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Micronutrients
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
Iodine (I), a metalloid (nonmetallic) element of the halogen group, is an essential micronutrient for human life. Iodine exists as iodide and complex organic iodine compounds such as thyroxin in the human body.
Monographs of Topical Drugs that Have Caused Contact Allergy/Allergic Contact Dermatitis
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
Iodine is a nonmetallic element of the halogen group that is represented by the atomic symbol I, atomic number 53, and atomic weight of 126.90. It is a nutritional element essential for growth and development and especially important in thyroid hormone synthesis. Iodine deficiency causes goitre and hypothyroidism in children and adults, and cretinism if present during fetal development. Since 1839, iodine compounds have been used as antiseptics and disinfectants. It has a broad germicidal action, being effective against bacteria, fungi, viruses, and protozoa. Iodine has traditionally been used in its tincture form, which consists of 2% iodine and 2.4% sodium iodide diluted in alcohol. Iodine preparations are currently available in aqueous solution, tincture of alcohol, aerosol, ointment, antiseptic gauze pad, foam and swab sticks (1,9). Iodine is also present in povidone-iodine (Chapter 3.270 Povidone-iodine).
Iodine that sustains electronic and information materials
Published in Tatsuo Kaiho, Iodine Made Simple, 2017
OA (office automation) equipment such as a copying machine have become indispensable in everyday life. Here, the principle of a copying machine is considered (see the diagram). When light is applied to negatively charged photoreceptors, those exposed to the light lose their charge. Toner attaches to the remaining positively charged electrons. Areas with a higher charge become darker. Why is charge lost when exposed to light? As the charge-generated material absorbs light and creates pairs of electrons (negative) and electron holes (positive). The charge-generating material transports the electron holes to the surface and binds them with the electrons. As a result, surface charge is negated. To accomplish this, a vital component of the photoreceptor is the charge (electron hole) transport material [22a]. Typical compounds are shown in the center left diagram. All have a tiphenylamine dimer (TPD) structure. The nitrogen atom has a lone pair of electrons, but these electrons tend to separate and become radical caions. Iodine, in the form of iodine compounds, is used for components in the compounds shown in the diagram. For example, TPD is synthesized from diiodobiphenyl and diphenylamine using the Ullman reaction (reaction formula) [22b].
Iodine-mediated one-pot intramolecular decarboxylation domino reaction for accessing functionalised 2-(1,3,4-oxadiazol-2-yl)anilines with carbonic anhydrase inhibitory action
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2018
Srinivas Angapelly, P. V. Sri Ramya, Rohini Sodhi, Andrea Angeli, Krishnan Rangan, Narayana Nagesh, Claudiu T. Supuran, Mohammed Arifuddin
Construction of O–heterocyclic ring systems via intramolecular C–O bond formation has become an emerging tool in drug discovery. Accordingly, many efforts have been devoted to this activity, and remarkable results have been achieved to date. Among these, the traditional intramolecular Pd-catalysed Hartwig–Buchwald1 and copper-catalysed2 Ullmann-type C–O coupling of aryl halides with hydroxyl moieties, and in an alternative approach, the direct dehydrogenative coupling occurs between C–H and O–H bonds3, leading to various functionalised compounds. In most cases, these elaborative designs implied complex catalytic systems (based on Pd(II), Cu(II), Rh(III), and Ru(III) derivatives) and multi-step processes for the preparation of diversely functionalised derivatives, such as, furan, pyrrole, pyrazole, isoquinoline, indole, benzoxazole, and carbazole ring systems4. However, oxidative decarboxylation leading to construction of C–heteroatom bonds, particularly the C–O and the C–N bonds, has received significantly less attention. In recent years, in the perspective of green chemistry, most of the organic chemists have switched to metal-free reactions to reduce the burden of toxicity. In this context, iodine and hypervalent iodine reagents have emerged as inexpensive, versatile, and environmentally more friendly reagents5. Structural features and the reactivity pattern of these iodine compounds in many aspects are similar to those of the transition metal compounds applied for such purposes. Up until now, many efforts have been made to directly functionalise C–H bonds for the construction of C–C and C–heteroatoms bonds by employing iodine or hypervalent iodine reagents6,7. Wang et al. demonstrated a facile access to various heterocycles (quinazoline, oxazole, and pyridine) through the tandem oxidative coupling reactions using iodine as catalyst and tert-butyl-hydroperoxide (TBHP) as the oxidant8. Furthermore, Ma et al. proposed the synthesis of imidazo[1,2-a]pyridines via oxidative coupling of 2-aminopyridine with 1,3-diketones in the presence of tetra-butylammonium iodide (TBAI), TBHP, and BF3·etherate9. Very recently Tang et al. reported iodine-catalysed radical oxidative annulation for the synthesis of dihydrofurans and indolisines10. Interestingly, I2 (or hypervalent iodine derivatives) also promoted the oxidative decarboxylation of amino acids and β,γ-unsaturated carboxylic acids11. Intrigued by these advances, herein we envisioned a metal-free, iodine-mediated domino strategy involving intramolecular decarboxylative coupling of isatins, and hydrazides for the synthesis of 2-(1,3,4-oxadiazol-2-yl)aniline derivatives (Scheme 1).