【正文】 l ways. ? Replacement nomenclature: relating the cyclic ether to the corresponding hydrocarbon ring system and use the prefix oxa to indicate that an oxygen atom replaces a CH2 group. ? Oxirane: a cyclic threemembered ether (epoxide). ? Oxetane: a cyclic fourmembered ether. ? Common names: given in parentheses. Oxacyclopropane or oxirane (ethylene oxide) O O OOO1,4Dioxacyclohexane (1,4dioxane) Oxacyclobutane or oxetane Oxacyclopentane (tertahydrofuran) Physical Properties of Alcohols ? Alcohols have much higher . than parable ethers or hydrocarbons. Hbond OH 3 CHH OC H 3OC H 3H? Methanol, ethanol, both propanols, and tertbutyl alcohol are pletely miscible with water. ? 95%ethanol and 5%water ? azeotrope(共沸物 ,176。 C) ? The solubility of alcohols in water gradually decreases as the hydrocarbon portion of the molecule lengthens. Physical Properties Ethers ? Ethers have similar boiling points that are parable with those of hydrocarbons of the same molecular weight. The . of diethyl ether (MW = 74) is 。 limited usefulness(rearrangements ) ? OxymercurationDemercuration:Markovnikov addition of H– and –OH ? HydroborationOxidation: antiMarkovnikov but syn addition of H– and –OH Alcohols from Alkenes through OxymercurationDemercuration Complete within 20 s to 10 min at rt or below Step 1: Oxymercuration（ 羥汞化 ） C C H 2 O T H F C CH gO H O C C H 3H g O C C H 3OC H 3 C O HO+ + +2 OStep 2: Demercuration（ 脫汞 ） O H ? + N a B H 4 C CO H H+ H g + C H 3 C O ?O+C CH gO H O C C H 3Oless than an hour High yields, usually greater than 90% ? Oxymercurationdemercuration is highly regioselective. CC H 3CH O C H 3CH O C H 31 M e t h y l c y c l o p e n t e n e1 M e t h y l c y c l o p e n t a n o lH g O A c HH g ( O A c ) 2T H F H 2 ON a B H 4O H ?( 6 m i n )+ H g( 2 0 s ) H H? Rearrangements of the carbon skeleton seldom occur in oxymercuration demercuration. 1 . H g ( O A c ) 2 / T H F H 2 O2 . N a B H 4 , O H ?C H 3 C C H C H 2 C H 3 C C HO HC H 3C H 3 C H 3C H 33 , 3 D i m e t h y l 1 b u t e n e 3 , 3 D i m e t h y l 2 b u t a n o l( 9 4 % )CHHHSolvomercurationdemercuration: N a B H 4 , O H ?C C C CO RH g O 2 C C F 3C CO RHA l k e n e ( A l k o x y a l k y l ) m e r c u r i c t r i f l u o r o a c e t a t eH g ( O 2 C C F 3 ) 2 / T H F R O Hs o l v o m e r c u r a t i o nE t h e rd e m e r c u r a t i o nHydroboration（ 硼氫化反應(yīng)） : ? Carried out by using the boron hydride (B2H6) called diborane. C C H B C CH BA l k e n e+h y d r o b o r a t i o nO r g a n o b o r a n eB o r o n h y d r i d eO O B H 3T H F+ 2 2D i b o r a n e T H F : B H 3+ ?B2 H 6Great care must be used in handling diborane and alkylboranes because they ignite（自燃） spontaneously in air (with a green flame). The solution of THF:BH3 is considerably less prone to spontaneous ignition but still must be used in an inert atmosphere and with care. ? The Stereochemistry of Hydroborationa syn addition Hydroboration is regioselective and is antiMarkovnikov C H 3 C H 2 C C H 21 % 9 9 %L e s s s u b s t i t u t e dC H 3C H 3 C C H C H 3C H 32 % 9 8 %L e s s s u b s t i t u t e dsteric factors BHs y n a d d i t i o n+ e n a n t i o m e rC H 3 a n t i M a r k o v n i k o vC H 3HBH? The result of hydroborationoxidation is an antiMarkovnikov addition of water to a double bond. C H 3 C H C H 2 ( C H 3 C H 2 C H 2 ) 3 B C H 3 C H 2 C H 2 O HH 2 O 2 / O H?P r o p e n e T r i p r o p y l b o r a n e P r o p y l a l c o h o lH y d r o b o r a t i o n O x i d a t i o n3 3T H F : B H 3? Acidcatalyzed hydration (or oxymercurationdemercuration) of 1hexene: ? Hydroborationoxidation of 1hexene: C H 3 C H 2 C H 2 C H 2 C H C H 2H 3 O + , H 2 OC H 3 C H 2 C H 2 C H 2 C H C H 31 H e x e n e 2 H e x a n o l O HC H 3 C H 2 C H 2 C H 2 C H C H 2 1 . T H F : B H 31 H e x e n e 1 H e x a n o l ( 9 0 % )2 . H 2 O 2 , O H ? C H 3 C H 2 C H 2 C H 2 C H 2 C H 2 O HThe Stereochemistry of Hydroboration ? The overall result is the syn addition of –H and –OH. ? Protonolysis of Organoboranes R B R H C H 3 C O