相关实验视频
Updated: Jul 12, 2026

06:45
Negative Additive Manufacturing of Complex Shaped Boron Carbides
Published on: September 18, 2018
概括
研究人员通过一种新的反应合成了无形化 (BN) 管. 通过电子显微镜观察到的这些独特的空心BN结构,为材料科学提供了新的可能性.
科学领域:
- 材料科学 材料科学 材料科学
- 无机化学 无机化学
- 纳米技术纳米技术
背景情况:
- 化 (BN) 是一种多功能陶材料,具有多种应用.
- 新型BN形态的合成对于推进材料特性至关重要.
- 现有的BN合成方法经常产生散装或非管状形式.
研究的目的:
- 合成和描述化的新型空心管状结构.
- 为了研究无形BN的转化为流体形式.
- 探索合成的BN管的形态和结构特征.
主要方法:
- 无形化 (BN) 由B-三甲和金属合成.
- 在1100°C的温度下进行热处理,以诱导相变.
- 使用扫描电子显微镜 (SEM) 和传输电子显微镜 (TEM) 进行表征.
- 使用选区电子衍射 (SAED) 分析结构性质的分析.
主要成果:
- 观察到空洞的管状化结构的以前未报告的形态.
- 最大的管子大约有3微米的外径和50-100微米的长度.
- SEM和TEM证实了管状形态,而管壁呈现出流层结构.
- 确定了管生长的插入点,这表明了潜在的形成机制.
结论:
- 乙三博拉与金属的反应提供了一条通往新型空心管状化的途径.
- 将无形BN加热到1100°C就产生了流层结构,形成了这些独特的管子.
- 这些空心BN管的形成机制需要进一步研究.
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.
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
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.
Preparation of Nitriles
One of the common methods to prepare nitriles is the dehydration of amides. This method requires strong dehydrating agents like phosphorous pentoxide or boiling acetic anhydride for converting amides to nitriles. Another reagent namely, thionyl chloride also accomplishes the dehydration of amides, where amide acts as a nucleophile. The first step of the mechanism involves the nucleophilic attack by the amide on the thionyl chloride to form an intermediate. In the next step, the electron pairs...

