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Carboxylic Acids, Carboxylic Acid Derivatives, and Acyl Substitution Reactions
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
The acidic hydrogen of the OH group is strongly hydrogen bonded to the carbonyl oxygen of a second carboxyl, and hydrogen bonding is possible in protic solvents such as water or an alcohol.When compared to an alcohol of similar molecular weight, a carboxylic acid generally has a much higher boiling point. Why?
Chemical Methods
Published in Somenath Mitra, Pradyot Patnaik, Barbara B. Kebbekus, Environmental Chemical Analysis, 2018
Somenath Mitra, Pradyot Patnaik, Barbara B. Kebbekus
Compounds containing functional groups with active hydrogen atoms such as the –COOH, –OH, –NH, and –SH groups have the tendency to form intermolecular hydrogen bonds that can affect the volatility and the thermal stability of the compounds containing them. Also such substances may interact with the column-packing materials. As mentioned earlier carboxylic acids with the functional group, –COOH do not produce sharp peaks. Also they are too acidic to shorten the column life. A very strong polar column therefore may be needed for analyzing if such substance is not converted into a suitable derivative. Carboxylic acids are often esterified with alcohols using an acid catalyst such as dilute HCl or H2SO4 or BF3. Methanol or diazomethane may be used to convert such acids into their methyl esters. Such esterification reactions may also be carried out by other routes using an acid chloride or an acid anhydride. Amide derivatives may alternatively be prepared instead of esters in such analysis. Carbonyl functional group (C=O} in aldehydes and ketones may be derivatized with 2,4-dinitrophenylhydrazine or semicarbazide to produce their corresponding phenylhydrazone or semicarbazone derivatives, respectively, for their GC detection using a nitrogen–phosphorus detector in N mode or for their GC/MS analysis. Practically any organic functional group may be derivatized with an appropriate reagent for its trace analysis by chromatography, mass spectrometry, or spectrophotometry. Some other examples of derivatization reactions are given below.
Biomass Chemistry
Published in Jay J. Cheng, Biomass to Renewable Energy Processes, 2017
Aldehydes are organic compounds that contain a terminal carbonyl group in which there is at least one hydrogen atom connected to the carbonyl carbon. The general formula for aldehydes is R–(CO)–H, where R is a substituent group, which can be a hydrogen atom, aliphatic or aromatic. Ketones have two carbon atoms attached to the carbonyl carbon and have the general formula R1–(CO)–R2, where R1 and R2 can be aliphatic or aromatic groups. Carboxylic acids contain a carbonyl group bonded to a hydroxyl group and have the general formula R–COOH, where R can be an aliphatic or aromatic group. Esters contain a carbonyl group bonded to an oxygen atom and have the general formula (R1–COO–R2) where R1 can be a hydrogen atom that is part of an aliphatic or aromatic group, and R2 can be an aliphatic or aromatic group.
Evaluation of lipase from Burkholderia cepacia immobilized in alginate beads and application in the synthesis of banana flavor (isoamyl acetate)
Published in Chemical Engineering Communications, 2018
Giovana S. Padilha, Elias B. Tambourgi, Ranulfo M. Alegre
Esters are among the most important classes of organic compounds. Reactions between alcohols and carboxylic acids commonly synthesize these esters. Short-chain esters (2 to 8 carbon atoms) are important flavor and aroma components in the food, beverage, cosmetic, and pharmaceutical industries (Gubicza et al., 2001). However, the reactions of ester formation are generally slow and require the use of a suitable catalyst to become economically viable. Traditional catalytic processes involve acids and bases as reaction accelerators (Malcata et al., 1990; Morrison et al., 2011). These catalysts have gradually been replaced with enzymes, which offer some benefits to permit mild operation conditions, greater specificity, and fewer losses (Gabelman, 1994).
Reactive extraction of lactic and acetic acids from leached bed reactor leachate and process optimization by response surface methodology
Published in Environmental Technology, 2023
Debkumar Chakraborty, Sankar Ganesh Palani, Makarand M. Ghangrekar, Jonathan W.C. Wong
The carboxylic acids, such as acetic and lactic acids, have many applications in the pharmaceutical, food, and allied industries. Significant progress has been made to replace fossil fuel-based carboxylic acid production with alternative sustainable and renewable biomass, including FW [5]. During the acidogenesis of carbohydrate-rich and high solid FW in LBR, the mixed culture fermentation produces the leachate with a diverse stream of carboxylic acids, including lactic acid (LA) [6] and acetic acid (AA) [7]. The degree of leachate acidification by LA and AA is high due to their low pKa values (3.86) and (4.76), respectively, as compared to other VFAs such as butyric (4.82) and propionic (4.87) acids [8]. The LA consumption, combined with alcohol and other carboxylic acids, lowers the pH and alters the free energy change of the reactions that produce and consume VFAs by limiting the oxidation of VFAs such as propionate and butyrate, consequently limiting AA production [9,10]. Accumulated LA also causes an increase in propionate concentration, which has a negative impact on the bioconversion of other VFAs and delays acidogenesis, all of which reduces the overall bioresource recovery efficiency of LBR [6,11–13]. Hence, regulating the carboxylic acid, including VFA and LA concentrations in the LBR, ensures the smooth progression of acidogenesis and concomitant energy recovery. Lime is typically added to the fermentors to control the pH and recover LA and VFA in AD. This process produces a byproduct known as calcium sulphate (gypsum), which raises waste disposal concerns. However, the overall bioresource recovery can be improved by separating LA and other VFAs from the fermentation medium as soon as they accumulate in the LBR.
Bioleaching for Recovery of Metals from Spent Batteries – A Review
Published in Mineral Processing and Extractive Metallurgy Review, 2022
Farhad Moosakazemi, Sina Ghassa, Mohammad Jafari, Saeed Chehreh Chelgani
Organic acids, such as carboxylic acids, are biodegradable and less corrosive compared to inorganic acids (Asadi et al. 2018; Bahaloo-Horeh and Mousavi 2017). Based on their pKa values, dilute solutions of carboxylic acids have moderately acidic pH values in the range of 3–5. Organic acids are available through chemical synthesis (Karaffa, Sándor, and Fekete 2001) and as metabolites from central metabolic pathways. Fungi can grow over a wide pH range and tolerate toxic metals (Santhiya and Ting 2005).