Aldehydes propionaldehyde

Aldehydes Acetaldehyde Acrolein (inhibited) Butyraldehyde Dec aldehyde Ethylhexald ehyde Formaldehyde Glutaraldehyde Solution Glyoxal Solution Methylbutyraldehyde Octyl Aldehyde Pentyl Aldehyde Propionaldehyde Valeraldehyde... 

Yoshida et al. [356] show the presence of O" and OJ on V2Os supported by Si02. With strong reduction, it is mainly O. It was proved that reaction of 02 with propene gives rise to aldehydes (propionaldehyde, acrolein and formaldehyde) at temperatures below 150°C. Yoshida et al. [357] confirm this and find that oxygen at room temperature is mainly adsorbed as molecular oxygen, only 10% is the sum of O and 02. O" is the oxygen species reactive towards carbon monoxide, 02 is not. 

Among the war gases various examples occur of the influence of the unsaturated bond. Thus, acrolein CH = CH—CHO, has strongly irritant properties, while the corresponding saturated aldehyde, propionaldehyde, CH3—CH —CHO is innocuous. Similarly, /3 chlorovinyl dichloroarsine. Cl—CH = CH—AsCl, is a powerful vesicant, while the corresponding saturated compound, jS chloroethyl dichloroarsine. Cl—CHj—CHg—AsCl, has only weak vesicatory properties. ... 

The main by-products formed are carbon dioxide, alcohols (ethanol, butanol, etc.) aldehydes (propionaldehyde, n- and isobutyraldehydes), acids (formic, propionic etc.), esters (methyl formate and acetate), and ethers (dimethyl ether, etc.). Some of them, obtained in large quantifies (methyl acetate and dimethyl ether), can be recycled. 

Interestingly, the reaction outcome can be improved in terms of yield and enantioselectivity by applying high pressure to the reaction conditions, albeit at levels unreachable with standard to-date technical equipment. Entirely aldehyde-based versions of the proline-catalysed Mannich reaction are also possible and provide access to q n-y-amino alcohols after subsequent reduction in excellent enantioselectivities (Scheme 5.12). To avoid the favoured cross-aldol or self-Mannich side reactions of the aldehyde, propionaldehyde needed to be added slowly to the reaction mixture. 

In case of low boiling aldehydes (propionaldehyde, butyraldehyde, etc) and carbonyls of low volatility (Rh-carbonyls, phosphine modified cobalt or rhodium catalysts), the aldehydes may be separated from the reaction product by flash distillation [150]. In this operation the metal carbonyls remain in the bottoms. Depending on temperature, length of treatment and stability of the carbonyls, varying amounts of them are decomposed. The corresponding metals formed also remain in the bottoms. This method is limited to laboratory operations (with the exception of phosphine modified catalyst — see chapter on modified catalysts). It cannot be recommended for cobalt carbonyls since they are too volatile. 

Higher Aliphatic Aldehydes Propionaldehyde and isobutyraldehyde reiict with aqueous formaldeliyde in a manner analogous to that observed in the case of acetaldehyde. 

The glycidic esters are of interest primarily because upon hydrolysis aud decarboxylation they aflFord aldehydes (if ClCHjCOOEt is used) or ketones (if substituted chloroacetic esters- ClCHRCOOEt are employed) having a higher carbon content than the original aldehyde or ketone. Thus (I) gives o-phenyl-propionaldehyde or hydratropaldehyde (II) ... 

Starting from propionaldehyde the aldehyde H2C=CH-CH=C(CH3)CH=0 was obtained in an impure state and in moderate yield. Its precursor H2C=C=CH-CH(CH3)CH=0 was present in traces only. 

When the aldehyde group is directly attached to a carbon atom of a ring system, the suffix -carbaldehyde is added to the name of the ring system, e.g., 2-naphthalenecarbaldehyde. When the aldehyde group is separated from the ring by a chain of carbon atoms, the compound is named (1) as a derivative of the acyclic system or (2) by conjunctive nomenclature, for example, (1) (2-naphthyl)propionaldehyde or (2) 2-naphthalenepropionaldehyde. 

