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- On-water reactions are a group of organic reactions that take place as an emulsion in water and have an unusual reaction rate acceleration compared with (i) the same reaction in an organic solvent, or (ii) the corresponding dry media reaction. This effect has been known for many years but in 2005 researchers in the group of K. Barry Sharpless published a systematic study into this phenomenon. The rate acceleration is found in certain Claisen rearrangements. In one typical example of this reaction at room temperature the chemical yield was found to be 100% on water after 120 h compared with 16% for the same reaction in toluene and 73% in the neat reaction. Enhanced reactivity is also found in cycloadditions. The reaction of quadricyclane with DEAD is a 2σ + 2σ + 2π cycloaddition that on water takes place within 10 minutes at room temperature with 82% yield. The same reaction in toluene takes 24 hours at 80 °C with 70% yield. An emulsion reaction in fluorinated cyclohexane takes 36 hours and the neat reaction takes even longer (48 hours). Other reactions with apolar reactants such as Ene reactions and Diels–Alder reactions also exhibit rate accelerations. An explanation is not available but it involves hydrogen bonding and the presence of a small amount of dissolved solute. This reaction type is of interest to green chemistry because it greatly reduces the usage of organic solvents, reaction product isolation is relatively easy, and it increases the yields and chemical purity with little extra expenditure, if not less. (en)
- 水上反应是一组以乳浊液形式在水中发生的有机反应，与有机溶剂中的相同反应或与相应的固相反应相比，反应速率表现出不寻常的加快。这种效应已为人所知多年，但在2005年，巴里·夏普莱斯小组的研究人员才对这一现象进行了系统研究。 在某些克莱森重排反应中发现了速率加速。在室温下该反应的一个典型例子中，发现120小时后水上的化学产率为100%，而甲苯中相同反应的化学产率为16%，纯反应的化学产率为73%。 在环加成反应中也发现了反应性的增强。与DEAD的反应是2σ+2σ+2π环加成反应，在室温下在水上反应10分钟，产率为82％。甲苯中的相同反应在80℃下进行24小时，产率为70％。氟化环己烷中的乳液反应需要36小时，而纯反应需要更长时间（48小时）。 与非极性反应物的其他反应，如烯反应和狄尔斯–阿尔德反应也表现出速率加速。无法解释这种现象，但它涉及氢键和少量溶解的溶质的存在。这种反应类型对于绿色化学是有意义的，因为它大大减少了有机溶剂的使用，反应产物的分离相对容易，而且增加了产率和化学纯度，几乎没有额外的支出。 (zh)
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- 水上反应是一组以乳浊液形式在水中发生的有机反应，与有机溶剂中的相同反应或与相应的固相反应相比，反应速率表现出不寻常的加快。这种效应已为人所知多年，但在2005年，巴里·夏普莱斯小组的研究人员才对这一现象进行了系统研究。 在某些克莱森重排反应中发现了速率加速。在室温下该反应的一个典型例子中，发现120小时后水上的化学产率为100%，而甲苯中相同反应的化学产率为16%，纯反应的化学产率为73%。 在环加成反应中也发现了反应性的增强。与DEAD的反应是2σ+2σ+2π环加成反应，在室温下在水上反应10分钟，产率为82％。甲苯中的相同反应在80℃下进行24小时，产率为70％。氟化环己烷中的乳液反应需要36小时，而纯反应需要更长时间（48小时）。 与非极性反应物的其他反应，如烯反应和狄尔斯–阿尔德反应也表现出速率加速。无法解释这种现象，但它涉及氢键和少量溶解的溶质的存在。这种反应类型对于绿色化学是有意义的，因为它大大减少了有机溶剂的使用，反应产物的分离相对容易，而且增加了产率和化学纯度，几乎没有额外的支出。 (zh)
- On-water reactions are a group of organic reactions that take place as an emulsion in water and have an unusual reaction rate acceleration compared with (i) the same reaction in an organic solvent, or (ii) the corresponding dry media reaction. This effect has been known for many years but in 2005 researchers in the group of K. Barry Sharpless published a systematic study into this phenomenon. (en)
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- On-water reaction (en)
- 水上反应 (zh)
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