Isobutane carbonylation

Petroleum Gases and Naphtha. Methane is the main hydrocarbon component of petroleum gases. Lesser amounts of ethane, propane, butane, isobutane, and some 0 + light hydrocarbons also exist. Other gases such as hydrogen, carbon dioxide, hydrogen sulfide, and carbonyl sulfide are also present. 

Zeolites have also been described as efficient catalysts for acylation,11 for the preparation of acetals,12 and proved to be useful for acetal hydrolysis13 or intramolecular lactonization of hydroxyalkanoic acids,14 to name a few examples of their application. A number of isomerizations and skeletal rearrangements promoted by these porous materials have also been reported. From these, we can underline two important industrial processes such as the isomerization of xylenes,2 and the Beckmann rearrangement of cyclohexanone oxime to e-caprolactam,15 which is an intermediate for polyamide manufacture. Other applications include the conversion of n-butane to isobutane,16 Fries rearrangement of phenyl esters,17 or the rearrangement of epoxides to carbonyl compounds.18... 

Carboxylic acids can also be formed by a reaction of small alkanes, carbon monoxide, and water on solid acid catalysts (93,94). By in situ C MAS NMR spectroscopy (93), the activation of propane and isobutane on acidic zeolite HZSM-5 was investigated in the presence of carbon monoxide and water. Propane was converted to isobutyric acid at 373 73 K, while isobutane was transformed into pivalic acid with a simultaneous production of hydrogen. On SZA, methyl isopropyl ketone was observed as evidence for the carbonylation of isobutane with carbon monoxide after the sample was held at 343 K for 1 h (94). When the reaction of isobutane and carbon monoxide was carried out in the presence of water, pivalic acid was identified as the main reaction product (94). These observations are rationalized by the existence of a small number of sites capable of generating carbenium ions, which can be further trapped by carbon monoxide (93). 

Olah et al.450 have recently described a new, highly efficient superelectrophilic formylation-rearrangementofisoalkanes. Branched ketones are formed in high yields and with high selectivity with no detectable branched acids (Koch products) in the presence of moderately strong superacids such as HF-BF3 or triflic acid-BF3. Carbonylation of isobutane under such conditions gives isopropyl methyl ketone in high yield [Eq. (5.164)] The transformation was interpreted with the involvement of... 

In the Koch-Haaf reaction, a superacid/CO mixture leads to carbonylation of the alkane. A variety of products were obtained, e.g. BuKTOaH, IVCHCOMe and Pr CHaCOBu, from isobutane using this product. Usually the method is only useful for alkanes containing a tertiary C—H bond, but Sommer has introduced a modification that sdlows secondary C—H bonds to be functionalized, although only with 4% conversion (equation 3S). ... 

There is no direct experimental evidence for this complex decomposition and it may well occur by several steps [107]. However, substantial yields of unsaturated carbonyl compounds are formed particularly at high pressures [78] under initial reaction conditions where cool flames propagate. For example, the cool-flame oxidation of 2-methylpentane at 525 °C and 19.7 atm in a rapid compression machine [78] yields no less than 14 unsaturated carbonyl compounds viz acrolein, methacrolein, but-l-en-3-one, pent-2-enal, pent-l-en-3-one, pent-l-en-4-one, trans-pent-2-en-4r one, 2-methylbut-l-en-3-one, 2-methylpent-l-en-3-one, 4-methylpent-l-en-3-one, 2-methylpent-l-en-4-one, 2-methylpent-2-en-4-one, 2-methyl-pent-2-enal and 4-methylpent-2-enal. Spectroscopic studies of the preflame reactions [78] have shown that the unsaturated ketones account for ca. 90 % of the absorption which, occurs at 2600 A. At lower initial temperatures and pressures acrolein and crotonaldehyde are formed from n-pentane [69, 70] and n-heptane [82], and acrolein is also formed from isobutane [68]. 

Fig. 1.1. Shapes of molecules represented by envelopes of constant electronic charge density. The envelope shown has the value of 0.001 au. The molecules are (a)-(f) the normal alkanes from methane to hexane (g) isobutane (h) neopentane (i) cyclopropane (j) cyclobutane (k) formaldehyde, H2OK) (/) acetone, (CH3)2C=0. The intersections of the zero-flux interatomic surfaces with the envelope are shown in some cases. They define the methyl, methylene, hydrogen, and carbonyl groups. The isobutane molecule (g), for example, exhibits three methyl groups topped...

