Butyraldehydes reaction

HYDROGENATION OF CROTONALDEHYDE TO n-BUTYRALDEHYDE REACTION KINETICS IN A SLURRY REACTOR... 

Aldehydes fiad the most widespread use as chemical iatermediates. The production of acetaldehyde, propionaldehyde, and butyraldehyde as precursors of the corresponding alcohols and acids are examples. The aldehydes of low molecular weight are also condensed in an aldol reaction to form derivatives which are important intermediates for the plasticizer industry (see Plasticizers). As mentioned earlier, 2-ethylhexanol, produced from butyraldehyde, is used in the manufacture of di(2-ethylhexyl) phthalate [117-87-7]. Aldehydes are also used as intermediates for the manufacture of solvents (alcohols and ethers), resins, and dyes. Isobutyraldehyde is used as an intermediate for production of primary solvents and mbber antioxidants (see Antioxidaisits). Fatty aldehydes Cg—used in nearly all perfume types and aromas (see Perfumes). Polymers and copolymers of aldehydes exist and are of commercial significance. 

Another attractive commercial route to MEK is via direct oxidation of / -butenes (34—39) in a reaction analogous to the Wacker-Hoechst process for acetaldehyde production via ethylene oxidation. In the Wacker-Hoechst process the oxidation of olefins is conducted in an aqueous solution containing palladium and copper chlorides. However, unlike acetaldehyde production, / -butene oxidation has not proved commercially successflil because chlorinated butanones and butyraldehyde by-products form which both reduce yields and compHcate product purification, and also because titanium-lined equipment is required to withstand chloride corrosion. 

Propylene-Based Routes. The strong acid-catalyzed carbonylation of propylene [115-07-1] to isobutyric acid (Koch reaction) followed by oxidative dehydration to methacrylic acid has been extensively studied since the 1960s. The principal side reaction in the Koch reaction is the formation of oligomers of propylene. Increasing yields of methacrylic acid in the oxydehydration step is the current focus of research. Isobutyric acid may also be obtained via the oxidation of isobutyraldehyde, which is available from the hydroformylation of propylene. The -butyraldehyde isomer that is formed in the hydroformylation must be separated. 

The search for catalyst systems which could effect the 0x0 reaction under milder conditions and produce higher yields of the desired aldehyde resulted in processes utilizing rhodium. Oxo capacity built since the mid-1970s, both in the United States and elsewhere, has largely employed tertiary phosphine-modified rhodium catalysts. For example, over 50% of the world s butyraldehyde (qv) is produced by the LP Oxo process, technology Hcensed by Union Carbide Corporation and Davy Process Technology. 

Fig. 4. Mechanism for the TPP-modified rhodium-catalyzed oxo reaction of propylene to -butyraldehyde.

Aldol reaction of campholenic aldehyde with propionic aldehyde yields the intermediate conjugated aldehyde, which can be selectively reduced to the saturated alcohol with a sandalwood odor. If the double bond in the cyclopentene ring is also reduced, the resulting product does not have a sandalwood odor (161). Reaction of campholenic aldehyde with -butyraldehyde followed by reduction of the aldehyde group gives the aHyUc alcohol known commercially by one manufacturer as Bacdanol [28219-61 -6] (82). 

Manufacture of thiophene on the commercial scale involves reactions of the two component method type wherein a 4-carbon chain molecule reacts with a source of sulfur over a catalyst which also effects cyclization and aromatization. A range of suitable feedstocks has included butane, / -butanol, -butyraldehyde, crotonaldehyde, and furan the source of sulfur has included sulfur itself, hydrogen sulfide, and carbon disulfide (29—32). 

Manufacture. PVBs are manufactured by a variety of two-stage heterogeneous processes. In one of these an alcohol solution of poly(vinyl acetate) and an acid catalyst are heated to 60—80°C with strong agitation. As the poly(vinyl alcohol) forms, it precipitates from solution (77). Ethyl acetate, the principle by-product, is stripped off and sold. The precipitated poly(vinyl alcohol) is washed to remove by-products and excess acid. The poly(vinyl alcohol) is then suspended in a mixture of ethyl alcohol, butyraldehyde, and mineral acid at temperatures above 70°C. As the reaction approaches completion the reactants go into solution. When the reaction is complete, the catalyst is neutralized and the PVB is precipitated from solution with water, washed, centrifuged, and dried. Resin from this process has very low residual vinyl acetate and very low levels of gel from intermolecular acetalization. 

Poly(vinyl butyral), prepared by reacting poly(vinyl alcohol) with -butyraldehyde, finds wide appHcation as the interlayer in safety glass and as an adhesive for hydrophilic surfaces (161). Another example is the reaction of poly(vinyl alcohol) with formaldehyde to form poly(vinyl formal), used in the production of synthetic fibers and sponges (162). 

The principal commercial source of 1-butanol is -butyraldehyde [123-72-8] obtained from the Oxo reaction of propylene. A mixture of n- and isobutyraldehyde [78-84-2] is obtained in this process this mixture is either separated initially and the individual aldehyde isomers hydrogenated, or the mixture of isomeric aldehydes is hydrogenated direcdy and the n- and isobutyl alcohol product mix separated by distillation. Typically, the hydrogenation is carried out in the vapor phase over a heterogeneous catalyst. For example, passing a mixture of n- and isobutyraldehyde with 60 40 H2 N2 over a CuO—ZnO—NiO catalyst at 25—196°C and 0.7 MPa proceeds in 99.95% efficiency to the corresponding alcohols at 98.6% conversion (7,8) (see Butyraldehydes Oxo process). 

