碳二胺的螺旋感选择性聚合:从阿基拉单体中构建永久光学活性聚合物
Gonglu Tian1, Yujie Lu, Bruce M Novak
1Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA.
Journal of the American Chemical Society
|April 1, 2004
概括
同体基质的催化剂使得状体的单体具有选择性聚合的螺旋感. 具有特定基的聚合物表现出稳定的光学活性,证明了对聚合物结构和特性的控制.
科学领域:
- 聚合物化学 聚合物化学
- 催化剂是一种催化剂.
- 立体化学是一种立体化学.
背景情况:
- 通过使用同质性催化剂,研究用螺旋感选择性聚合阿基拉单体.
- 了解聚合控制 (动力与热力学) 通过奇拉碳胺聚合物的突变旋转研究.
研究的目的:
- 为了探索使用特定的同化基催化剂, (S-BINOL) Ti ((OiPr) 2.2) 探索阿基拉碳二胺的聚合.
- 评估由此产生的聚合物的不对称感应和热稳定性.
主要方法:
- 使用 (S-BINOL) Ti(OiPr) 聚合各种阿基拉性碳二胺单体2.
- 聚合物特性分析,包括产量,不对称感应和加热时的种族化行为.
- 聚-7 薄膜的光学性能的表征.
主要成果:
- 阿希拉尔碳二胺被聚合,产量很好 (86-95%) 和不同程度的不对称诱导.
- 在加热后从具有对称基组 (多-3, -4, -5) 的单体中衍生出来的聚合物.
- 具有非对称的基组 (多-6,多-7) 的聚合物产生了耐种族化的光学活性聚合物.
- 聚-7的薄膜表现出高的不透明度.
结论:
- 这项研究表明,成功地通过螺旋感选择性聚合化Achiral碳二胺.
- 在单体中存在特定非对称的基,决定了光学稳定的聚合物的形成.
- 这种方法可以控制聚合物的立体化学和特性,由于Poly-7薄膜的色性质,可以提出潜在的应用.
相关概念视频
Carbon Skeletons
Life on Earth is carbon-based, as all macromolecules that make up living organisms contain carbon atoms. All organic compounds have a carbon backbone. Each carbon atom is tetravalent and can bond with four other atoms, making it an extraordinarily flexible component of biological molecules. Because carbon’s valence electrons are stable, it rarely becomes an ion. As the carbon chain increases in length, structural modifications such as ring structures, double bonds, and branching side chains...
Structures of Carboxylic Acid Derivatives
Structure of Carboxylic Acid Derivatives
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
Aromatic Hydrocarbon Cations: Structural Overview
Cycloheptatriene is a neutral monocyclic unsaturated hydrocarbon that consists of an odd number of carbon atoms and an intervening sp3 carbon in the ring. The three double bonds in the ring correspond to 6 π electrons, which is a Huckel number, and therefore satisfies the criteria of 4n + 2 π electrons. However, the intervening sp3 carbon disrupts the continuous overlap of p orbitals. As a result, cycloheptatriene is not aromatic.
Removing one hydrogen from the intervening CH2 group with both...
Removing one hydrogen from the intervening CH2 group with both...
Anionic Chain-Growth Polymerization: Overview
The polymerization process that involves carbanion as an intermediate is called anionic polymerization. It is also a type of addition or chain-growth polymerization. Anionic polymerization gets initiated by a strong nucleophile such as an organolithium or a Grignard reagent. The most commonly used initiator for anionic polymerization is butyl lithium. Monomers involved in anionic polymerization must possess a vinyl group bonded to one or two electron-withdrawing groups. For instance,...
Cationic Chain-Growth Polymerization: Mechanism
The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the generated carbocation,...