Reaction of carbonyl compounds with triisobutylalane also is often not limited to reduction. Only 1 mole of isobutene is obtained with cyclohexanone and acetophenone because, following enolization of the ketone, isobutane is split off from the two last isobutyl groups 274) ... 

The proton-catalyzed hydroxyalkylation of phenolic substances with carbonyl compounds is one of the reactions in which a weak acid catalyst is required, as strong acids will lead to oligomerization. The possible reaction routes of phenol reacting with the two aldehydes studied are shown in Figure 1. Especially with formaldehyde, mono-substituted products are difficult to obtain, because of the fast consecutive dimerization when larger carbonyl compounds are applied (such as isobutanal), monomer formation might be enhanced because of steric reasons. 

Superacid DF-SbFs induces protium-deuterium exchange in isobutane [54b]. Strong acids (BF3, BFj-HjO, HF-BFj, CF3SO3H)catalyze carbonylation of alkanes including methane by carbon monoxide [54c], whereas sulfuric acid can induce carbonylation of iso- and cycloalkanes [54e,d]. In both cases, carboxylic acids are obtained. The elimination of molecular hydrogen from alkyl can occur (see a recent theoretical study of the Hz elimination from CzHs [54f]). 

NEON (liquid, refrigerated) neon, compressed (cylinder) neon gas (cylMer) neopentane, see BUTANE neopentane, see ISOBUTANE neopentanolc acid NEOPENTYL GLYCOL NICKEL CARBONYL NICKEL SULFATE nickel (II) sulfate nickel tetracarbonyl NICOTINE niobe oil p-nitranlllne... 

The aldol addition of certain non-racemic a-sulfinyl enolates to carbonyl compounds affords the corresponding adducts in up to 98% enantiomeric excess and in good chemical yields [87a,b, 88]. DiFuria has shown that the magnesium enolate derived from (-)-Trans-2-iV,Af-diethylacetamide-l,3-dithiolane-l-oxide, which is obtained in high ee using the enantioselective oxidation pioneered by himself and Modena [89], undergoes aldol-type addition with isobutanal to furnish the alcohol as a single diastereoisomer [90]. The relative stereochemistry of the... 

In a subsequent publication, Meutterties reports that under flow conditions, at 1 atm pressure and 170-180 C, Cj-Cs hydrocarbons may be detected, but now isobutane and propane are the major products (116). Hydrogen chloride is a coproduct, but no methanol or CH3CI could be detected. An iridium carbonyl chloride species was suggested as the enduring catalyst precursor, basis ir data and by comparison with the formally analogous BBr3-0s3(C0)12 system. 

The reaction is often initiated by photolysis of bromine. The hydrogen-abstraction step is rate-limiting, and the product composition is governed by the selectivity of the hydrogen abstraction. The enthalpy requirement for abstraction of hydrogen from methane, ethane (primary), propane (secondary), and isobutane (tertiary), by bromine atoms are -1-16.5, -1-10.5, -1-7.0, and -1-3.5 kcal/mol, respectively. These differences are reflected in the activation energies, and there is a substantial kinetic preference for hydrogen abstraction in the order tertiary > secondary > primary. Structural features that promote radical stability by delocalization, such as phenyl, vinyl, or carbonyl substituents, also lead to kinetic selectivity in radical brominations. 

For nonpolar fluids [32, 33] (methane, ethane, propane, n-butane, w-pentane, n-hexane, n-heptane, n-octane, argon, oxygen, nitrogen, ethylene, isobutane, cyclohexane, sulfur hexafluoride, carbon monoxide, carbonyl sulfide, n-decane, hydrogen sulfide, isopentane, neopentane, isohexane, krypton, w-nonane, toluene. 

In 2002 a process for the direct carbonylation of saturated hydrocarbons has been patented (83). The process involves contacting the saturated hydrocarbons, which contain at least one primary, secondary or tertiary carbon atom, with carbon monoxide in the presence of a strong solid acid catalyst to produce an oxygenated saturated hydrocarbon. However, the observed conversions were small. For example, 119 g of isobutane, reacted at 100° C for 12 h with carbon monoxide (68 atm) using sulfated zirconia as the catalyst, produced only 0.14 g of pivalic acid and 0.007 g of methylisopropyl ketone. 

Carbonylation of Alkanes. It has been reported that propane and isobutane undergo carbonylation on zeolite H-ZSM-5 in accordance with the following scheme (100) ... 

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