作为贝耶-维利格氧化过程中的异质化学选择性催化剂的sn-zeolite beta
1Instituto de Tecnología Química, UPV-CSIC, Avda. de los Naranjos s/n, 46022 Valencia, Spain. acorma@itq.upv.es
Nature
|July 27, 2001
概括
用锡修饰的化石β有效地利用过氧化催化基的Baeyer-Villiger氧化. 这种新型异质催化剂对乳形成具有很高的选择性,即使是不和子.
科学领域:
- 有机化学 有机化学
- 催化剂是一种催化剂.
- 材料科学 材料科学 材料科学
背景情况:
- 贝耶-维利格氧化将子转化为和乳,这在有机合成中至关重要.
- 为了提高效率和减少废物,人们更喜欢催化方法.
- 过氧化是一种比传统酸更绿色的氧化剂,但需要有效的催化剂.
研究的目的:
- 开发一种高度选择性和稳定的异质催化剂,用于贝耶-维利格氧化.
- 为了利用过氧化作为氧化剂,实现更可持续的工艺.
- 为了克服现有的催化剂的选择性限制,特别是不和子.
主要方法:
- 将锡 (重量1.6%) 纳入贝塔硫酸的框架.
- 测试锡修饰的化乙酸作为Baeyer-Villiger氧化过程中的异质催化剂.
- 使用过氧化作为和不和子的氧化剂.
主要成果:
- 锡改性化ββ热显示出作为异质催化剂的高效率和稳定性.
- 催化剂对所需的乳产品实现了>98%的选择性.
- 对于和和不和类都观察到出色的性能.
结论:
- 用锡修改的β化石是一种有效的催化剂,用于使用过氧化的Baeyer-Villiger氧化.
- 催化剂的高选择性归因于直接激活,与其他方法不同.
- 这为合成乳和 Ester提供了一个有前途的绿色和选择性途径.
相关概念视频
Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
Regioselectivity and Stereochemistry of Hydroboration
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
Reactions of Aldehydes and Ketones: Baeyer–Villiger Oxidation
Baeyer–Villiger oxidation converts aldehydes to carboxylic acids and ketones to esters. The reaction uses peroxy acids or peracids and is often catalyzed by acid. The reaction is named after its pioneers, Adolf von Baeyer and Victor Villiger. The reaction is achieved by a wide range of peracids such as m-chloroperoxybenzoic acid (mCPBA), perbenzoic acid (C6H5COOOH), peracetic acid (CH3COOOH), hydrogen peroxide (H2O2), and tert-butyl hydroperoxide (t-BuOOH).
The carbonyl center is activated by...
The carbonyl center is activated by...
α-Bromination of Carboxylic Acids: Hell–Volhard–Zelinski Reaction
The method to achieve α-brominated carboxylic acids using a mixture of phosphorus tribromide and bromine is known as the Hell–Volhard–Zelinski reaction. The reaction is catalyzed by phosphorus tribromide, which can be used directly or produced in situ from red phosphorus and bromine. The mechanism comprises PBr3 catalyzed conversion of acid to acid bromide and hydrogen bromide. The acid bromide enolizes to its enol form in the presence of HBr. The nucleophilic enol attacks the bromine molecule...
Heterogeneous Catalysis
Heterogeneous catalysis involves a catalyst in a different phase from the reactants. It is a process where the catalyst and the reactants are in distinct phases, typically solid and gas or liquid.Most heterogeneous catalysts are metals, metal oxides, or acids. The list includes transition metals like iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum (Pt), chromium (Cr), manganese (Mn), tungsten (W), silver (Ag), and copper (Cu). These metals possess partially vacant d orbitals that...


