rings, generally which contain a double bound or other functional group "handle" to facilitate chemistry; these are termed ring-opening reactions. Examples include: ring opening metathesis, which can also be used to accomplish a specific type of polymerization. Ring expansion and ring contraction reactions Ring expansion and contraction reactions are common in organic synthesis, and are frequently encountered in pericyclic reactions. Ring expansions and contractions can involve the insertion of a functional group such as the case with Baeyer–Villiger oxidation of cyclic ketones, rearrangements of cyclic carbocycles as seen in intramolecular Diels-Alder reactions, or collapse or rearrangement of bicyclic compounds as several examples. Examples Simple, mono-cyclic examples The following are examples of simple and aromatic carbocycles, inorganic cyclic compounds, and heterocycles: Complex and polycyclic examples The following are examples of cyclic compounds exhibiting more complex ring systems and stereochemical features: See also Effective molarity Lactone Open-chain compound References Further reading Jürgen-Hinrich Fuhrhop & Gustav Penzlin, 1986, "Organic synthesis: concepts, methods, starting materials," Weinheim, BW, DEU:VCH, , see , accessed 19 June 2015. Michael B. Smith & Jerry March, 2007, "March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure," 6th Ed., New York, NY, USA:Wiley & Sons, , see , accessed 19 June 2015. Francis A. Carey & Richard J. Sundberg, 2006, "Title Advanced Organic Chemistry: Part A: Structure and Mechanisms," 4th Edn., New York, NY, USA:Springer Science & Business Media, , see , accessed 19 June 2015. Michael B. Smith, 2011, "Organic Chemistry: An Acid—Base Approach," Boca Raton, FL, USA:CRC Press, , see , accessed 19 June 2015. [May not be most necessary material for this article, but significant content here is available online.] Jonathan Clayden, Nick Greeves & Stuart Warren, 2012, "Organic Chemistry," Oxford, Oxon, GBR:Oxford University Press, , see , accessed 19 June 2015. László Kürti & Barbara Czakó, 2005, "Strategic Applications of Named Reactions in Organic Synthesis: Background and Detailed Mechanisms, Amsterdam, NH, NLD:Elsevier Academic Press, 2005ISBN 0124297854, see , accessed 19 June 2015. External links Molecular geometry