Chapter 16

Organic Chemistry

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ethers (R-O-R) have poor reactivity making them useful solvents epoxides however are cyclic esters which are very reactive sulfides (R-S-R) are the sulfur analogs of esters 16.1 Nomenclature of Ethers, Epoxides and Sulfides esters named by identifying the two R groups and listing them in alphabetical order followed by "ether" if groups are the same (symmetrical), use di- prefix cyclic ethers are heterocyclic KNOW SPECIFIC COMPOUNDS ON PAGE 664 rings are numbered starting at the O same naming idea hols for substances with more than one linkage each R group (between and on the ends of the O's) is named and then listed alphabetically the position of the O's is placed before the name as numbers sulfides named same way as esters but instead of "ester" add "sulfide" 16.2 Structure and Bonding in Ethers and Epoxides ethers have a larger bond angle at the oxygen than alcohols (alcohols have bigger angle than water) causes Van der Waals strain more substituted R's on the O make the angle more dramatic C-O bond distances are similar to alcohols (142pm) but shorter than C-C in alkanes (153pm) a conformation that is more staggered and more anti about the O is more stable O in a ring shrinks that bond angle drastically epoxides have significant angle strain 16.3 Physical Properties of Ethers alcohols have unusually high bp's due to hydrogen bonding ethers resemble alkanes more than alcohols in that dispersion forces are the major contributors to intermolecular attractions (despite strong dipole moments) ethers differ from alkanes in that they have a negative O that can hydrogen bond with protons of water make ethers dissolvable in water (alkanes are not) 16.4 Crown Ethers ethers can form lewis acid/base compounds with metal ions due to unshared e- pair and polar C-O bond most are weak but polyethers form much more stable complexes crown ethers cyclic compounds that have four or more O's in a ring of 12 or more atoms (including O's) named by a-Crown-b where a is the number of atoms and b is the number of oxygens crown ethers have an electron rich interior (from oxygens) and a hydrocarbon-like exterior aids in making ionic compounds dissolve in a nonpolar media ion can sit within the crown and the nonpolar exterior allows the entire crown to dissolve in the nonpolar media bring the ion along with it
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also aids in keeping ion not solvated if F- is dissolved in water or alcohol, so solvated it's not basic or nucleophilic
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Chapter 16 - ethers(R-O-R have poor reactivity making them...

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