Benzeneboronic Acid, P-Iodo-

Phenylboronic acid, p-iodine, has a chemical structure composed of a benzene ring, a boric acid group, and a para-iodine atom.
Looking at the benzene ring, this is a stable six-membered ring structure, composed of six carbon atoms connected to each other by conjugated double bonds, and has aromatic properties. This conjugated system endows the benzene ring with special chemical stability and electron cloud distribution characteristics.
Boric acid group (-B (OH) -2) is attached to the benzene ring. The boron atom has electron-deficient properties and is connected to two hydroxyl groups. The electron-deficient properties of boron atoms in the boric acid gene can exhibit unique chemical properties, such as complexation reactions with compounds containing o-diol structures, and are widely used in organic synthesis and materials science.
The iodine atom in the para-position, iodine is a halogen element, has a large atomic radius and electronegativity. It is connected to the para-position of the benzene ring. Due to the electronic effect and spatial effect of the iodine atom, it has a significant impact on the electron cloud density distribution and chemical reaction activity of the benzene ring. The presence of iodine atoms can reduce the electron cloud density of the adjacent and para-position of the benzene ring, which affects the activity and selectivity of the reaction in the electrophilic substitution reaction. At the same time, iodine atoms can be used as important functional groups to participate in a variety of organic reactions, such as coupling reactions, providing the possibility for the construction of more complex organic molecular structures.
In this way, phenylboronic acid, the chemical structure of -iodine-by the interaction of benzene ring, boric acid group and iodine atom, presents unique chemical properties and reactivity, which are of great significance in many fields of organic chemistry.

P-iodoboronic acid (Benzeneboronic Acid, P-iodo-) is a key reagent in organic synthesis. It has unique physical properties. Looking at its appearance, it is normally white to off-white crystalline powder, which is easy to use and operate.
When it comes to the melting point, the melting point of p-iodoboronic acid is about 242-248 ° C. The characteristics of the melting point are crucial in the identification and purification of this substance. Its purity can be determined by the melting point. If impurities are mixed, the melting point often decreases or the melting range widens.
Furthermore, its solubility is also an important physical property. In organic solvents, p-iodophenylboronic acid has a certain solubility in common organic solvents such as ethanol and dichloromethane. Moderate heating or stirring can increase its solubility. However, in water, its solubility is relatively limited. This solubility characteristic needs to be carefully considered in the selection of reaction solvents, product separation and purification steps in organic synthesis. For example, if the reaction system requires the participation of aqueous phase, its water solubility is poor, or a phase transfer catalyst needs to be added to promote the smooth progress of the reaction; and when the product is separated, a suitable extractant can be selected according to its solubility in different solvents to achieve effective separation.
The physical properties of p-iodophenylboronic acid are like cornerstones in the field of organic synthesis, which have a profound impact on the implementation of related chemical reactions and the acquisition of products. Organic synthesis practitioners must be familiar with them before they can use them flexibly.

The common preparation routes of p-iodo- (Benzeneboronic Acid, P-iodo-) are as follows.
One is the metallization reaction of halogenated aromatic hydrocarbons. Using p-iodobromobenzene as the starting material, it interacts with strong bases such as butyl lithium at low temperature to form aryl lithium intermediates. This intermediate is extremely active, and then reacts with borate esters, such as trimethyl borate, and the resulting borate ester product is hydrolyzed acidically to obtain p-iodoboronic acid. This process requires strict control of the reaction temperature and the amount of reagents to ensure that the reaction proceeds according to the expected path. Because aryl lithium is extremely active, improper operation is prone to side reactions.
The second is a palladium-catalyzed coupling reaction. In the presence of a palladium catalyst (such as tetra (triphenylphosphine) palladium, etc.) and ligands (such as tri-tert-butyl phosphine, etc.), the reaction system also requires the participation of bases (such as potassium carbonate, sodium carbonate, etc.), which can assist in the activation of halogenated aromatics and promote the circulation of palladium catalysts. This method has good selectivity and yield, because the palladium catalyst can effectively guide the reaction orientation, and the reaction conditions are relatively mild and easier to control.
Another Grignard reagent method is available. The p-iodobromobenzene is reacted with magnesium chips in anhydrous ether or tetrahydrofuran to make Grignard's reagent. Subsequently, Grignard's reagent reacts with borate ester, and the product is hydrolyzed to obtain the target product p-iodophenylboronic acid. In this way, the preparation of Grignard's reagent requires an absolutely anhydrous environment, otherwise Grignard's reagent is easy to react violently with water and fail, so the reaction environment requirements are strict.
The above methods have their own advantages and disadvantages. In practical application, it is necessary to comprehensively weigh factors such as raw material availability, cost considerations, and product purity requirements to choose the most suitable method.

