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New Greener Developments in Direct Amidation of Carboxylic Acids
Published in Ahindra Nag, Greener Synthesis of Organic Compounds, Drugs and Natural Products, 2022
Andrea Ojeda-Porras, Diego Gamba-Sánchez
Amides, also denoted as carboxamides, are organic compounds characterized by having a carbonyl group directly bonded to a nitrogen atom. Depending on the substituents on the nitrogen, amides can be classified as primary, secondary or tertiary. When the nitrogen is only bonded to the carbon of the carbonyl group, it is a primary amide. Addition of one or two additional carbon substituents led to secondary and tertiary amides, respectively. A lactam is a cyclic amide (Figure 2.1).
Inherent FR Fibers
Published in Asim Kumar Roy Choudhury, Flame Retardants for Textile Materials, 2020
Aramid fibers consists a series of synthetic polymers in which repeating units containing large phenyl rings are linked together by amide groups. Amide groups (CO-NH) form strong bonds that are resistant to solvents and heat. Phenyl rings (or aromatic rings) are bulky six-sided groups of carbon and hydrogen atoms that prevent polymer chains from rotating and twisting around their chemical bonds. Structures 3.1 (a) and 3.1 (b) show the chemical structures of meta-aramid and para-aramid respectively.
Carboxylic Acids, Carboxylic Acid Derivatives, and Acyl Substitution Reactions
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
The fundamental structure of an amide has an amino group attached directly to a carbonyl, as shown (O=C—NR2). There are primary amides (-NH2), secondary amides (-NHR) and tertiary amides (NR2).
An expedient and rapid green chemical synthesis of N-chloroacetanilides and amides using acid chlorides under metal-free neutral conditions
Published in Green Chemistry Letters and Reviews, 2018
Amide bonds (1–5) are one of the most common linkages that are abundantly present both in natural (proteins) and in synthetic compounds (polymers). The difficulty in the controlled synthesis of amides (6–8) and their applications in different fields like polymers (9), engineering materials, detergents and lubricants led to the development of many synthetic methods (10–13), and hydration of nitriles to amides in aqueous medium (14). The physical and chemical properties of amides, such as high polarity, stability, conformational diversity and conversion of them to many other functional groups have been extensively exploited by researchers in various fields. Moreover, the amide bond formation reaction is identified as one of the top reactions presently used in the pharmaceutical industry (7, 15–17). In addition to this role, the formation of amides plays an important part in mass spectrometry (18, 19) or in cell biology (20, 21).
N-formylation of isoquinoline derivatives with CO2 and H2 over a heterogeneous Ru/ZIF-8 catalyst
Published in Journal of Experimental Nanoscience, 2022
Zhen-Hong He, Yuan-Yuan Wei, Na Li, Yong-Chang Sun, Shao-Yan Yang, Kuan Wang, Weitao Wang, Xiaoxue Ma, Zhao-Tie Liu
CO2 is a greenhouse gas, and its high concentration in the atmosphere causes many climate problems [1–3]. Conversion of CO2 into value-added chemicals represents a green way to utilize this waste C1 source and further approach net-zero carbon emission. Great efforts and significant progresses have been devoted into this issue especially in the last decade. Particularly, diversified important chemicals such as hydrocarbons, olefins, alcohols, acids, and amides have been efficiently synthesized [4–12]. Among these products, amides are one kind of important fine chemicals and pharmaceutical intermediates [13]. To efficiently synthesize amides is highly important and has caught much attentions.
Experimental investigation of plant family extracts as gas hydrate inhibitors in an offshore simulated environment
Published in Petroleum Science and Technology, 2022
Toju Odatuwa, Uche Osokogwu, Okon Efiong Okon
Gas hydrate formation depends on the pipeline conditions and fluids inside the pipeline and it can be prevented by thermal insulation, dehydration, pressure reduction and chemical injections (Khan et al. 2017). In deep offshore production, chemical injection is considered more economical and effective (Botrel 2001). These chemical inhibitors are divided into various categories such as thermodynamic hydrate inhibitors (THIs) and low dosage hydrate inhibitors (LDHIs). The LDHIs make up the kinetic hydrate inhibitors (KHIs) and anti-Agglomerants (AAs). THIs such as methanol or glycols cause a hydrate curve shifting to higher pressure and lower temperature region. The drawback is that they are toxic to aquatic lives when they leak into the marine environment. Apart from that since they require higher dosage application much space is required for their storage. KHIs are water soluble polymers. They cause gas hydrate nucleation to be delayed and crystal development to be disrupted. They are polymers with the inclination of forming hydrogen bonding with water. Examples are: poly (acryoylpyrrolidone) (PAPYD) poly (N-vinylcaprolactam) (PVCap), poly (N-vinylacetamide) (VIMA), poly (N-vinylvalerolactam) (PVVam) and poly(N-vinylpyrrolidone) (PVP), as well as examples of other amides like N-methyl-N-vinylacetamide and polyethyloxazoline (Villano, Kommedal, and Kelland 2008). Anti-Agglomerants (AAs) act as surface active molecules and they prevent hydrates from sticking together. Green hydrate inhibitors (GHIs) have evolved as a result of environmental concerns. Examples include ionic liquids (Rasoolzadeh et al. 2016), natural and biodegradable polymers (Pal, Mal, and Singh 2005) anti-freeze proteins (Perfeldt et al. 2014), amino acids (Prasad and Kiran 2018), plant extracts (Elechi et al. 2018, 2019, 2021a, 2021b; Sai, Rama, and Prasad 2020) and agro-waste based locally formulated inhibitors (Okon et al. 2018, 2022).