Acylation
Acylation is a chemical reaction in which an acyl group is introduced into a compound. This process typically involves the substitution of a hydrogen atom with an acyl group, often through the use of acyl chlorides or anhydrides. Acylation is commonly used in the synthesis of organic compounds and pharmaceuticals.
4 Key excerpts on "Acylation"
eBook - ePub- J Fisher, J.R.P. Arnold, Julie Fisher, John Arnold(Authors)
- 2020(Publication Date)
- Taylor & Francis(Publisher)
...In some instances, it is necessary to activate the potential leaving group to make it a better leaving group and thus promote the substitution reaction. Substitution reactions are a feature of carboxylic acid chemistry and aromatic chemistry. Elimination reactions Elimination reactions occur with the loss of (generally) a small neutral molecule, from a larger molecule. These reactions are common with alkyl halides and alcohols, leading, in each case, to the formation of alkenes. Oxidation and reduction processes In organic systems oxidation and reduction reactions are those that involve the gain or loss of oxygen, respectively. Reduction reactions can also involve the gaining of hydrogen; equivalent to the loss of oxygen. In many instances these processes involve free radicals. Oxidation and reduction reactions are features of the chemistry of almost all organic compounds, and are of great significance in biology. Related topics (A1) The periodic table (A2) Electron confguration Addition reactions An addition reaction is said to have occurred when a molecule has combined with another, without the loss of any part (atom or groups of atoms) of either molecule. There are two general classes of addition reaction that may be considered, nucleophilic and electrophilic addition (Section I1). For either type of addition reaction to occur one or more units of unsaturation must be present in the molecule being added to. Consequently, addition reactions are only possible with, for example, alkenes, alkynes, aldehydes, and ketones...
- Sunil S Joshi, Vivek V. Ranade, Sunil S Joshi, Vivek V. Ranade(Authors)
- 2016(Publication Date)
- Elsevier(Publisher)
...Chapter 14 Carbonylations and Hydroformylations for Fine Chemicals A.A. Kelkar Chemical Engineering and Process Development Division, National Chemical Laboratory, Pune, India Abstract Carbonylation reactions (hydroformylation and carbonylation) constitute one of the most powerful tools for C" src="../Images/B9780128014578000148/glyph_sbnd.gif" alt="glyph_sbnd"/>C bond formation in organic synthesis and represent an outstanding example of the application of homogeneous catalysis on an industrial scale. Carbonylation reactions have the potential to provide clean, atom-efficient routes for the synthesis of molecules with carboxylic acid, aldehyde and amide functional groups. However, catalyst product separation is a major problem for the application of homogeneous catalysts on an industrial scale. The manufacture of ibuprofen, one of the important antiinflammatory drugs involving palladium-catalyzed carbonylation, was the path-breaking technology in pharmaceutical chemistry. A significant amount of work is being carried out on the development of selective catalysts for specialty chemical synthesis. This chapter presents recent advances in the development of new catalysts for carbonylation reactions. Various strategies developed for the heterogenization of catalysts are also presented, with an emphasis on specialty chemicals. Keywords Homogeneous catalysis; Hydroformylation; Carbonylation; Heterogenization of homogeneous catalysts 14.1 Introduction The development of environmentally benign and clean synthetic methodologies is one of the most important goals of current research in chemistry. Conventional technologies for pharmaceuticals and fine chemicals are mostly chemistry intensive, with a focus on products with desired purity and productivity. These synthetic routes also have the drawbacks of generating significant quantities of waste, with inorganic salts as by-products, and of using corrosive and toxic reagents...
eBook - ePub- Greg T. Hermanson(Author)
- 2013(Publication Date)
- Academic Press(Publisher)
...The water-insoluble carbodiimides can be used in peptide synthesis or for the synthesis of other organic compounds. Carbodiimides are used to mediate the formation of amide or phosphoramidate linkages between a carboxylate and an amine or a phosphate and an amine, respectively (Hoare and Koshland, 1966 ; Chu et al., 1986 ; Ghosh et al., 1990). Regardless of the type of carbodiimide, the reaction proceeds by the formation of an intermediate o -acylisourea that is highly reactive and short-lived in aqueous environments. The attack of an amine nucleophile on the carbonyl group of this ester results in the loss of an isourea derivative and formation of an amide bond (see Reactions 3.11 and 3.12). The major competing reaction in water is hydrolysis. 4 Hydroxyl Reactions Hydroxyl-reactive chemical compounds include not only those modification agents able to directly form a stable linkage with an –OH group, but also a broad range of reagents that are designed to temporarily activate the group for coupling with a secondary functional group. Many of the chemical methods for modifying hydroxyls originally were developed for use with chromatography supports in the coupling of affinity ligands. Some of these same chemical reactions have found application in bioconjugate techniques for crosslinking a hydroxyl-containing molecule with another substance, usually containing a nucleophile. For instance, carbohydrate-containing molecules such as polysaccharides or glycoproteins can be coupled through their sugar residues using hydroxyl-specific reactions. In addition, polymers and other organic compounds containing hydroxyls (such as PEG) may be conjugated with another molecule using these chemistries. 4.1 Epoxides and Oxiranes An epoxide or oxirane group can react with nucleophiles in a ring-opening process. The reaction can take place with primary amines, sulfhydryls, or hydroxyl groups to create secondary amine, thioether, or ether bonds, respectively...
eBook - ePub- Gopinathan Anilkumar, Salim Saranya, Gopinathan Anilkumar, Salim Saranya(Authors)
- 2020(Publication Date)
- Wiley-VCH(Publisher)
...12 Cu-Catalyzed Carbonylation Reactions Parameswaran Sasikumar 1, Thoppe S. Priyadarshini 1, Sanjay Varma 1, Ganesh C. Nandi 2, and Kokkuvayil V. Radhakrishnan 1,3 1 CSIR-National Institute for Interdisciplinary Science and Technology, Organic Chemistry Section, Chemical Sciences and Technology Division, Thiruvananthapuram 695019, Kerala, India 2 National Institute of Technology, Department of Chemistry, Tiruchirappalli 620015, Tamil Nadu, India 3 Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India 12.1 Introduction Carbonylation reactions are part of a widely explored synthetic route for CO group containing molecules, which are extremely useful in medicine, agriculture, pharmaceuticals, and various other fields. These reactions have been adapted widely in industry because of the straightforwardness and cost-effectiveness. The versatility of carbonylation chemistry has also made it possible to insert CO in diverse kinds of substrates such as amines, halogens, hydroxyl groups, and so on. Another important feature of carbonylation chemistry is that, under proper conditions, it is possible to insert more than a single molecule of CO, like double carbonylation. The introduction of a synthetically versatile group such as CO makes this chemistry worthy of exploration; hence, there is a constant effort to improve the conditions, ease of handling, and reduce the costs involving carbonylation. Transition metals play an important role of catalysis in carbonylation chemistry. The widely used metals belong to the noble category such as Pd, Pt, Ir, etc., which are difficult to handle and require tedious conditions when carrying out a reaction in their presence. Additionally, these metals are expensive and many require expensive ligands. Consequently, these catalysts are not attractive for large-scale industrial applications...
