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相关概念视频

ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH301:11

ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3

6.1K
All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...
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Electrophilic Aromatic Substitution: Nitration of Benzene01:20

Electrophilic Aromatic Substitution: Nitration of Benzene

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The nitration of benzene is an example of an electrophilic aromatic substitution reaction. It involves the formation of a very powerful electrophile, the nitronium ion, which is linear in shape. The reaction occurs through the interaction of two strong acids, sulfuric and nitric acid.
6.1K
Basicity of Heterocyclic Aromatic Amines01:25

Basicity of Heterocyclic Aromatic Amines

6.1K
Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).
6.1K
Stability of Substituted Cyclohexanes02:30

Stability of Substituted Cyclohexanes

12.7K
This lesson discusses the stability of substituted cyclohexanes with a focus on energies of various conformers and the effect of 1,3-diaxial interactions.
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
12.7K
Basicity of Aromatic Amines01:18

Basicity of Aromatic Amines

7.2K
The basicity of aromatic amines is much weaker than that of aliphatic amines due to the involvement of the lone pair of electrons over the N atom in resonance with the aryl rings. Generally, the electron-donating ability of any substituents on the aryl ring of aromatic amines increases the basicity of the amine by increasing electron density, and hence the availability of lone pair on the nitrogen. On the other hand, electron-withdrawing functional groups on the aryl ring of amines decrease the...
7.2K
Regioselectivity and Stereochemistry of Hydroboration02:36

Regioselectivity and Stereochemistry of Hydroboration

8.2K
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...
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脊柱异构化以提高10个酸替代双醇的热稳定性和降低机械灵敏度.

Jingwei Meng1, Teng Fei1,2, Jinxiong Cai1

  • 1Experimental Center of Advanced Materials, School of Materials Science & Engineering, Beijing Institute of Technology, Beijing 100081, China.

ACS applied materials & interfaces
|October 6, 2023
PubMed
概括
此摘要是机器生成的。

研究人员开发了一种新的高能氧化剂,3,3

关键词:
脊柱的异构化 脊柱的异构化比皮拉 (bipyrazole) 是一种可怕的药物.高能量密度氧化剂高能量密度氧化剂热稳定性 热稳定性三二甲基二氧化碳的含量是多少

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科学领域:

  • 能量材料科学 能量材料科学
  • 有机合成 有机合成
  • 绿色化学 绿色化学

背景情况:

  • 甲 (AP) 是一种广泛使用的氧化剂,但对环境造成了担忧.
  • 开发新型,环保,高能量密度氧化剂至关重要.
  • 三甲基组是设计先进氧化剂的一个有前途的替代剂.

研究的目的:

  • 设计和合成新的基组替代双醇作为高能量密度氧化剂.
  • 为了研究脊柱异构对这些化合物的特性的影响.
  • 开发比传统氧化剂更安全,更稳定的替代品.

主要方法:

  • 3,3',5,5'-tetranitro-1,1'-bis(trinitromethyl) -1H,1'H-4,4'-bipyrazole (3) 通过骨干异构化进行合成.
  • 合成化合物的热稳定性测试 (Td).
  • 合成化合物的机械灵敏度测试 (冲击和摩擦灵敏度).

主要成果:

  • 与其同位素4 (Td = 125 °C) 相比,化合物3表现出增强的热稳定性 (Td = 156 °C).
  • 化合物3比同位素4 (IS = 9 J,FS = 215 N) 显示出更好的机械灵敏度 (IS = 13 J,FS = 240 N).
  • 合成的氧化剂的特性与氨基丁胺 (DNA) 相似.

结论:

  • 脊柱异构化是一种有效的策略,用于调整由基组替代的双pyrazoles 的特性.
  • 化合物3显示出作为一种高能量密度氧化剂的有前途潜力,具有更好的安全特性.
  • 这项研究有助于开发更绿色,更高效的能源材料.