Carbonylations palladium chloride

With a palladium chloride catalyst, butenediol is carbonylated by carbon monoxide, giving 3-hexenedioic acid [4436-74-2] C HgO (94). 

With palladium chloride catalyst, carbon monoxide, and an alcohol the labile hydroxyl is alkylated during carbonylation (199). 

Anhydrides are reduced with relative ease. McAlees and McCrindle 20) established the following increasing order of difficulty for various carbonyls acid chlorides > aldehydes, ketones > anhydrides > esters > carboxylic acids > amides. Reduction may proceed by 1,2-addilion of hydrogen or by cleavage of an oxygen-carbonyl bond. If 1,2-addition to the carbonyl occurs, as in the presence of strong protic acids over palladium, 1,1-diesters are formed by acylation 26). 

Palladium catalysts, 10 42 14 49 16 250 Palladium-catalyzed carbonylation, 13 656 Palladium chloride/copper chloride, supported catalyst, 5 329 Palladium compounds, 19 650-654 synthesis of, 19 652 uses for, 19 653-654 Palladium films, 19 654 Palladium membranes, 15 813 Palladium monoxide, 19 651 Palladium oxide, 19 601... 

The oxidation of olefins to carbonyl compounds by palladium (II) ion can be regarded as an addition of a palladium hydroxide group to the olefin followed by a hydrogen shift. Kinetic evidence suggests the following mechanism for the oxidation of ethylene by palladium chloride in aqueous solution containing excess chloride ion 21, 49, 99). 

Carboxylation of dienes and trienes, which takes place in a stepwise fashion, affords mono- or dicarboxylated products.146 Cobalt carbonyl,147 palladium chloride,148 149 and palladium complexes150 were used. 1,4 Addition to 1,3-butadiene gives the corresponding unsaturated tram ester (methyl trans-3-pentenoate) in the presence of [Co(CO)4]2 and a pyridine base.147 The second carboxylation step requires higher temperature than the first one to yield dimethyl adipate. In a direct synthesis (110°C, 500 atm, then 200°C, 530 atm) 51% selectivity was achieved.147... 

In the case of experiments performed under the conditions of run 6, but in the presence of 1 ml of methanol, 1.6 equivalent of dimethyl carbonate was obtained according to GC analysis. No dimethyl carbonate was observed in the absence of hydrogen chloride. Therefore, in the early stage of the carbonylation of 3, Pd/C is partly oxidized to palladium chloride (eqn. 2). This compound reacts in turn with CO and MeOH to give, according to one of the routes described in Scheme 2, dimethyl carbonate and a zerovalent palladium complex (noted [Pd]). 

When either an alcohol or an amine function is present in the alkene, the possibility for lactone or lactam formation exists. Cobalt or rhodium catalysts convert 2,2-dimethyl-3-buten-l-ol to 2,3,3-trimethyl- y-butyrolactone, with minor amounts of the 8-lactone being formed (equation 51).2 In this case, isomerization of the double bond is not possible. The reaction of allyl alcohols catalyzed by cobalt or rhodium is carried out under reaction conditions that are severe, so isomerization to propanal occurs rapidly. Running the reaction in acetonitrile provides a 60% yield of lactone, while a rhodium carbonyl catalyst in the presence of an amine gives butane-1,4-diol in 60-70% (equation 52).8 A mild method of converting allyl and homoallyl alcohols to lactones utilizes the palladium chloride/copper chloride catalyst system (Table 6).79,82 83... 

Acetic acid is manufactured by three processes acetaldehyde oxidation, //-butane oxidation, and methanol carbonylation.Ethylene is the exclusive organic raw material for making acetaldehyde, 70 percent of which is further oxidized to acetic acid or acetic anhydride. The single-stage (Wacker) process for making acetaldehyde involves cupric chloride and a small amount of palladium chloride in aqueous solution as a catalyst. 

Cyclododecene may be prepared from 1,5,9-cyclododecatriene by the catalytic reduction with Raney nickel and hydrogen diluted with nitrogen, with nickel sulfide on alumina, with cobalt, iron, or nickel in the presence of thiophene, with palladium on charcoal, with palladium chloride in the presence of water, with palladium on barium sulfate, with cobalt acetate in the presence of cobalt carbonyl, and with cobalt carbonyl and tri- -butyl phosphine. It may also be obtained from the triene by reduction with lithium and ethylamine, by disproportionation, by epoxidation followed by isomerization to a ketone and WoliT-Kishner reduction, and from cyclododecanone by the reaction of its hydrazonc with sodium hydride. ... 

The oxidation of olefins to carbonyl compounds by means of palladium chloride catalysts (and involving intermediate organopalladium compounds) 22, 225, 226),... 

Palladium chloride and metallic palladium are useful for carbonylating olefinic and acetylenic compounds. Further, palladium is active for decarbonylation of aldehydes and acyl halides. Homogeneous decarbonylation of aldehydes and acyl halides and carbonylation of alkyl halides were carried out smoothly using rhodium complexes. An acyl-rhodium complex, thought to be an intermediate in decarbonylation, was isolated by the oxidative addition of acyl halide to chlorotris(triphenylphosphine)rhodium. The mechanisms of these carbonylation and decarbonylation reactions are discussed. 

