Isobutyraldehyde, from oxidation

Various aldehydes are encountered in wine. The most abundant is acetaldehyde which is both a product of yeast metabolism and an oxidation product of ethanol. Glyoxylic acid, resulting from oxidation of tartaric acid, especially catalyzed by metal ions (Fe, Cu) or ascorbic acid, can also be present. Other aldehydes reported to participate in these reactions include furfural and 5-hydroxymethylfurfural that are degradation products of sugar and can be extracted from barrels (Es-Safi et al. 2000), vanillin which also results from oak toasting, isovaleraldehyde, benzaldehyde, pro-pionaldehyde, isobutyraldehyde, formaldehyde and 2-methylbutyraldehyde which are present in the spirits used to produce fortified wines (Pissara et al. 2003). 

Isobutyraldehyde can be synthesized selectively from methanol and ethanol in one step by using titanium oxide-supported vanadium oxide (V205/Ti02) as a catalyst. This catalyst is also capable of synthesizing isobutyraldehyde from methanol and n-propyl alcohol. The reactions of methanol and w-propyl... 

Mixtures of perbutyric and butyric acid were formed during oxidation of butyral-dehyde in the presence of Co(OAc)2 [243]. The oxidation of n-butyraldehyde [243-245] and 2-ethyl hexaldehyde [246] are second order in aldehyde and follow expected radical pathways. Isobutyraldehyde was oxidized using ferrocene derivatives as catalysts [247,248]. In a typical experiment isobutyric acid was produced in 97% selectivity at 60% conversion of the aldehyde. Cobalt(II) and manganese(II) acetyl-acetonates have been used in a similar manner to prepare phenyl acetic acid from phenylacetaldehyde in good yield [249,250]. 

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. 

Butyric acid is made by air-oxidation of butyraldehyde, which is obtained by appHcation of the oxo synthesis to propylene. Isobutyric acid is made from isobutyraldehyde, a significant product in the synthesis of butyraldehyde (see Butyraldehydes). Butyraldehyde is also used to make 2-ethylhexanoic acid. 

Isobutyraldehyde, 4 459 14 584 animal toxicty, 4 466t effect of unsaturation on toxicity, 2 69t isobutyl alcohol manufacture from, 4 397 oxidative dehydrogenation of, 16 252 physical properties of, 4 459t quality specifications, 4 465t Isobutyraldol, butyraldehyde derivative, 4 461... 

B. 2,5-Dimethyl-2,4-hexanediol. Isobutylene oxide (7.2 g, 0.10 mol) (Note 7) is added dropwise from the pressure-equalizing funnel to the LDBB solution in THF at -78°C at such a rate (the addition lasts for 8-12 min) that the temperature inside the flask does not exceed -78°C. After all the epoxide has been added (8-11 min), the solution becomes deep red. After 5 more minutes of stirring, isobutyraldehyde (7.2 g,... 

Other chiral magnesium enolates derived from amides are known to react with aldehydes. For example, the aldol-type reaction of magnesium enolate of —)-trans-2-N,N-diethylacetamide-l,3-dithiolanes-5 -oxide with isobutyraldehyde affords a single diastere-omer in 82%. The relative stereochemistry of the adduct originates from a rigid transition state 87 where the oxygen atoms of the enolate and the aldehyde are coordinated to the magnesium atom. ... 

Chiral homoallylamines are valuable synthons for the preparation of biologically active components including P-amino carboxylic acids or esters, obtained by oxidation of the ally lie functionality.1-29 Because removal of the chiral auxiliary by hydrogenation leads to the loss of the allylic functionality, we developed alternative routes for the conversion of the adduct into the unprotected homoallylamines. As a typical example, (f ,f )-PGA-homoallylamine derived from isobutyraldehyde Hi was used to develop the so-called mroStrecker and the decarbonylation method for the conversion of (R)-phenylglycine amide protected homoallylamines into /V-benzylidene protected homoallylamines 15 (Scheme 25.7). 

A material with nitrogen-coordinated Ru was obtained from a silica-linked 2-(phenylazo)pyridine ligand. Results for cyclobutanol oxidation with 02 and the sacrificial oxidant isobutyraldehyde indicate that one- and two-electron oxidations occur simultaneously. The stability of the catalyst is not always guaranteed, probably because acids may be formed in oxidations of alcohols (284). Leaching problems are also encountered with a polymer-bound Ru Schiff base complex, used in oxidation of benzyl alcohol (285). 

Data for aliphatic aldehyde enolisation are very scarce, probably because the enolisation process is often complicated by oxidation and hydration. Nevertheless, the rate constants for base- and acid-catalysed iodination of R R2CHCHO were determined in aqueous chloroacetic acid-chloroacetate ion buffers (Talvik and Hiidmaa, 1968). The results in Table 4 show that alkyl groups R1 and R2 increase the acid-catalysed reactivity in agreement with hyperconjugative and/or inductive effects. This contrasts with aliphatic ketones for which steric interactions are important and even sometimes dominant. Data for base-catalysis are more difficult to interpret since a second a methyl group, from propionaldehyde to isobutyraldehyde, increases the chloroacetate-catalysed rate constant. This might result from a decrease of the a(C—H) bond-promoted hyperconjugative stabilisation of the carbonyl compound... 

