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Topic Review
Structure and Chemistry of 3(5)-Substituted Pyrazoles
Pyrazoles are known as versatile scaffolds in organic synthesis and medicinal chemistry, often used as starting materials for the preparation of more complex heterocyclic systems with relevance in the pharmaceutical field. Pyrazoles are also interesting compounds from a structural viewpoint, mainly because they exhibit tautomerism. This phenomenon may influence their reactivity, with possible impact on the synthetic strategies where pyrazoles take part, as well as on the biological activities of targets bearing a pyrazole moiety, since a change in structure translates into changes in properties. Investigations of the structure of pyrazoles that unravel the tautomeric and conformational preferences are therefore of upmost relevance. 3(5)-Aminopyrazoles are largely explored as precursors in the synthesis of condensed heterocyclic systems, namely pyrazolo[1,5-a]pyrimidines.
  • 1.8K
  • 04 Jul 2022
Topic Review
The Phosphorus Bond
The phosphorus bond in chemical systems, which is an inter- or intramolecular noncovalent interaction, occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a covalently or coordinately bonded phosphorus atom in a molecular entity and a nucleophile in another, or the same, molecular entity. It is the second member of the family of pnictogen bonds, formed by the second member of the pnictogen family of the periodic table. 
  • 1.8K
  • 07 Mar 2022
Topic Review
Furfuryl Alcohol
Furfuryl alcohol (FuOH, C4H3OCH2OH, 2-furylmethanol, 2-furancarbinol) has applications in the fabrication of foundry resins, the ingredient production of P-series fuels, in liquid alkanes and in food production. It is also a very important intermediate in fine chemical synthesis and the polymer industry, and it is used as a chemical intermediate for the synthesis of lysine, vitamin C and levulinic acid and employed as a lubricant and as a dispersing agent.
  • 1.8K
  • 10 Oct 2020
Topic Review
Amadori Rearrangement Products
Flavor is one of the most important factors in attracting consumers and maximizing food quality, and the Maillard reaction (MR) is highly-involved in flavor formation. However, Maillard reaction products have a big drawback in their relatively low stability in thermal treatment and storage. Amadori rearrangement products (ARPs), MR intermediates, can alternatively act as potential flavor additives for their better stability and fresh flavor formation ability.
  • 1.8K
  • 18 Jan 2023
Topic Review
Thiazoles and Bisthiazoles
Thiazole, a five-membered heteroaromatic ring, is an important scaffold of a large number of synthetic compounds. Its diverse pharmacological activity is reflected in many clinically approved thiazole-containing molecules, with an extensive range of biological activities, such as antibacterial, antifungal, antiviral, antiparasitic, antitumor, antiparkinsonian, and anti-inflammatory effects.
  • 1.7K
  • 29 Mar 2021
Topic Review
Principles of the Suzuki Coupling Reaction
The Suzuki coupling is a transition metal-catalyzed, cross-coupling carbon–carbon (C–C) bond forming reaction between organic boron compounds and organic halides. As an operationally simple and versatilely applicable procedure, the Suzuki coupling reaction has found immense applications in drug discovery and development in the pharmaceutical industry. 
  • 1.7K
  • 06 Jan 2023
Topic Review
Michael Addition of Carbonyl Compounds to α,β-Unsaturated Nitroalkenes
The proline-catalyzed asymmetric Michael addition reaction of acetaldehyde with α,β-unsaturated nitroalkenes as synthetically useful routes to β-substituted derivatives of γ-Aminobutyric acid (GABA).
  • 1.7K
  • 01 Jul 2022
Topic Review
Paan
Paan (from Sanskrit: पर्ण, romanized: parṇá, lit. leaf, cognate with English fern) is a preparation combining betel leaf with areca nut widely consumed throughout South Asia and East Asia (mainly Taiwan). It is chewed for its stimulant effects. After chewing, it is either spat out or swallowed. Paan has many variations. Slaked lime (chuna) paste is commonly added to bind the leaves. Some preparations in the Indian subcontinent include katha paste or mukhwas to freshen the breath. Magahi paan is an expensive variety of betel which is grown in Aurangabad, Gaya and Nalanda districts of central Bihar. It is non-fibrous, sweeter, tastier and the softest of the lot. The origin and diffusion of betel chewing originates from and is closely tied to the Neolithic expansion of the Austronesian peoples. It was spread to the Indo-Pacific during prehistoric times, reaching Near Oceania at 3,400 to 3,000 BP; South India and Sri Lanka by 3,500 BP; Mainland Southeast Asia by 3,000 to 2,500 BP; Northern India by 1500 BP; and Madagascar by 600 BP. From India, it was also spread westwards to Persia and the Mediterranean. Paan (under a variety of names) is also consumed in many other Asian countries and elsewhere in the world by some Asian emigrants, with or without tobacco. It can be an addictive and stimulating formulation with adverse health effects, both with and without tobacco. The spit from chewing betel nuts, known as "buai pekpek" in Papua New Guinea, is often considered an eyesore. Because of this, many places have banned selling and chewing "buai".
  • 1.6K
  • 30 Sep 2022
Topic Review
Amino Acid
α-Amino acids find widespread applications in various areas of life and physical sciences. Their syntheses are carried out by a multitude of protocols, of which Petasis and Strecker reactions have emerged as the most straightforward and most widely used.
  • 1.6K
  • 04 Feb 2022
Topic Review
Phosphorus fire retardants for polystyrene
Polystyrene, despite its high flammability, is widely used as a thermal insulation material for buildings, for food packaging, in electrical and automotive industries, etc. A number of modification routes have been explored to improve the fire retardance and boost the thermal stability of commercially important styrene-based polymeric products. The earlier strategies mostly involved the use of halogenated fire retardants. Nowadays, these compounds are considered to be persistent pollutants that are hazardous to public and environmental health. Many well-known halogen-based fire retardants, regardless of their chemical structures and modes of action, have been withdrawn from built environments in the European Union, USA, and Canada. This had triggered a growing research interest in, and an industrial demand for, halogen-free alternatives, which not only will reduce the flammability but also address toxicity and bioaccumulation issues. Among the possible options, phosphorus-containing compounds have received greater attention due to their excellent fire-retarding efficiencies and environmentally friendly attributes. Numerous reports were also published on reactive and additive modifications of polystyrene in different forms, particularly in the last decade; hence, the current article aims to provide a critical review of these publications. The authors mainly intend to focus on the chemistries of phosphorous compounds, with the P atom being in different chemical environments, used either as reactive, or additive, fire retardants in styrene-based materials. The chemical pathways and possible mechanisms behind the fire retardance are discussed in this review.
  • 1.5K
  • 26 Aug 2020
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