有機合成氧化ppt課件-wenkub
2023-05-19 23:55:21 本頁面
【正文】 H 2 O 2H C O O HO HO H氧化烯烴 ? 無質(zhì)子介質(zhì)中得到環(huán)氧烷 P h C H = C H P h C H 3 C O O O HC H 2 C l 2P hOP hC H 3C H 3OC H 3C H 3C H 3 C O 3 HC H C l 3B、羰基酯化 BaeyerVilliger反應(yīng) ? 反應(yīng)式： ? 歷程： R ′ COR R C O 3 H R ′ COO RR ′ CORR C O 3 HR ′ C O RR ′ CO HRO O CORH+R C O OR ′ CO HRO+O HH+R ′ CORO烷基重排中與親核性大小有關(guān) ? 親核性越大重排也就越容易發(fā)生。 ? 酸性介質(zhì)中：側(cè)鏈氧化為酸 ? 中性介質(zhì)中：可使側(cè)鏈保留碳數(shù)氧化 ? 弱酸性介質(zhì)：不是將側(cè)鏈氧化而是氧化得到醌。 五、含鹵氧化劑 ? 常用的含鹵氧化劑： NaOCl、 HIOFeCl NBS、 NBA、 NCA ? NaOCl ? 氧化能力強，選擇性差、與 HNO3氧化能力差不多。 O HOOO HO H O HF e C l 3 / C H 3 O H N溴代丁二酰亞胺類 ? 是一類選擇性較強的氧化劑，并且選擇性與溶劑的關(guān)。 Oxidation with chronium (VI) Chromium trioxide in acetone: Jone’s Oxidation Acetone as a cosolvent Chromium trioxide Dilute sulfuric acid Example Chromium trioxidepyridine: Sarret oxidation Useful for the general oxidation of primary and secondary alcohols. Alkene, ketals and sulfide are oxidized much slower than alcohols. Drawback: Isolation of product from the pyridine solution is very difficult. Collins oxidation A modification of Sarret oxidation: the chromium trioxide – pyridine plex is first removed from the pyridine solution and added to dichloromethane. Advantages: facilitate isolation。 hindered alcohols show a reduced activity. Fetizon’s Regent Fetizon found that reaction of primary alcohol give excellent yields of the corresponding aldehyde when silver carvonate is condensed on Celite. Silver (I) oxide Selective oxidation of aldehydes to carboxylic acids. Example Silver (II) oxide Silver (II) oxide can convert aldehyde or alcohols to carboxylic acids. The isomerization of conjugated double bond is avoided. Other oxidation regents DessMartin periodinane oxid
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