Recently, Capon and Wu49 have reported the generation of secondary enamines from their TV-trimethylsilyl derivatives through hydrolysis. In DMSO-d6 (99% v/v)-D20 (1% v/v) solution, enamine 40 is converted to the TV-deuteriated enamine 41 quantitatively in 5-10 min at room temperature. The solution obtained is stable for several hours, but over a period of 2-3 days 41 is oxidized to acetone and iV-deuterio-TV-phenylforma-mide. On adding 15% (v/v) D20/DC1 (0.1 M) to the solution, enamine 41 is completely hydrolyzed to 2-[2//]isobutyraldehyde and aniline without detection of any intermediates. Enamine 42 is formed by the acid-catalyzed hydrolysis of 40 (Scheme 3). Similar results are obtained with other iV-aryl enamines. 

As shown in Scheme 15, cyclohexenone 117 was prepared from commercially available cyclohexanedione mono ethylene ketal 115 through a-phenylselenation followed by oxidation and selenoxide elimination. Compound 117 was treated with TBSOTf and the piperidine enamine of isobutyraldehyde to produce the conjugate addition product 118. Butenyl magnesium bromide was then added to the... 

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). 

Fig. 4. The variation with time of product formation during the oxidation of isobutene. Initial temperature = 293 °C initial pressure of isobutene = 100 torr initial pressure of oxygen = 100 torr. O, isobutene , oxygen , acetone , isobutene oxide , isobutyraldehyde , carbon dioxide , carbon monoxide , water. (From ref. 42.)...

Fig. 6. The variation of initial percentage yields with surface at 270 and 300 °C. isobutene , propionaldehyde , acetone cp, propene 6, isobutyraldehyde , methacrolein >, acetaldehyde , isobutene oxide. (From ref. 44.)...

Diels-Alder reactions of thiete 1,1-dioxides occur readily as exemplified by the syntheses of 151 ° and 152. Adducts of thiete 1,1-dioxide with tetraphenylcyclopentadienone or a-pyrone ° are thermally unstable. Thiete 1,1-dioxides also undergo 1,3-dipolar additions with diazoalkanes, (e.g., the formation of 153 from which the strained bicyclic thietane sulfone 154 is obtained) " nitrile oxides, and cycloadditions with the MA -dimethylenamine of isobutyraldehyde (e.g., the formation of 155). ° ... 

The major products from methyloxirane (propene oxide) are C2H5CHO, CH3COCH3 and CH2=CHCH20H [90], Similarly, isobutyraldehyde is the dominant product from isobutene oxide. Oxetanes are known to undergo homolysis through ring splitting, so that isobutene and HCHO are major products from 3,3-dimethyloxetane. 

House showed that both cis- and /w j-2,3-epoxybutane are isomerized by magnesium bromide in ether solution to butane-2-one. The cis-epoxide also gave butane-2-one in the presence of boron trifluoride, and the trans-epoxide gave both the ketone and isobutyraldehyde. A bromohydrin has been isolated also from the low-temperature isomerization of cyclohexene oxide. ... 

Besides pyridine-containing polystyrene and pol)q5ropylene resins, polybenzimidazole has been employed as support for nickel(II) acetylacetonate [94]. The nickel-loaded polymer was shown to be an efficient catalyst for the epoxidation of (S)-(—)-limonene, a-pinene, and 1-octene using isobutyraldehyde/02 as coreac-tant/oxidant. However, significant metal leaching from the support associated with a loss of activity upon recycling was reported. It was shown that the reaction is heterogeneously catalyzed, and leached metal species did not contribute to the catal)d ic activity. 

The reaction of 2-methyl-2-propenylmagnesium chloride with the allenic aldehyde 342 (from isobutyraldehyde and 2-methyl-3-butyn-2-ol) gave the precursor 343 for an internal [2 + 2] cycloaddition. After oxidation and irradiation, the bicyclo[3.2.0]heptanone 324 obtained was converted to ( )-lineatin [( )-... 

In the petrochemical industry the introduction of unsaturations in hydrocarbons is mainly obtained by dehydrogenation. This kind of reaction is less suitable for the functionalization of fine chemicals, because the high temperature necessary for the endothermic reaction can lead to the decomposition of thermally unstable compounds. An alternative reaction consists in the oxidative dehydrogenation, that can be carried out at lower temperatiu es. An example of this kind of reaction is constituted by the synthesis of methacrylic add (MAA, intermediate of methylmethacrylate production) via the oxidative dehydrogenation of isobutyric add (IBA), itself obtained from isobutyraldehyde (by-product of the oxo synthesis of nbutyraldehyde from propylene). This process constitutes one of the economically most interesting routes, alternative to the acetone-cyanohydrin process, which nowadays is the predominant process for the MAA production. 

Rare earth oxides have been studied to a lesser extent than alkaline earth oxides. However, they show characteristic selectivity in the dehydration of alcohols. Secondary alcohols form 1-olefins, whereas the same reaction over an acid catalyst produces the thermodynamically more stable 2-olefin (312). An example of an industrially important rare earth oxide catalyst is Zr02. It has several applications, including the reduction of aromatic carboxylic acids with hydrogen to aldehydes (314), the dehydration of 1-cyclohexyl ethanol to vinyl cyclohexane (315), and the production of diisobutyl ketone from isobutyraldehyde (316). The extensive use of Zr02 is mainly due to its resistance to poisoning by H2O and CO2, and its inherent catalytic activity is a result of its bifunctional acid-base properties. It contains both weakly acidic and basic sites, neither of which is susceptible to poisoning. The acid-base functionality of Zr02 is displayed in the reaction of alkylamine to nitrile (278) (Fig. 33). To form nitriles from both secondary and tertiary amines, both acid and base sites are required. 

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