There are several common methods for preparing p-iodoboronic acid (Benzeneboronic Acid, P-iodo-). First, it can be obtained by the metallization reaction of halogenated aromatics and the reaction of borate esters. First, take p-iodobromobenzene and treat it with n-butyl lithium (n-BuLi) at a low temperature (such as -78 ° C) to form a lithium reagent. This lithium reagent is very active, and then reacts with trimethyl borate (B (OMe)). After the reaction is completed, it can be hydrolyzed to obtain p-iodoboronic acid.
Second, it can also be prepared by a palladium-catalyzed coupling reaction. Using p-iodohalobenzene and pinacol borate (PinB (OH)) as raw materials, in the presence of palladium catalysts (such as tetra (triphenylphosphine) palladium (Pd (PPh ₃)₄) ）、 base (such as potassium carbonate (K 2O CO))), the reaction is heated in a suitable solvent (such as a mixed solvent of dioxane and water). This reaction goes through the steps of oxidative addition, metallization, reduction and elimination, and finally produces the target product p-iodophenylboronic acid.
Furthermore, the Grignard reagent method is also feasible. The Grignard reagent is prepared by reacting p-iodohalobenzene with magnesium shavings in anhydrous ether or tetrahydrofuran. The Grignard reagent is then reacted with borate ester and then hydrolyzed with acid to obtain p-iodophenylboronic acid. This method has its own advantages and disadvantages, and it needs to be carefully selected according to the actual situation, such as the availability of raw materials, cost, reaction conditions and other factors.

In the chemical reaction of p-iodophenylboronic acid, there are several things to pay attention to. First, its chemical properties need to be carefully controlled. This substance has some characteristics of boric acid, and can be formed into salts when exposed to strong bases, and the benzene ring and iodine atoms also have specific reactivity. During storage, moisture should be avoided, because humidity can cause hydrolysis of boric acid groups, which affects its purity and reactivity.
Second, the choice of solvent is crucial. A suitable solvent can increase the solubility of the reactants and help the reaction proceed uniformly. In most reactions, polar organic solvents such as dichloromethane, N, N-dimethylformamide (DMF) are quite commonly used. Methylene dichloride has a low boiling point and is easy to be separated later; DMF has strong polarity and can dissolve a variety of organic compounds, which is conducive to the reaction. When selecting a solvent, it is also necessary to consider its compatibility with the reactants and products to avoid adverse side reactions.
Third, temperature control is also critical. Different reactions have different temperature requirements. Heating can speed up the reaction rate, but too high temperature or increase side reactions, such as iodine atom removal. Therefore, it is necessary to find the appropriate temperature according to the specific reaction. For example, some coupling reactions often need to be carried out under heating reflux conditions. At this time, the temperature should be precisely controlled to make the reaction occur smoothly.
Fourth, the choice and dosage of catalyst. Reactions involving p-iodophenylboronic acid, such as Suzuki coupling reaction, require palladium and other metal catalysts. The activity and dosage of the catalyst are directly related to the reaction efficiency and yield. If the dosage is too small, the reaction will be slow or incomplete; if it is too much, it will increase the cost and lead to impurities. The catalyst dosage should be optimized according to the reaction scale and substrate activity.
Finally, safety protection should not be ignored. P-iodophenylboronic acid and related reactants may be toxic and irritating. Appropriate protective equipment should be worn during operation, such as gloves, goggles, etc. Work in a well-ventilated environment to avoid inhalation or contact with skin and eyes to ensure the safety of experimenters.