Propanoic acid, formation

Propanoic acid, CH3CH2COOH, is a weak monoprotic acid that is used to inhibit mould formation in bread. A student prepared a 0.10 mol/L solution of propanoic acid and found that the pH was 2.96. What is the acid dissociation constant for propanoic acid What percent of its molecules were dissociated in the solution ... 

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]. 

Electron donating a-substituents favour the non-Kolbe reaction but the radical intermediates in these anodic processes can be trapped during co-electrolysis with an alkanoic acid. Anodic decarboxylation of sugar uronic acids leads to formation of the radical which is very rapidly oxidised to a carbonium ion, stabilised by the adjacent ether group. However, in the presence of a tenfold excess of an alkanoic acid, the radical intermediate is trapped as the unsymmetrical coupling product [101]. Highly functionalised nucleotide derivatives such as 20 will couple successfully in the mixed Kolbe reaction [102], Other examples include the co-electrolysis of 3-oxa-alkanoic acids with an alkanoic acid [103] and the formation of 3-alkylindoles from indole-3-propanoic acid [104], Anodic oxidation of indole-3-propanoic acid alone gives no Kolbe dimer [105],... 

Other similar lipase/esterase resolution processes have been developed such as the use of Bacillus that esterase to produce the substituted propanoic acids that are precursors of non-steroidal anti-inflammatory drags, snch as naproxen and ibuprofen etc., and the formation of chiral amines by Celgene. Other methods start from prochiral precursors and have the advantage that enantioselective synthesis allows the production of particular isomers in yields approaching 100%, rather than the 50% yields characteristic of resolution processes. For instance Hoechst have patented the production of enantiomers using Pseudomonas fluorescens lipase to either acylate diols or hydrolyse diacetate esters. 

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). 

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). 

This rearrangement, which is important in the biochemical utilization of propanoic acid, has been shown to involve transfer of a hydrogen from the CH3— group of 25 to the —CH2R group of 24. Then rearrangement and formation of 26 occurs along with reformation of 24 ... 

Simple alkylation of the chiral chelate complex leads to formation of chiral dialkylacetic acids (Scheme 109).3S5 388 Simpler chiral enamines can also be used. The formation of chiral propanoic acids results from a resolution of racemic alkyl halides by the interaction of a chiral lithiooxazoline, which recognizes and reacts with one enantiomer at the expense of the other (Scheme 110).389 The above aspects of the asymmetric carbon—carbon bond formation from chiral oxazolines have been reviewed by Meyers.390... 

The formation of a dimerized extracted species was first reported for the extraction of copper(II) with propanoic acid (40, 41). Later, nickel and cobalt were found to be extracted as dimers (22), and a mixed copper(II) carboxylate dimer involving acetate and decanoate was reported (147). More recently, attention has been drawn to the extraction of heteropolynuclear metal carboxylates (90, 91). 

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... 

Besides water, another small molecule in the pyrolysate is CO2. This small molecule may be eliminated by various mechanisms including a hydrolysis of the amide groups with the formation of acrylic acid, followed by decarboxylation. Some small peaks In the pyrolysis of polyacrylamide are identical with those from poly(acrylic acid). Even traces of propanoic acid and propenoic acid are present in the acrylamide pyrolysate. A comparison between a time window 25.0 min. to 70 min. from the pyrogram of poly(acrylic acid) and from the pyrogram of polyacrylamide is shown in Figure 6.7.17. 

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. 

The most common error in this example is to propose propanoic acid (CH3CH2COOH) as the answer. Although propanoic acid is isomeric with ethyl formate and does possess a carbonyl, the IR of the acid would show extensive hydrogen bonding, the NMR signal for the CH2 would not be so far down-field, and the NMR peak due to the acidic hydrogen would resonate further downfield at approximately 11-12 ppm. 

One of the early examples of the use of sodium tetrachloroaluminate in intramolecular Friedel-Crafts acylation reactions involved the reaction shown in equation (49), in which P-(3-acenaphthoyl)propanoic acid was converted into perisuccinoylacenaphthene. The formation of the benzosuberanone ring system is particularly easy when electron-releasing substituents are present on the benzene ring. Under those cir-... 

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