pKa Data Compiled by R. Williams pKa Values INDEX Inorganic 2 Phenazine 24 Phosphates 3 Pyridine 25 Carboxylic acids 4, 8 Pyrazine 26 Aliphatic 4, 8 ... PHOSPHATES AND PHOSPHONATES CF3- 1.16, 3.93 57 CCl3- 1.63, 4.81 57 Phosphates NH3+CH2- 2.35, 5.9 57 Compound pK Ref. (–OOCCH2)2NH+CH2– --, 5.57 57 Phosphate 1.97, 6.82, 12.5 55 CHCl

2018年7月8日 · The pKa of trifluoroacetic acid is 0.52, indicating that this compound will primarily exist in the anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts. Volatilization from moist soil surfaces is not expected to be an important fate process as ...

D.H. Ripin, D.A. Evans 19-20 9 13 11 24.5 H2 ~36 *Values <0 for H2O and DMSO, and values >14 for water and >35 for DMSO were extrapolated using various methods. HCCH Substrate SubstrateSubstrate pKa H2O (DMSO) Substrate AMIDES HYDROCARBONS pKa H2OH(DMSO) pKa pKa2O (DMSO) H2O (DMSO) CH4 CH2=CHCH3 PhH …

此数据由哈佛大学的David Ripin and David Evans收集，包括以下化合物的 pKa 。 Inorganic Acids Alcohols, Oximes, Hydroxamic Acids, and Peroxides

Equilibrium pKa Table (DMSO Solvent and Reference) Hydrocarbons 20.117 21.822 22.522 17.317 Ph 18.019 26.122 Fluorenes X X = H 22.61 Me 22.31 Ph 17.91 tBu 24.421 SiMe3 21.5 26 SiPh3 18.6 26 = Fl-X

三氟乙酸（CF3COOH）是一种较强的无机酸，其pKa约为0.23-0.27。 由于含有三个氟原子，三氟乙酸的电子云密度较低，使其极性增强，因此其酸性较强。 三氯乙酸（CCl3COOH）的pKa值约为0.92，较之三氟乙酸要弱。

有机酸和无机酸的PKa值表，提供了不同酸在水溶液中的解离常数。

但CF3H的H酸性较弱（pKa为25-28），去质子化较为困难，加之CF3-稳定性差，很容易在碱中抗衡阳离子的作用下发生α-氟消除形成二氟卡宾中间体。 CF3-发生α-氟消除形成二氟卡宾（图片来源：参考资料[2]）

Trifluoroacetic acid (TFA) is a strong organic acid typically used as a solvent or acid catalyst. TFA is the CF3 analogue of acetic acid (AcOH) which due to the electron withdrawing effect of the fluorine atoms is much more acidic than AcOH. The pKa of TFA is …

X= CH3 CH2NO2 CH2F CH2Cl CH2Br CH2I CHCl2 CCl3 CF3 H HO C6H5 o-O2NC6H4 m-O2NC6H4 p-O2NC6H4 o-ClC6H4 m-ClC6H4 p-ClC6H4 MeOH i-PrOH t-BuOH c-hex3COH CF3CH2OH (CF3)2CHOH C6H5OH m-O2NC6H4OH p-O2NC6H4OH p-OMeC6H4OH 2-napthol ... pKa's of CH bonds at Nitrile, Heteroaromatic, and Sulfur Substituted Carbon Substrate pKa H2O (DMSO) SULFIDES PhSCH2X X ...

In CFX3X−, the fluorine can hold the electronegative charge quite well. It also exerts a strong inductive effect. In CBrX3X−, the bromine is less electronegative than the fluorine but is more polarizable, so I think it can hold the negative charge more efficiently.

2017年2月19日 · The pKa values of almost all carboxylic acids lie much above 0. But this is violated by trifluoroacetic acid(-0.25). How can this be justified?

2016年4月15日 · 化合物PKa表 星级： 5 页 化合物的pKa 星级： 33 页 有机酸无机酸pka值表 星级 ... (1 2.3)(1 .6)(0.3)CF3SO3H-1 4(7.9)(1 2.9)(1 5)(1 .8)(0.9)(32)(DMSO)(CF3)2CHOHCF3CH2OHt-BuOHMeOHi-PrOHHOHcis-CO2Htrans-CO2HHR=3.6, 1 0.3HO3.77H-0.25CF30.65CCl31 .29CHCl2-8.01 1 …

The pka of water and H 3O+ have been experimentally determined to be 14.0 and 0.0, respectively. Earlier values of 15.7 and –1.74, respectively are erroneous numbers proposed by scientists who made some errors in the calculated “rational” values. See: 1) Helv. Chim. Acta 2014, 97, 1. and 2) J. Chem. Educ. 2017, 94, 690.

2023年2月6日 · If you compare the pKa values of x-CH2CO2H, when x is F, pKa = 2.66, and x = CF3 gives [Ka = 3.06. So a single fluorine is more electron-withdrawing than a trifluoromethyl group. Except we know that's not true.

This experimental parameter is called "the pKa". The pKa measures how tightly a proton is held by a Bronsted acid. A pKa may be a small, negative number, such as -3 or -5. It may be a larger, positive number, such as 30 or 50. The lower the pKa of a …

中文名:全氟-1-丁磺酸,英文名:Nonafluorobutane-1-sulfonic acid,CAS:375-73-5,化学式:CF3 (CF2)3SO3H,分子量:300.1,密度:1.811 g/mL at 25 °C (lit.),沸点:112-114 °C/14 mmHg (lit.),闪 …

2020年12月30日 · 首先，ChEMBL数据库统计结果显示，虽然总体来说–CF3与–CH3的替换对小分子化合物的生物活性（IC50、Ki、Kd等）的影响无显著差异，但是有9.19%的化合物中–CH3替换为–CF3后，化合物活性可以提高一个数量级（图1），值得进一步的研究。 PDB数据库的统计分析表明，–CF3倾向于与Phe、Met、Leu 和Tyr作用，而–CH3倾向于与Leu、Met、Cys和Ile作用。 如果–CH3周围是Phe、His或者Arg，将其替换为 −CF3，则很可能会提高活性。 图1. 含–CH3 …

2017年6月28日 · Dean Toste教授与劳伦斯伯克利国家实验室的James P. O'Neil博士合作报道了一种高效快速构建C (sp3)-CF3键的方法，该反应以三氟甲基配位的Au (III)络合物为三氟甲基来源，B (C6F5)3 为关键催化剂，通过独特的“氟负离子回弹”机理（"fluoride-rebound" mechanism）可以得到多种不同结构脂肪烃的三氟甲基化产物。 反应过程中涉及三氟甲基C-F键的断裂与重新形成，因而可以结合18F同位素标记的氟源合成具有放射性三氟甲基的示踪剂用于PET技术中。 相关工 …

2018年6月22日 · 该研究以易于制备的α-三氟甲基酮和广谱的芳基硼酸作为原料，得到高Z 选择性的氟化-α,β-不饱和酮。 该方法的优点包括：（1）该反应代表了首例过渡金属催化与sp3杂化 …