Carbonylation, reviews

The use of Cp rings with pendant phosphines in CpCoL2 complexes has also been reviewed. Carbonyl complexes of this type (Cp Co(CO)2) lose CO at room temperature to afford pendant phosphane adducts (equation 46). The chelated phosphane can then be uncoordinated with ligands such as cod substitution of cod (Section 5.1.4) with alkynes allows the cobalt complex to participate in cychzation reactions (Scheme 26). 

The insertion of CO into metal-carbon o bonds has been reviewed. Carbonylation of alkyl platinum(II) complexes usually requires elevated temperatures, although at higher temperatures the reaction is reversible (equation 211). With PtMe2(dppe) insertion occurs into only one of the Pt—Me bonds. For complexes PtX(Ar)L2, carbonylation follows pseudo first-order kinetics. Rates are decreased by addition of L to a maximum value where the carbonylation rate is independent of L. The pathway involves formation of a five-coordinate intermediate PtX(Ar)(CO)L2, followed by dissociation to form PtX(Ar)(CO)L. The migratory step to yield PtX(COAr)L is unaffected by added L. This pathway is outlined in Scheme 6. ... 

Reviews Synthesis 1972, 63 Tetrahedron 1984, 40,641 Organic Reactions 1972, 19, 1. - selective 1,4-addition to a,p-unsaturated carbonyls... 

Although several experimental data concerning the functionalization of cumulenic anions are availab. a (for a review see Ref. 10) (Table I), it remains difficult to predict the compos tion of the product of a particular reaction on a rationalistic basis. Especially the outcome of reactions with carbonyl compounds seems to be... 

The subject has been reviewed (37,38). Water may be added to the feed to suppress methyl acetate formation, but is probably not when operating on an industrial scale. Water increase methanol conversion, but it is involved in the unavoidable loss of carbon monoxide. A typical methanol carbonylation flow sheet is given in Figure 2. 

Numerous diamines and aromatic dianhydrides have been investigated. WhoUy aromatic Pis have been stmctiirally modified by incorporating various functional groups, such as ether, carbonyl, sulfide, sulfone, methylene, isopropjlidene, perfluoroisopropyUdene, bipyridyls, sdoxane, methyl phosphine oxide, or various combinations of these, into the polymer backbone to achieve improved properties. The chemistry and apphcations of Pis have been described in several review articles (4). 

Simple olefins do not usually add well to ketenes except to ketoketenes and halogenated ketenes. Mild Lewis acids as well as bases often increase the rate of the cyclo addition. The cycloaddition of ketenes to acetylenes yields cyclobutenones. The cycloaddition of ketenes to aldehydes and ketones yields oxetanones. The reaction can also be base-cataly2ed if the reactant contains electron-poor carbonyl bonds. Optically active bases lead to chiral lactones (41—43). The dimerization of the ketene itself is the main competing reaction. This process precludes the parent compound ketene from many [2 + 2] cyclo additions. Intramolecular cycloaddition reactions of ketenes are known and have been reviewed (7). 

The General References and two other reviews (17,25) provide extensive descriptions of the chemistry of maleic anhydride and its derivatives. The broad industrial appHcations for this chemistry derive from the reactivity of the double bond in conjugation with the two carbonyl oxygens. 

Ca.ta.lysis, The readily accessible +1 and +3 oxidation states of rhodium make it a useful catalyst. There are several reviews of the catalytic properties of rhodium available (130—132). Rhodium-catalyzed methanol carbonylation (Monsanto process) accounted for 81% of worldwide acetic acid by 1988 (133). The Monsanto acetic acid process is carried out at 175°0 and 1.5 MPa (200 psi). Rhodium is introduced as RhCl3 but is likely reduced in a water... 

Chemica.1 Properties. Reviews of carbonyl sulfide chemistry are available (18,23,24). Carbonyl sulfide is a stable compound and can be stored under pressure ia steel cylinders as compressed gas ia equiUbrium with Hquid. At ca 600°C carbonyl sulfide disproportionates to carbon dioxide and carbon disulfide at ca 900°C it dissociates to carbon monoxide and sulfur. It bums with a blue flame to carbon dioxide and sulfur dioxide. Carbonyl sulfide reacts... 

Among the appHcations of lower valent titanium, the McMurry reaction, which involves the reductive coupling of carbonyl compounds to produce alkenes, is the most weU known. An excellent review of lower valent titanium reactions is available (195). Titanium(II)-based technology is less well known. A titanium(II)-based complex has been used to mediate a stetio- and regio-specific reduction of isolated conjugated triple bonds to the corresponding polyenes (196). 

The use of metal carbonyls in organic synthesis has been thoroughly reviewed (159—169). 

In addition they may contain ether, amide, carbonyl, sulfone, or other functional groups. References 28 and 29 provide excellent reviews of polyimide chemistry. 

Interesting structures can be formed by combinations of ring and side-chain substituents in special relative orientations. As indicated above, structures (28) contain the elements of azomethine or carbonyl ylides, which are 1,3-dipoles. Charge-separated species formed by attachment of an anionic group to an azonia-nitrogen also are 1,3-dipoles pyridine 1-oxide (32) is perhaps the simplest example of these the ylide (33) is another. More complex combinations lead to 1,4-dipoles , for instance the pyrimidine derivative (34), and the cross-conjugated ylide (35). Compounds of this type have been reviewed by Ramsden (80AHCl26)l). 

Electron deficient carbon-carbon double bonds are resistant to attack by the electrophilic reagents of Section 5.05.4.2.2(t), and are usually converted to oxiranes by nucleophilic oxidants. The most widely used of these is the hydroperoxide ion (Scheme 79). Since epoxidation by hydroperoxide ion proceeds through an intermediate ct-carbonyl anion, the reaction of acyclic alkenes is not necessarily stereospecific (Scheme 80) (unlike the case of epoxidation with electrophilic agents (Section 5.05.4.2.2(f)) the stereochemical aspects of this and other epoxidations are reviewed at length in (B-73MI50500)). 

The methods of preparation of ferrocene have been reviewed by Pauson and by Fischer. Ferrocene has been made by the reaction of ferric chloride with cyclopentadienylmagnesium bromide, by the direct thermal reaction of cyclopentadiene with iron metal, by the direct interaction of cyclopentadiene with iron carbonyl, by the reaction of ferrous chloride with cyclopentadiene in the presence of organic bases such as diethyl-amine, by the reaction of ferrous chloride with sodium cyclo-[lentadienide in liquid ammonia, and from cyclopentadiene and... 

The double bond migration in steroid hydrocarbons catalyzed by acids or noble metals (see, for example, ref. 185) will not be discussed here. A general review of nonsteroid olefin isomerization has recently been published. Iron carbonyl has been used to isomerize steroidal dienes. 

Many fluorinations by electropositive fluorine reagents produce a-fluoro carbonyl compounds as the final result An extensive review exists on the preparation of a-fiuorocarbonyl compounds [101 Also, electropositive reagents are used widely in the preparation of F-labeled radioactive materials required in positron etmssion tomography for biomedical research Excellent reviews are available on fluonne-18 labeling [//, 72]. 

The use of various amine adducts of carbonyl compounds as a method of carbonyl protection has been reviewed." ... 

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