Several species of bacteria under suitable conditions cause / -butyraldehyde to undergo the Canni22aro reaction (simultaneous oxidation and reduction to butyric acid and butanol, respectively) this reaction can also be cataly2ed by Raney nickel (7). The direct formation of butyl butyrate [109-21 -7] or isobutyl isobutyrate [97-85-8](Vish.ch.erik.o reaction) from the corresponding aldehyde takes place rapidly with aluminum ethylate or aluminum butyrate as catalyst (8). An essentially quantitative yield of butyl butyrate, CgH2 02, from butyraldehyde has been reported usiag a mthenium catalyst, RuH,[P(C,H,)3], (9). 

Hydrogen chloride or a few drops of hydrochloric acid cataly2e the conversion of //-butyraldehyde iato the trimer, parabutyraldehyde, C22H24O2, (2,4,6-tripropyl-l,3,5-trioxane [56769-26-7] (1). The reaction is reversed by heating the parabutyraldehyde ia the presence of acid. Anhydrous hydrogen chloride at —40°C converts //-butyraldehyde iato l,l -dichlorodibutyl ether, (2) ia 70—75% yield (10). 

In the presence of dilute sodium or potassium hydroxide, //-butyraldehyde undergoes the aldol reaction to form 2-ethyl-3-hydroxyhexanal [496-03-7] which, on continued heating, is converted iato 2-ethyl-2-hexenal [26266-68-2]. Hydrogenation of the latter gives 2-ethyl-1-hexanol/7 (94-7%., aptincipal plastici2er alcohol. 

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). 

Reaction of poly(vinyl alcohol) [9002-89-5] with //-butyraldehyde yields poly(vinyl butyral) [63148-65-2] (PVB), a commercially important resia. 

The earhest commercial route to -butyraldehyde was a multistep process starting with ethanol, which was consecutively dehydrogenated to acetaldehyde, condensed to crotonaldehyde, and reduced to butyraldehyde. In the late 1960s, production of -butyraldehyde (and isobutyraldehyde) in Europe and the United States switched over largely to the Oxo reaction of propylene. 

The earhest modification of the Oxo process (qv) employed cobalt hydrocarbonyl, HCo(CO)4, as catalyst. The reaction was carried out in the Hquid phase at 130—160°C and 10—20 MPa (1450—2900 psi) to give a ratio of n- to isobutyraldehyde of between 2 1 to 4 1. / -Butyraldehyde, the straight-chain isomer and the precursor of 2-ethylhexanol, was the more valuable product so that a high isomer ratio of n- to isobutyraldehyde was obviously advantageous. 

Garbonylation of Olefins. The carbonylation of olefins is a process of immense industrial importance. The process includes hydroformylation and hydrosdylation of an olefin. The hydroformylation reaction, or oxo process (qv), leads to the formation of aldehydes (qv) from olefins, carbon monoxide, hydrogen, and a transition-metal carbonyl. The hydro sdylation reaction involves addition of a sdane to an olefin (126,127). One of the most important processes in the carbonylation of olefins uses Co2(CO)g or its derivatives with phosphoms ligands as a catalyst. Propionaldehyde (128) and butyraldehyde (qv) (129) are synthesized industrially according to the following equation ... 

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. 

However, the 0x0 reaction starting frompropylene and proceeding via the hydrogenation of butyraldehyde, has become the more widely employed commercial route for preparing / -butanol (see BuTYL ALCOHOLS Oxo PROCESS). 

A radical reaction is sometimes observed to compete with the particularly slow acid hydrolyses of diaziridines derived from formaldehyde. With other diaziridines the radical reaction can be made to predominate by using HCl in carbon tetrachloride solution. Acetaldehyde, butyraldehyde, butylamine and ammonia are obtained from (160) (64CB49). 

The reaction can also be carried out using smaller amounts of 1-methylpyrrole (0.113 mol), butyraldehyde (0.113 mol) and a solvent (245 ml acetonitrile, ACS grade) 1n a somewhat larger reaction vessel. After 17 hr of photolysis, and after removal of the volatile material and distillation of the remaining oil under reduced pressure, 4-5 g of the alcohol 1s Isolated. 

A 600-mL, three-necked, round-bottomed flask 1s equipped with a mechanical stirrer, a short gas inlet tube, and an efficient reflux condenser fitted with a potassium hydroxide drying tube. The flask is charged with 13.4 g (0.05 mol) of 3-ben2y1-5-(2-hydroxyethyl)-4-methyl-l,3-th1azol1um chloride (Note 11, 72.1 g (1.0 mol) of butyraldehyde (Note 2). 30.3 g (0.3 mol) of triethylamine (Note 2), and 300 raL of absolute ethanol. A slow stream of nitrogen (Note 3) is begun, and the mixture is stirred and heated In an oil bath at 80°C. After 1.5 hr the reaction mixture is cooled to room temperature and concentrated by rotary evaporation. The residual yellow liquid Is poured Into 500 mL of water contained 1n a separatory funnel, and the flask is rinsed with 150 mL of dichloromethane which is then used to extract the aqueous mixture. The aqueous layer is extracted with a second 150-mL portion of... 

The procedure may be conducted on a larger scale in which case the proportion of catalyst and base are reduced. The submitters report that they obtained 169 g (78 ) of butyroin from 216.3 g (3.0 mol) of butyraldehyde, 26.8 (0.1 mol) of thiazolium catalyst, 60.6 g (0.6 mol) of triethylamlne, and 600 mL of absolute ethanol. Although the scale may be increased further, appropriate precautions should be taken to control the reaction. For example, the aldehyde may be added in portions or the flask may be cooled initially. 

In a typical process 140 parts of fully hydrolysed poly(vinyl alcohol) are suspended in 800 parts of ethanol 80 parts of butyraldehyde and 8 parts of sulphuric acid are added and the reaction is carried out at about 80 C for 5-6 hours. 

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