Structure and nomenclature of ethers

Introduction to Ethers Nomenclature of Ethers Structure and Properties of Ethers Crown Ethers Preparation of Ethers Reactions of Ethers Nomenclature of Epoxides Preparation of Epoxides Enantioselective Epoxidation Ring-Opening Reactions of Epoxides Thiols and Sulfides... 

Nomenclature of Ethers, Epoxides, and Sulfides 650 Structure and Bonding in Ethers and Epoxides 652 Physical Properties of Ethers 652... 

Ethers are named m substitutive lUPAC nomenclature as alkoxy derivatives of alkanes Functional class lUPAC names of ethers are derived by listing the two alkyl groups m the general structure ROR m alphabetical order as separate words and then adding the word ether at the end When both alkyl groups are the same the prefix di precedes the name of the alkyl group... 

We begin by bringing you up to speed on mechanisms and reminding you how to push electrons around with those curved arrows. We jog your memory with a discussion of substitution and elimination reactions and their mechanisms, in addition to free radical reactions. Next you review the structure, nomenclature, synthesis, and reactions of alcohols and ethers, and then you get to tackle conjugated unsaturated systems. Finally, we remind you of spectroscopic techniques, from the IR fingerprints to NMR shifts. The review in this part moves at a pretty fast pace, but we re sure you can keep up. 

An additional nuance in the nomenclature of these compounds concerns their complexes. The open-chained compounds are often referred to as podands and their complexes as podates. The cyclic ethers may also be called coronands and their complexes are therefore coronates. Complexed cryptands are cryptates. The even more complicated structures known as spherands, cavitands, or carcerands are called spherates, cavitates, or carcerates, respectively, when complexed. The combination of a macrocycle (crown ether or coro-nand) and a sidechain (podand) is typically called a lariat ether. 

Node M, Hon H, Fujita E (1976) Demethylation of aliphatic methyl ethers with a thiol and boron trifluonde J Chem Soc Perkin Trans I 2237-2240 Sarkanen KV, Ludwig CH (1971) Definition and nomenclature In Sarkanen KV, Ludwig CH (eds) Lignins Occurrence, formation, structure and reactions Wiley-Interscience, New York, 1-17... 

In fact, the conformation of pyranoses is dominated by two effects, not present in the cyclohexane, which appear at positions 2 and 6 of the oxane. One of them is characteristic of hexopyranoses and I propose that we call this the coplanar effect in order not to imply a particularly restrictive structure by using the name of an effect already present in methoxyethane. The other effect, present in all pyranoses, is referred to as anomeric. This name, taken from the nomenclature of sugars because it was first recognized in this family, in fact disguises its general nature since it is also present in methyl chloromethyl ether. The consequences of these effects can be modulated by cyclohexane-type interactions, but not to the point where more than a qualitative discussion is necessary. 

In this Chspter, we discuss the structure, nomenclature, physical properties, and chemical properties of ethers and compare their physical properties with those of isomeric alcohols. Then we study the preparation and chemical properties of a group of cyclic efhers called epoxides. As we shall see, fheir most important reactions involve nudeophilic substitution. This chapter continues the discussion of S l and Sj 2 reaction mechanisms begun in Chapter 9 and continued into Chapter 10. 

Scheme 11.13. A representation of a portion of the pathway of gluconeogenesis. The 6-phosphate of glucose is considered capable of hydrolysis to glucose with the appropriate hydroiyase (EC 3.1.3.9) catalyst. The anomer shown is a (because the hydroxyl on the ano-meric carbon is cis or syn to the hydroxyl at C5, Scheme 11.14). A caution concerning nomen-ciature is needed. In the acyclic form, it is clear which carbon is number six. Cyclization to the six-membered ring pyranose (oxane) (or furanose [oxolane] when the five-membered ring forms) leaves ns with a nomenclature problem since the carbon that was C-1 (the ano-meric carbon) is often referred to as C-1 in both structures that involve formation of bonds to that carbon as well as in reactions that may occur at that carbon. However, it will be recalled (Chapter 5) that the nomenclature of cyclic ethers (and other heterocycles) generally requires that the heteroatom (or a heteroatom if more than one is present) receive the lowest number. So, the lUPAC and the lUBMB numbering system is used for archiving purposes, while the trivial nomenclature is commonly used in the literature. Both systems will be found here as appropriate.

Polybrominated diphenyl ethers (PBDEs, 12-133) are compounds structurally similar to polychlorinated biphenyls (PCBs). The numbering of209 individual PBDE congeners is analogous to the lUPAC nomenclature used for numbering PCBs (Figure 12.46). The basic skeleton is diphenyl ether with a different number and location of bromine atoms. 209 possible congeners can be derived, which... 

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