethyl-2-propylpyridine in a model system consisting of butyraldehyde and ammonium sulfide. Our proposed mechanism of their formation (20) consists of three steps 1) aldol condensation of the starting aldehydes to 2,4-alkadienals, 2) imine formation with ammonia, and 3) subsequent cyclization and oxidation to corresponding pyridines. An alternate mechanism, suggested by Shu and co-workers (33), takes into consideration the isolated dihydro derivatives. Hwang and co-workers described another dihydro derivative (19, R = Bu, R = R" = Pr, R= H) (37). 

Ethyl alcohol has been made by the hydration of ethylene (9) since 1930. Like isopropyl alcohol, part of the output is used as a solvent, but most is converted to other oxygenated chemicals. Its most important raw material use is conversion to acetaldehyde by catalytic air oxidation. Acetaldehyde, in turn, is the raw material source of acetic acid, acetic anhydride, pentaerythritol, synthetic n-butyl alcohol (via aldol condensation), butyraldehyde, and other products. Butyraldehyde is the source of butyric acid, polyvinyl butyral resin, and 2-ethylhexanol (octyl alcohol). The last-named eight-carbon alcohol is based on the aldol condensation of butyraldehyde and is used to make the important plasticizer di-2-ethylhexyl phthalate. A few examples of the important reactions of acetaldehyde are as follows ... 

Zhang, G., Hattori, H. and Tanabe, K. Aldol addition of butyraldehyde over solid base catalysts, Bull. Chem. Soc. Jpn., 1989, 62, 2070-2072. 

The mechanism proposed so far takes account of the induction period and initial stages of the reaction only, and it is difficult to see how it can account for the large amount of hydroperoxide decomposed by the sulfur compound. However, Tetralin hydroperoxide is decomposed catalytically by acids (5). Although in the absence of dilauryl thiodipropionate the decomposition of Tetralin hydroperoxide in the presence of acetic acid at 70 °C. was very slow, if the acid species is a much stronger acid than acetic—e.g., a sulfonic acid as seems likely from the nature of the products of the reaction, the rate of acid-induced decomposition may be comparable with the rate of decomposition by the sulfur compound. Some evidence that acid-induced decomposition does occur at some stage in the over-all reaction is found in the presence of an ortho substituted aromatic compound in the solid product of the reaction. The acid catalyzed decomposition of Tetralin hydroperoxide follows the path of Reaction 14 (5) to give y-(o-hydroxyphenyl)butyraldehyde. This forms a brown resin which is mainly the aldol of this aldehyde (cfthe resin obtained in this work). 

Celanese GmbH/Krupp Uhde Ethylhexanol 2 n-Butyr aldehyde Aldolization of n-butyraldehyde with aqueous caustic soda yields 2-ethylhexanol NA NA... 

The relative rate increase with LiC104 (3 mol %) in CH2CI2 was also observed in a case involving the aldolization of A jA -dibenzyl-protected aminoaldehyde, where anti-product predominates, as a result of non-chelation control. When attempted in Et20, the transformation is successful only when 5.0 m LPDE is used. Moreover, a reaction time of 18 h at room temperature sufficed for complete conversion of iso-butyraldehyde, while reacting less rapidly to the desirable product [108]. 

CAS 104-76-7. CH3(CH2)3CHC2H5CH2OH. Properties Colorless liquid. D 0.83 (20C), bp 183.5C, fp -76C, vap press 0.36 (20C), refr index 1.4300 (20C), bulk d 6.9 lb/gal (20C), flash p 178F (81.1C). Miscible with most organic solvents, slightly soluble in water. Combustible. Derivation (a) Oxo process from propylene and synthesis gas (b) aldolization of acetaldehyde or butyraldehyde, followed by hydrogenation (c) from fermentation alcohol. 

Although isooctanol is slightly cheaper than 2—ethylhexanol, it is still considered more important due to the slightly higher volatility of diisooctyl phthalate, the unavailability of heptene, and the better odor of di-2-ethylhexyl phthalate. 2—Ethylhexanol is produced by the aldolization of n-butyraldehyde and subsequent hydrogenation, whereas isooctanol is made by the oxo reaction... 

This consists in the aMofizstion of butyraldehyde, followed by the dehydration and hydrogenation of the aldoL The butyraldehyde can be obtained cither by the aldolization of acetaldehyde, or by Oxo synthesis of propylene, which is the more widely used method. These different possibilities can be summarized as follows ... 

The aldolic condensation of butyraldehyde occurs in the presence of caustic soda, which acts as a catalyst (Ruhrchemie process). The system operates in this case between 80 and 130 C and between 03 and 1.106 Pa absolute. The continuous removal of one molecule of water yields 2-ethylhexenal, which is hydrogenated in the presence of a nickel catalyst between 100 and 15IPC and between 5 and 10.10 Pa absolute. 

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