Sodium Triacetylborohydride (link:https://www.bloomtechz.com/synthetic-chemical/organic-intermediates/sodium-triacetoxyborohydride-cas-56553-60-7.html) is a white powder with the chemical formula NaBH(OAc)₃ and its molecular weight is about 252.06 g/mol. The compound has a variety of physical properties, with a point between 150-155°C, relatively light density and good solubility. The density is about 1.18 g/cm³. This means that the compound is relatively light and, under certain conditions, can float on many solvents. This property makes Sodium Triacetoxyborohydride easy to use in the laboratory. These physical properties make it an important reducing agent and play an important role in organic synthesis.
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The following is a brief introduction about the main chemical properties of the compound:
1. Reducibility:
Sodium Triacetylborohydride is a strong reducing agent that can reduce many organic compounds to lower oxidation states. For compounds containing oxygen functional groups, such as aldehydes, ketones, acids and esters, Sodium Triacetoxyborohydride will usually be selectively reduced to the corresponding alcohols or hydroxyl compounds. For compounds containing sulfur functional groups, such as mercaptans and disulfides, the reducing agent also has strong reducing properties.
2. Reactivity:
In many organic syntheses, Sodium Triacetoxyborohydride is also used as a catalyst for reduction reactions. In these reactions, the compound is typically added to the reaction system to react with other chemicals. For example, it can react with carboxylic acid anhydrides to generate corresponding alcohols, or react with aromatic ketones to generate corresponding aromatic alcohols, etc. In addition, Sodium Triacetoxyborohydride can also be used as a catalyst for condensation reactions, such as condensation reactions between carboxylic acids and amines.
3. Stability:
Although Sodium Triacetoxyborohydride is a strong reducing agent, it is more stable than other commonly used reducing agents such as sodium borohydride. During storage and use, the compound is not easily affected by conditions such as air, moisture and temperature. At the same time, it should also be noted that Sodium Triacetoxyborohydride should avoid contact with oxidizing agents, such as hydrogen peroxide or potassium permanganate, otherwise dangerous reactions will occur.
4. Reversibility:
The reduction reaction of Sodium Triacetoxyborohydride is reversible, so some chemical transformations can be selectively performed by controlling the reaction conditions. For example, by controlling the position of the electronically hindering group, the carbonyl group in aromatic ketones can be selectively reduced without affecting the reaction at other positions.
5. Specificity:
5.1. Efficiency: Sodium Triacetoxyborohydride is a very efficient reducing agent, it can quickly reduce a variety of functional groups, such as nitro, aldehyde, ketone, ester, etc., and its reaction speed is faster than other commonly used reducing agents such as sodium bisulfite, Lithium Aluminum Hydride etc. are faster.
5.2. Selectivity: Sodium Triacetoxyborohydride has good selective reduction of different functional groups, for example, it can selectively reduce ketones without affecting functional groups such as enol and carboxylic acid, which makes it the preferred reducing agent for many synthetic chemists.
5.3. Safety: Compared with other reducing agents, such as lithium aluminum hydride, sodium bisulfite, etc., the use of Sodium Triacetoxyborohydride is safer because it will not release hydrogen gas under water or acidic conditions, and its use is also Complicated protective measures are not required.
5.4. Convenience: Sodium Triacetoxyborohydride is easy to prepare, has a long storage life, and can be stored and used at room temperature. In addition, Sodium Triacetoxyborohydride can also be mixed with other reducing agents to enhance its reducing ability or adjust the reaction conditions.
5.5. Wide range of applications: Sodium Triacetoxyborohydride plays an important role in many organic synthesis reactions, such as the preparation of organic compounds such as alcohols, ethers, amines, and alkenes. In addition, it can also be used to prepare and protect functional groups such as hydroxyl, amino, and amine groups, and to reduce organic excess and waste liquids in the production process.
Sodium Triacetylborohydride has high specificity in the reduction reaction. For example, in polyfunctional carboxylic acids or ketones, only one functional group will be reduced to the corresponding alcohol or hydroxyl compound, while the other functional groups are not affected. This makes Sodium Triacetoxyborohydride highly selective in organic synthesis and can reduce the generation of other side reactions.
In conclusion, Sodium Triacetoxyborohydride, as an important reducing agent, has strong reducibility and stability. It has high specificity and selectivity in chemical reactions, so it is widely used in the fields of drug synthesis, organic synthesis and material science.
At room temperature, Sodium Triacetoxyborohydride has high thermal and chemical stability, and can be stored and used under normal experimental conditions.
1. Molecular structure:
The molecular structure of Sodium Triacetoxyborohydride is composed of three acetoxy groups and a borohydride ion. The structure of the borohydride ion is similar to a regular tetrahedron, in which the B atom is located at the center, and three OAc groups are distributed equidistantly and equiangularly around it, and each H atom is connected to an OAc group to form a bond with the B atom. In addition to borohydride ions, sodium ions also play an important role in structure stabilization in the lattice.
2. Crystal structure:
The crystal structure of Sodium Triacetylborohydride was obtained in 1973 by G. W. Parshall et al. It is monoclinic with space group P21/c. The unit cell parameters are a = 13.236 Å, b = 16.145 Å, c = 9.048 Å, and β = 96.74°. The unit cell contains four molecules, each of which interacts with other molecules through hydrogen bonds, forming a three-dimensional network structure. In the lattice, the borohydride ion forms hydrogen bonds with three different OAc groups through H atoms, making the distance between them about 1.2 Å. The sodium ion forms an ionic bond with one of the three OAc groups.
3. Spectroscopy properties:
Sodium Triacetylborohydride has many characteristic spectral properties, which can be used for its qualitative and quantitative analysis. For example, there is an obvious C=O stretching vibration peak at about 1700 cm-1 in its IR spectrum. Meanwhile, there are also absorption bands caused by BH and CH bonds. In its 1H NMR spectrum, the H atoms of the hydride ion give rise to a characteristic chemical shift of approximately -4 ppm. In addition, around boron ions (i.e., OAc and H atoms), there is also a local magnetic field effect that leads to the splitting and changing of the chemical shift.
4. Solubility properties:
Sodium Triacetoxyborohydride has good solubility in water, about 1.5 g can be dissolved in 100 mL of water. Its solubility is higher in organic solvents such as ethanol, methanol and dimethylformamide. Because of its strong alkalinity, it is unstable in acidic solution and easily decomposes to produce hydrogen.
In conclusion, Sodium Triacetoxyborohydride has a unique molecular structure and characteristic spectroscopic properties. These properties are related to its wide application, for example, it can be used to reduce compounds such as ketones, aldehydes and enones, and can also be used to synthesize boron-containing heterocyclic compounds. Understanding its structural properties is of great significance for understanding its application mechanism, advantages and disadvantages. It has the advantages of high efficiency, safety, convenience, and good selectivity, and is widely used in the field of organic synthesis.