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  2. Heterocyclic compound - Wikipedia

    en.wikipedia.org/wiki/Heterocyclic_compound

    A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). [1] Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and applications of organic heterocycles .

  3. Hemiacetal - Wikipedia

    en.wikipedia.org/wiki/Hemiacetal

    In organic chemistry, a hemiacetal is a functional group the general formula R 1 R 2 C(OH)OR, where R 1, R 2 is a hydrogen atom or an organic substituent. They generally result from the nucleophilic addition of an alcohol (a compound with at least one hydroxy group ) to an aldehyde ( R−CH=O ) or a ketone ( R 2 C=O ) under acidic conditions.

  4. Category:Five-membered rings - Wikipedia

    en.wikipedia.org/wiki/Category:Five-membered_rings

    Compounds containing rings with five atoms in them. ... Thiazoles (5 C, 126 P) Thiazolidines (1 C, 25 P) Thiazolines (1 C, 10 P) Thiolanes (8 P) Thiophenes (4 C, 130 P)

  5. Category:Heterocyclic compounds with 5 rings - Wikipedia

    en.wikipedia.org/wiki/Category:Heterocyclic...

    Pages in category "Heterocyclic compounds with 5 rings" The following 108 pages are in this category, out of 108 total. This list may not reflect recent changes .

  6. Cyclic compound - Wikipedia

    en.wikipedia.org/wiki/Cyclic_compound

    A cyclic compound or ring compound is a compound in which at least some its atoms are connected to form a ring. [1] Rings vary in size from three to many tens or even hundreds of atoms. Examples of ring compounds readily include cases where: all the atoms are carbon (i.e., are carbocycles),

  7. Earth ring theory may shed light on an unexplained ancient ...

    www.aol.com/earth-may-had-saturn-ring-115417013.html

    Earth may have had a ring made up of a broken asteroid over 400 million years ago, a study finds. The Saturn-like feature could explain a climate shift at the time.

  8. Xylose - Wikipedia

    en.wikipedia.org/wiki/Xylose

    The cyclic hemiacetal isomers are more prevalent in solution and are of two types: the pyranoses, which feature six-membered C 5 O rings, and the furanoses, which feature five-membered C 4 O rings (with a pendant CH 2 OH group). Each of these rings is subject to further isomerism, depending on the relative orientation of the anomeric hydroxy group.

  9. Pyranose - Wikipedia

    en.wikipedia.org/wiki/Pyranose

    The pyranose ring is formed by the reaction of the hydroxyl group on carbon 5 (C-5) of a sugar with the aldehyde at carbon 1. This forms an intramolecular hemiacetal.If reaction is between the C-4 hydroxyl and the aldehyde, a furanose is formed instead. [1]