Methyl Propanoate Formation

In this chapter we will discuss some aspects of the carbonylation catalysis with the use of palladium catalysts. We will focus on the formation of polyketones consisting of alternating molecules of alkenes and carbon monoxide on the one hand, and esters that may form under the same conditions with the use of similar catalysts from alkenes, CO, and alcohols, on the other hand. As the potential production of polyketone and methyl propanoate obtained from ethene/CO have received a lot of industrial attention we will concentrate on these two products (for a recent monograph on this chemistry see reference [1]). The elementary reactions involved are the same formation of an initiating species, insertion reactions of CO and ethene, and a termination reaction. Multiple alternating (1 1) insertions will lead to polymers or oligomers whereas a stoichiometry of 1 1 1 for CO, ethene, and alcohol leads to an ester. 

Kolbe noted also the formation of traces of methyl acetate and butyl valerate from electrolysis of acetate and valerate respectively. Careful analysis of reaction products by Petersen (1900) identified compounds which are today formulated as being derived from carbocations formed by loss of one electron from the alkyl radical [50]. Propanoic acid gives mostly ethene while butanoic acid and 2-methyl-propanoic acid give mostly propene. Acetate and long chain alkylcarboxylates give mostly the Kolbe type dimer hydrocarbon on electrolysis of their potassium salts in concentrated solution at a platinum electrode, using high current density and low temperatures [51]. 

The names of esters consist of two words that reflect their formation from an alcohol and a carboxylic acid. According to the 1UPAC rule. Ihe alkyl or aryl group of the alcohol is cited first followed by the carboxylate group of the acid with the ending -ate replacing the -ic of the acid. For example. CHiCHiCOOCH, the methyl ester of propanoic acid, is called methyl propanoate (or methyl propionate, if the trivial name, propionic acid, is used for the carboxylic acid). 

Deprotonation by electrogenerated bases, from the probase ethyl 2-bromo-2-methyl-propanoate, of )S-bromoamides or S-bromohydroxamic esters has been used to form lactams through N-C4 bond formation [62]. 

The reactions of ethylene with CO and methanol to form methyl propanoate catalyzed by complexes of various phosphinomethylbenzenes are shown in Equation 17.37 and Table 17.3. These data show the importance of the hindered fert-butyl groups on the l,2-bis(di-ferf-butylphosphinomethyl)benzene ligand (DTBMPB) and the relative insensitivity to the substituents on the arene ring of the backbone. Reactions catalyzed by complexes of this ligand form monomeric esters with high selectivity over formation of CO/ethylene copolymers and oligomers. Furthermore, the activity for formation of the ester is a remarkable 12,000 turnovers per hour. 

Eastham GR, Tooze RP, Kilner M, Foster DF, Cole-Hamilton DJ. Deuterium labelling evidence for a hydride mechanism in the formation of methyl propanoate from carbon monoxide, ethene and methanol catalysed by a palladium complex. J. Chem. Soc., Dalton Trans. 2002 1613-1617. 

The transformation of the porphyrin intermediate 4 into a chlorin can be achieved after introduction of a C — C double bond into the 15-propanoate side chain of 4 to yield 5. The cyclization of 5 with participation of the 15-acrylic ester side chain under acidic conditions gives the chlorin 6 which is then transformed in a multistep reaction sequence into chlorophyll a. The driving force of chlorin formation from the porphyrin is believed to be the relief of steric strain at the sterically overcrowded porphyrin periphery which gives the desired trans arrangement of the propanoate side chain and the methyl group in the reduced ring. The total... 

According to Fig. 2, one of the steps in chain formation with propanoate will result in the formation of an a-methyl-P-ketoacyl moiety A, which, similarly to an acetogenin (Fig. 1), may be converted to the acid precursor D, via reduction to B and dehydration to C, followed by hydrogenation. Alternatively, after another two cycles, decarboxylation would provide an ethyl ketone like 4,6-dimethylnonan-3-one, III, a component of the pheromone bouquet of caddis flies, Potamophylax spp. [43]. 

Dimethylnonyl propanoate 196 (Scheme 22), the female produced sex pheromone of several corn root worm species, Diabrotica spp. keeps ( -configuration at the methyl branching, whereas the stereochemistry at the oxygen function may vary with species (including the formation of mixtures) [359,360]. The structure of the pheromone of the southern corn root worm D. undecim-punctata, ( )-10-methyltridecan-2-one 197, is closely related to 196 [361,362]. Compared with 196 and 197, (6R, 122 )-6,10-dimethylpentadecan-2-one 198, the sex pheromone of D. balteata shows similar structural features [363,364]. 

En route to 1 -/J-methyl carbapenem antibiotics, the reaction of 31 with Reformatsky reagents 78 has been explored it likely involves preliminary formation of the intermediate 79, which then undergoes nucleophilic addition to give 2-(4-oxoazetidin-2-yl)-propanoic acid derivatives 80 (equation 48). 

Benzoylbenzene, 458 Benzoyl Peroxide, 43 Benzyl Acetate, 458, 570, 608 Benzyl Alcohol, 458, 570, 646 Benzyl Benzoate, 458, 647 Benzyl Butyrate, 458, 647 Benzyl n-Butyrate, 458 Benzyl Cinnamate, 458, 647 Benzyl Formate, 460, 608 Benzyl Isobutyrate, 460, 608 Benzyl Isovalerate, 460, 648, (Sl)60 Benzyl 3-Methyl Butyrate, 460 Benzyl 2-Methyl Propionate, 460 Benzyl Phenylacetate, 460, 608 Benzyl Propanoate, 460 Benzyl Propionate, 648 Benzyl Salicylate, 460, 682 Bergamot Oil, Coldpressed, 44, 575 beta Cyclodextrin, (Sl)15 Beta-1,3-Glucan, (S3)15 BHA, 44 BHT, 45... 

Interestingly, the ring opening of 2-aziridinecarboxylic acid methyl ester 79 by a number of aromatic thiols under solvent-free and noncatalytic conditions resulted in the formation of bis-arylsulfanyl propanoic acid esters 82. Since only traces of the monosubstituted compound 80 were occasionally found in the crude reaction mixture, it would... 

Pyrolysis process for poly(2-hydroxyethyl methacrylate) occurs similarly to that for other methacrylic acid esters. The formation of 2-methyl-2-propenoic acid 2-hydroxyethyl ester, the monomer, shows that unzipping is a significant part of the process. Some other compounds in the pyrolysate also are generated from the polymer cleavage, such compounds including 2-methyl-2-propenoic acid ethenyl ester, propanoic acid, 2-methyl-2-propenoic acid, ethanol, etc. On the other hand, some compounds are not expected in the pyrolysate and they can be impurities or additives. Examples of such compounds are the hydrocarbons (undecene, dodecane, 1-dodecene, etc.), the esters of ethylene diol and the free 1,2-ethandiol, etc. The initiator AIBN and its decomposition products 2-methyl-2-propenenitrile and 2-methylpropanenitrile identified in the pyrolysate show that the polymer was obtained using AIBN as initiator. 

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