在有原子氧的金属基板上生长的石墨烯的功能化:乙烯酸与环氧
Jaehoon Jung1, Hyunseob Lim, Junepyo Oh
1Surface and Interface Science Laboratory, RIKEN , Wako, Saitama 351-0198, Japan.
Journal of the American Chemical Society
|June 3, 2014
概括
形石墨烯的原子氧化形成稳定石墨烯酸盐,是一种新型中间体. 这一发现为石墨烯功能化和在催化和设备中的应用提供了新的途径.
科学领域:
- 材料科学 材料科学 材料科学
- 表面化学 表面化学
- 计算化学计算化学
背景情况:
- 石墨烯功能化对于开发先进材料和催化剂至关重要.
- 控制石墨烯的表面化学是释放其在各种应用中的潜力的关键.
研究的目的:
- 为了研究在表轴石墨烯上原子氧化的机制.
- 识别石墨烯的新型功能化途径和中间体.
主要方法:
- 使用周期密度函数理论 (DFT) 的计算.
- 在金属基板上生长的表轴石墨烯上模拟原子氧吸附.
主要成果:
- 原子氧化导致稳定的石墨烯酸酸中介的形成.
- 酸盐是一个局部最小值,由石墨烯 - 金属基板相互作用稳定.
- 在这些条件下,这种酸盐比石墨烯环氧化物更稳定.
结论:
- 原子氧化为石墨烯功能化提供了一条新的化学路径.
- 稳定石墨烯乙烯酸盐为基于石墨烯的新型应用提供了机会.
- 了解这种中间体有助于进步石墨烯化学和材料设计.
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.
Preparation of Epoxides
Overview
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
Acid-Catalyzed Ring-Opening of Epoxides
Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The...
Base-Catalyzed Ring-Opening of Epoxides
Due to their highly strained structures, epoxides can readily undergo ring-opening reactions through nucleophilic substitution, either in the presence of an acid or a base. The nucleophilic substitution reactions in the presence of acid are called acid-catalyzed ring-opening reactions, and nucleophilic substitution reactions in the presence of a base are called base-catalyzed ring-opening reactions. Epoxides undergo base-catalyzed ring-opening reactions in the presence of a strong nucleophile...
Reactivity of Enolate Ions
Enolate ions are formed by the acid–base reaction of a carbonyl compound with a base. This leads to deprotonation of the α hydrogen atom, leading to a resonance-stabilized enolate ion where one of the contributing structures is an oxyanion, which imparts additional stability. Therefore, the proton on the α carbon is more acidic in nature than that of other sp3-hybridized C–H bonds but less acidic than those in O–H bonds where the negative charge in the conjugate base is localized on the oxygen...
Regioselective Formation of Enolates
As depicted in the figure below, the unsymmetrical ketones can form two possible enolates: less substituted or more substituted enolates. Usually, the thermodynamic enolates are formed from the more substituted α-carbon atom, while the kinetic enolates are formed faster by deprotonation from the less substituted position. The thermodynamic enolates have lower energy, so they are more stable. But the energy required to form kinetic enolates is less.