Olefins are usually carbonylated in the presence of metal carbonyls, such as nickel, cobalt, and iron carbonyls under homogeneous conditions, and the mechanism of these carbonylations has been established in several cases. On the other hand, isolation or formation of true palladium carbonyl has not been reported. Since palladium is an efficient and versatile catalyst for various types of the carbonylation mentioned above, the mechanisms of the carbonylation of olefin-palladium chloride complexes and of metallic palladium catalyzed carbonylations seem to be worth investigating. 

The following mechanism was proposed for the carbonylation of olefin-palladium chloride complex (10). The first step is coordination of carbon monoxide to the complex. Insertion of the coordinated olefin into the palladium-chlorine bond then forms a -chloroalkylpalladium complex (IV). This complex undergoes carbon monoxide insertion to form an acylpalladium complex (V), as has been assumed for many metal carbonyl-catalyzed carbonylation reactions. The final step is formation of a )8-chloroacyl chloride and zero-valent palladium by combination of the acyl group with the coordinated chlorine. 

In combination with the incremental advances concerning reaction conditions in recent years, especially for low-pressure carbonylations, there is a trend toward increasing use of this chemistry to synthesize advanced building blocks. In this respect carboxylation of alkenes with an appropriate alcohol or amine function leads to the formation of lactones or lactams. Thus, cobalt, rhodium, or palladium chloride/copper chloride catalysts convert allyl and homoallyl alcohols or amines to the corresponding butyrolactones or butyrolactams, respectively [15]. 

The carbonylation of benzyl halides in t-BuOH, catalyzed by Pd(PPh3)2Cl2 and Et3N CH2PhCr, is a mild, efficient, one-pot route to /-butyl esters of arylacetic acids [131]. Similar reactions using benzyl halides, ethanol, CO, Bu4N I", and polymer-bound palladium chloride produce ethyl arylacetates [132]. 

Alkyne cyclotrimerization occurs at various homogeneous and heterogeneous transition metal and Ziegler-type catalysts [7], Substituted benzenes have been prepared in the presence of iron, cobalt, and nickel carbonyls [8] as well as trialkyl- and triarylchromium compounds [9]. Bis(acrylonitrile)nickel [10] and bis(benzonitrile)palladium chloride [11] catalyze the cyclotrimerization of tolane to hexaphenylbenzene. NiCl2 reduced by NaBH4 has been utilized for the trimer-ization of 3-hexyne to hexaethylbenzene [12]. Ta2Cl6(tetrahydrothiophene)3 and Nb2Cl6(tetrahydrothiophene)3 as well as 7 -Ind-, and 77 -Ru-rhodium... 

This information leads to the conclusions that palladium chloride was reduced in the course of soaking, probably by the oxidizable radicals on the surface of the charcoal, that the palladium fine particles produced play the role of dissociating the adsorbed hydrogen, and that the hydrogen atom produced might migrate to the charcoal surface and react with the reactive radicals such as carbonyl on the charcoal surface. 

Lithium acetylide-Ethylenediamine. Sodium acetylide. Sodium bistrimethylsilylaraide. Carbonylation of primary amines Palladium chloride. 

Surprisingly, palladium(II) salts supported on NaY zeolite produce DMC, even without halogens. The preferred support seems to be active carbon compared to zeolites because of higher DMC selectivities based on both MN and carbon monoxide, >95% in the case of active carbon and 80-90% in the case of zeolites. Palladium chloride/copper chloride on active carbon is likely used as a catalytic system in the industrial process. Because the carbonylation of MN to DMC occurs without water coproduction, the use of palladium salts as catalysts does not adversely affect selectivity. In the carbonylation reactor outlet some amount of methyl-chloroformate is present, as expected because it is known that palladium(II) chloride supported on alumina or silica catalyzes the reaction between MN, CO, and HCl to give methylchloroformate. " The presence of halide ions in the catalytic system and the methylchloroformate generation likely raise some corrosiveness issues. 

Carbonylation of various unsaturated compounds in the presence of palladium chloride is described by Tsuji el al.4 s Since olefins form complexes with palladium chloride, these apparently are involved, but generally have not been prepared directly. In the case of simple olefins the general reaction is considered to be ... 

Yields are 5-40%. Study of allylic compounds5 and of butadiene6 has led to the following formulation of the complex of butadiene with palladium chloride and the two products obtained on carbonylation ... 

Cobalt and Ni catalyze the carbonyiation of strained cyclic esters such as /3-propiolactone and butyrolactone . Palladium chloride carbonylates esters of allyl alcohol to 3-butenoic anhydrides at 100° and 9.6 MPa. ... 

In general for carbonylations, palladium as catalyst metal is preferable to nickel with respect of catalyst efficiency. Thus, Okano, Kiji, and co-workers described some other efficient palladium-catalyzed carbonylations of allyl chloride and substituted allyl halides (Eqs. 5-10). In greater detail, the water-soluble palladium complex PdCl2[Ph2P(w-C6H4S03Na)]2 has been used in a two-phase system (e.g., aqueous NaOH/benzene medium) at atmospheric carbon monoxide pressure, giving 3-butenoic acids [20], In the carbonylation of allyl chloride a mixture of 2-bute-noic acid, which was formed by base-catalyzed isomerization, and 3-butenoic acid was obtained in up to 90% yield (TON = 135), albeit at moderate selectivity (24 76). Clearly, the isomerization depends on the concentration of the base and was therefore suppressed by a method of continuous addition to the aqueous medium. 

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