42,772 articles
Cyclic vector
A cyclic vector for a linear operator A on a vector space V is a vector whose repeated images under A span the whole space.
Cyclic voltammetry
Cyclic voltammetry (CV) is an electrochemical technique that sweeps an electrode's potential between two limits and back while recording current, revealing redox potentials and electron-transfer mechanisms.
Cyclo[18]carbon
Cyclo[18]carbon (C₁₈) is a molecular carbon allotrope, a ring of 18 carbon atoms with alternating single and triple bonds, first synthesized and imaged atom by atom in 2019 by Oxford and IBM Research–Zürich.
Cycloaddition
Cycloaddition, or cyclo-addition reaction, is a pericyclic reaction in which two or more unsaturated molecules combine to form a cyclic adduct, exemplified by the Diels-Alder reaction and governed by orbital symmetry rules.
Cycloaddition in synthesis and materials
Cycloaddition in synthesis and materials covers applications of cycloaddition reactions in total synthesis, polymer and materials chemistry, and industry, from Diels–Alder crosslinks to tetrazine ligation and flow scale-up.
Cycloalkane
A cycloalkane, or naphthene, is a saturated hydrocarbon whose carbon atoms form a closed ring; simple members have the formula CnH2n and include cyclohexane and cyclobutane.
Cycloalkyne
A cycloalkyne is a cyclic hydrocarbon with a carbon–carbon triple bond in its ring; the resulting strain makes small rings highly reactive and underlies click chemistry.
Cyclobutadiene
Cyclobutadiene is a four-membered cyclic hydrocarbon, C₄H₄, with 4 π electrons and a rectangular structure, the standard example of an antiaromatic molecule and too reactive to isolate.
Cyclodecapentaene
Cyclodecapentaene, also called [10]annulene, is a C₁₀H₁₀ hydrocarbon with a ten-membered ring of five alternating double bonds that is not aromatic despite Hückel's rule predicting it.
Cyclodextrin
Cyclodextrins are cyclic oligosaccharides produced from starch by enzymes, whose hydrophobic central cavity forms inclusion complexes with hydrophobic molecules, making them widely used pharmaceutical excipients and food additives.
Cyclohexane
Cyclohexane, also known as benzene hexahydride, is a colorless, highly flammable cyclic hydrocarbon (C₆H₁₂) that occurs in petroleum and is the main raw material for nylon intermediates such as adipic acid.
Cyclohexane conformation
Cyclohexane conformation is the set of three-dimensional shapes cyclohexane can adopt, most importantly the strain-free chair, with boat, twist-boat, and half-chair forms interconverted by rapid ring flipping.
Cyclohexanecarboxylic acid
Cyclohexanecarboxylic acid, also called hexahydrobenzoic acid, is a monocarboxylic acid on a cyclohexane ring, made from benzoic acid and used as an intermediate in nylon-6 and in the drug praziquantel.
Cyclohexanedione
Cyclohexanedione is any of three isomers of formula C6H8O2 consisting of a cyclohexane ring bearing two ketone groups, at positions 1,2 (an alpha-diketone), 1,3 (dihydroresorcinol, a versatile synthetic building block), or 1,4 (a precursor to hydroquinone).
Cyclohexanol
Cyclohexanol is a saturated six-membered-ring alcohol boiling at 161 °C, produced mainly as half of KA oil, the feedstock for nylon precursors adipic acid and caprolactam.
Cyclohexanone
Cyclohexanone, also known as Anone or pimelic ketone, is a colorless cyclic ketone with a peppermint-like odor that serves mainly as the industrial precursor to the nylon intermediates adipic acid and caprolactam.
Cyclohexanone oxime
Cyclohexanone oxime is the oxime of cyclohexanone, a white crystalline solid made by reacting cyclohexanone with hydroxylamine; it rearranges to caprolactam, the monomer of Nylon 6.
Cyclohexene
Cyclohexene (tetrahydrobenzene) is a cyclic hydrocarbon, C₆H₁₀, with a six-membered ring and one double bond; a colorless liquid, it is used chiefly as a chemical intermediate.
Cyclohexene oxide
Cyclohexene oxide, also called 1,2-epoxycyclohexane, is a cyclic epoxide, a colorless liquid with a strong odor used to make epoxy resins and the carbon dioxide-derived polymer poly(cyclohexene carbonate).
Cyclohexylamine
Cyclohexylamine (CHA, also called cyclohexanamine or hexahydroaniline) is a primary aliphatic amine, a colorless liquid made from aniline and used in boiler water treatment, rubber accelerators, and cyclamate.
Cycloid
A cycloid is the curve traced by a point on the circumference of a circle rolling along a straight line, with cusps at each touch.
Cyclone
A cyclone is a rotating low-pressure weather system with winds circling a low-pressure center, spinning anticlockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
Cyclone Aila
Cyclone Aila was a severe cyclonic storm that struck the West Bengal coast of India and south-western Bangladesh in May 2009, killing about 300 people and affecting millions.
Cyclone Alfred
Severe Tropical Cyclone Alfred was a 2025 Coral Sea cyclone that struck southeast Queensland and northern New South Wales, causing about $1.36 billion in damage and one death.
Cyclone Amphan
Cyclone Amphan (Thai: อัมพาน) was a powerful tropical cyclone that hit West Bengal, India, and Bangladesh in May 2020, causing about $14 billion in losses.
Cyclone Chido
Cyclone Chido was an intense tropical cyclone of the 2024–2025 season that struck Mayotte on 14 December 2024 with gusts over 220 km/h, then hit Mozambique.
Cyclone Ditwah
Cyclone Ditwah, officially Cyclonic Storm Ditwah, was a tropical cyclone that struck Sri Lanka in late November 2025, causing the country's deadliest cyclone disaster since 2004.
Cyclone Eline
Cyclone Eline, first named Severe Tropical Cyclone Leon, was a long-lived February 2000 cyclone that crossed the Indian Ocean, struck Madagascar and Mozambique, and contributed to devastating floods.
Cyclone Eloise
Tropical Cyclone Eloise was a tropical cyclone of the 2020–21 South-West Indian Ocean season that struck near Beira, Mozambique, in January 2021, killing at least 15 people.
Cyclone Fani
Cyclone Fani was an extremely severe cyclonic storm that struck Puri, Odisha, on 3 May 2019, prompting the evacuation of over 1.4 million people in Odisha.