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. 

The mechanism of the cobalt-cataly2ed oxo reaction has been studied extensively. The formation of a new C—C bond by the hydroformylation reaction proceeds through an organometaUic intermediate formed from cobalt hydrocarbonyl which is regenerated in the aldehyde-forrning stage. The mechanism (5,6) for the formation of propionaldehyde [123-38-6] from ethylene is illustrated in Figure 1. 

Union Carbide Corp. (Texas City, Tex.) propionaldehyde and valer-aldehyde 91 Rli... 

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 ... 

This procedure is representative of a new general method for the preparation of noncyclic acyloins by thiazol ium-catalyzed dimerization of aldehydes in the presence of weak bases (Table I). The advantages of this method over the classical reductive coupling of esters or the modern variation in which the intermediate enediolate is trapped by silylation, are the simplicity of the procedure, the inexpensive materials used, and the purity of the products obtained. For volatile aldehydes such as acetaldehyde and propionaldehyde the reaction Is conducted without solvent in a small, heated autoclave. With the exception of furoin the preparation of benzoins from aromatic aldehydes is best carried out with a different thiazolium catalyst bearing an N-methyl or N-ethyl substituent, instead of the N-benzyl group. Benzoins have usually been prepared by cyanide-catalyzed condensation of aromatic and heterocyclic aldehydes.Unsymnetrical acyloins may be obtained by thiazol1um-catalyzed cross-condensation of two different aldehydes. -1 The thiazolium ion-catalyzed cyclization of 1,5-dialdehydes to cyclic acyloins has been reported. 

There is a compound called propanol with structural formula CH3CH2CH2OH. If it is oxidized carefully, an aldehyde called propionaldehyde is obtained. Vigorous oxidation gives an acid called propionic acid. Draw structural formulas like those shown in Figures 18-6 and 18-7 for propionaldehyde and propionic acid. 

Figure 5.6 Alcohols, aldehydes, ketones and acids 15, ethylene glycol 16, vinyl alcohol 17, acetaldehyde 18, formaldehyde 19, glyoxal 20, propionaldehyde 21, propionaldehyde 22, acetone 23, ketene 24, formic acid 25, acetic acid 26, methyl formate. (Reproduced from Guillemin et at. 2004 by permission of Elsevier)...

The simplest a,/3-unsaturated aldehyde, acrolein, gives nearly quantitative yields of the hydrogenation product propionaldehyde under hydroformylation conditions. Most of the research has been conducted on acetal or acetate derivatives. 

The cobalt-catalyzed hydroformylation of acrolein diacetate in ethanol proceeded in a complicated fashion. The products obtained are listed in Table XXVI. These products are rationalized by the following sequence The initial products formed were m-aldehyde (l,l-diacetoxy-3-formylpro-pane, ca. 60%), isoaldehyde (1,1 -diacetoxy-2-formylpropane, 5-10%) and propionaldehyde diacetate, ca. 5%. In the alcohol solvent, the aldehydes were converted to the corresponding acetals. A portion of the n-aldehyde was converted to 2,5-diethoxytetrahydrofuran by acid catalysis, and the isoaldehyde was thermally decomposed to 2-methyl-3-acetoxyacrolein. 

A closer examination by ex situ analysis using NMR or gas chromatography illustrates that intrazeolite reaction mixtures can get complex. For example photooxygenation of 1-pentene leads to three major carbonyl products plus a mixture of saturated aldehydes (valeraldehyde, propionaldehyde, butyraldehyde, acetaldehyde)38 (Fig. 33). Ethyl vinyl ketone and 2-pentenal arise from addition of the hydroperoxy radical to the two different ends of the allylic radical (Fig. 33). The ketone, /i-3-penten-2-one, is formed by intrazeolite isomerization of 1-pentene followed by CT mediated photooxygenation of the 2-pentene isomer. Dioxetane cleavage, epoxide rearrangement, or presumably even Floch cleavage130,131 of the allylic hydroperoxides can lead to the mixture of saturated aldehydes. 

---