增强的氧化物易斯基本性克服了无菌的挫折感
Addis Getahun1, John S Wenger1, Timothy C Johnstone1
1Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California 95064, United States.
Organometallics
|September 26, 2025
概括
与素和素氧化物相比,较重的素氧化物显示出增强的易斯基性. 这种增加的基本性使得氧化物能够连接易斯酸,即使使用了大量的替代剂,克服了硬质障碍.
科学领域:
- 有机金属化学 有机金属化学
- 主组 化学 主组 化学
- 易斯的酸相互作用
背景情况:
- 氧化物由于电子效应而具有稳定的P-O键,包括O-to-P背键.
- 酸单位中的氧原子表现出易斯基本性,受中央酸的电子性质的影响.
- 反向结合的强度随着化物原子数的增加而下降,这可能会在更重的同源中增强易斯基本性.
研究的目的:
- 为了比较R3PnO物种 (Pn = P,As,Sb) 的易斯酸结合能力.
- 为了研究固体质量对易斯酸 adduct 形成的影响.
- 评估增强的基基性在克服硬质障碍中的作用.
主要方法:
- 合成和表征各种R3PnO化合物.
- 研究易斯酸添加物与主要组易斯酸的形成,包括B-(C6F5)3.3.
- 结合性亲缘关系的比较,跨系列的pnictogen氧化物与不同的硬质需求.
主要成果:
- 绝缘散体显著阻碍了易斯酸在氧化物 (R3PO) 和氧化物 (R3AsO) 中的结合.
- 高度受阻的Dipp3PO和Dipp3AsO (Dipp = 2,6-二二甲) 无法结合强大的易斯酸B-(C6F5) 3.3.
- 斯蒂宾氧化物 (R3SbO) 显示出增强的易斯基性,使得即使使用像Dipp3SbO这样的体替代物,也可以形成添加物.
结论:
- R3PnO化合物的易斯基本性从P显著增加到Sb,克服了固态限制.
- 较重的平氧化物是优质的易斯基,能够与强大的易斯酸形成稳定的附加物,而不考虑硬质障碍.
- 这项研究突出了用于设计易斯酸 adducts 的 pnictogen 氧化物的可调节电子特性.
相关概念视频
01:10Radical Reactivity: Steric Effects
2.4K
The presence of electron-donating, electron-withdrawing, or conjugating groups adjacent to a radical center, imparts electronic stabilization to the radicals. Examples of such electronically-stabilized radicals are triphenylmethyl, tetramethylpiperidine‐N‐oxide, and 2,2‐diphenyl‐1‐picrylhydrazyl. These radicals are remarkably stable and are known as persistent radicals. Some of the persistent radicals can even be isolated and purified.
Along with electronic...
Along with electronic...
2.4K
02:36Regioselectivity and Stereochemistry of Hydroboration
9.4K
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.
9.4K
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
20.7K
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
20.7K
01:18Directing and Steric Effects in Disubstituted Benzene Derivatives
3.9K
When disubstituted benzenes undergo electrophilic substitution, the product distribution depends on the directing effect of both substituents. When the directing effects of both substituents reinforce each other, a single product is obtained. For example, bromination of p-nitrotoluene occurs ortho to the methyl group and meta to the nitro group, which is the same position, resulting in a single product. However, if the directing effects of the two groups oppose each other, the...
3.9K
03:08Hydroboration-Oxidation of Alkenes
11.1K
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.
11.1K
02:16Resonance and Hybrid Structures
25.2K
According to the theory of resonance, if two or more Lewis structures with the same arrangement of atoms can be written for a molecule, ion, or radical, the actual distribution of electrons is an average of that shown by the various Lewis structures.
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.
25.2K