Tetrakis(triphenylphosphine)palladium pd(pph3)4_Kain Industrial Additive

[Background and Overview]^[1][2][3]

Palladium-on-carbon catalyst is a commonly used hydrogenation catalyst and coupling catalyst. It is widely used in organic synthesis Suzuki coupling reaction, Heck reaction and Sonogashira reaction. For a long time, the suzuki coupling reaction has used a homogeneous phosphorus ligand catalyst. Although the homogeneous catalyst has high activity and selectivity, the precious metal cannot be recovered after use, causing environmental pollution and resource waste. In recent years, researchers have begun to use supported palladium catalysts, such as palladium on carbon, as catalysts for synthetic coupling in Suzuki coupling reactions. However, the substrates vary widely, and a single palladium carbon cannot meet the needs of the reaction. Therefore, palladium carbon needs to be modified to enhance its activity.

Tetrakis(triphenylphosphine)palladium is a kind of compound with the molecular formula Pd[P(C₆H₅)₃]₄ compounds are often abbreviated as Pd(PPh3)4, or PdP4. It is a bright yellow crystalline solid that slowly turns brown when exposed to air. Tetrakis(triphenylphosphine)palladium is a complex with zero-valent palladium as the central atom and four triphenylphosphine as ligands. It is mainly used to catalyze C-C and C-B cross-coupling reactions. Through palladium-catalyzed coupling reactions, the synthesis of many organic complex molecules, including drugs, can be achieved. Three scientists from the United States and Japan, Heck, Nagishi, and Suzuki, won the 2010 Nobel Prize in Chemistry for their outstanding achievements in this area[5] . At present, tetrakis(triphenylphosphine)palladium, as an important cross-coupling reaction catalyst, has been successfully used in the synthesis of some drugs, pesticides, and organic functional molecules.

【Synthesis】^[1][2]

Method 1: In this method, the synthesis method of tetrakis(triphenylphosphine)palladium mainly involves three-step reactions:

1) PdCl2 undergoes coordination substitution reaction with triphenylphosphine in DMF to generate trans-dichlorobis(triphenylphosphine)palladium(II) intermediate;

2) Hydrazine hydrate reduces the 2-valent palladium in trans-dichlorobis(triphenylphosphine)palladium(II) to zero-valent palladium;

3) Finally, two chlorines leave, and the central atom coordinates with two triphenylphosphine to form tetrakis(triphenylphosphine)palladium.

These three-step reactions are carried out sequentially in the same reactor, and the yield can reach more than 95% by controlling the appropriate reaction conditions and feed ratio. Since the palladium in tetrakis(triphenylphosphine)palladium is in a zero-valent state and is easily oxidized and discolored, the entire operation should avoid an oxidizing environment and the product should be stored under an inert atmosphere such as nitrogen.

Method 2: Using palladium dichloride and triphenylphosphine as reaction raw materials, A as the solvent, and B as the reducing agent, the synthesis of tetrakis (triphenylphosphine) palladium was carried out through an oil bath heating reaction. The product The yield is close to 95%. The preparation process conditions are as follows: the reaction temperature is 140°C, the reduction temperature is 105°C, the molar ratio of PRh₃ and PdCl₂ is 4.5:1, solvent B and PdCl _{The molar ratio of 2} is 4:1. The feeding method is to dissolve the two separately and then mix them for reaction. The post-processing method is Y reagent washing, nitrogen pressure filtration, and vacuum packaging for low-temperature storage.

[Application]^[3][4]

Tetrakis(triphenylphosphine)palladium (0) is a palladium complex, commonly known as Catalyst B or Catalyst No. 2. It is a special catalyst for the synthesis of methylaminoavermectin benzoate. It can also be used Widely used in the following fields: important isomerization reactions – such as the isomerization of aromatics and alkenes; carbonylation, hydrosilylation, oxidation, C-C bond formation, alkyne ring trimerization; coupling reactions – such as aromatics Coupling reactions of base compounds and aryl halides, etc. Examples of its application are as follows:

Tetrakis (triphenylphosphine) palladium can be used as a catalyst to synthesize a diaryl acetylene. This method is to combine iodoaromatic hydrocarbons and diethoxyphosphonoacetylene in a solution containing tetrakis (triphenylphosphine) under a protective atmosphere. Sonogashira coupling reaction I is carried out in a solution system of palladium (phosphine), copper iodide and diisopropylamine to obtain 1-aryl-1′-diethoxyphosphonoacetylene; the 1-aryl-1′ – Sonogashira coupling reaction II between diethoxyphosphonoacetylene and brominated aromatics in a solution system containing tetrakis triphenylphosphine palladium, copper iodide and diisopropylamine under the action of potassium tert-butoxide, to obtain . During the coupling reaction, the molar ratio of iodoaromatic hydrocarbons to diethoxyphosphonoacetylene, tetrakistriphenylphosphine palladium, copper iodide and diisopropylamine is 1.2:0.8～1.2:0.04～0.06:0.04～0.06 :3～4,; the most preferred molar ratio is 1.2:1:0.05:0.05:3.5.

[Main reference materials]

[1] Liu Guihua, Ye Qingsong, Zuo Chuan, et al. Synthesis, structure and catalytic activity evaluation of tetrakis(triphenylphosphine)palladium[J]. Noble Metals, 2014, 35(1): 59-62.

[2] Guo Shoujie, et al. Synthesis of tetrakis(triphenylphosphine)palladium. Chemical Industry Management, 2017, 21: 88.

[3] Synthesis of several phenanthrene-containing compounds catalyzed by tetrakis(triphenyllin)ation

[4] Peng Lifen; Liu Yu; Zhang Siwei; Fu Xinliang; Li Xiaofang. A synthesis method of diaryl acetylene. CN201710071435.9, application date 2017-02-09