Lithium aluminium hydride

This is a special white powder.

It is used in labs to make new things. It can even help hold gas for cars.

Be very careful with this powder. It reacts fast if it touches water. This makes a gas that can catch fire.

Sometimes the powder looks gray. This happens if it is not pure. It can also turn white if it touches air.

People use it to change how things are built. It is very strong at this job. It can turn many things into alcohols.

Scientists study it to help find new ways to power cars. It is a very busy little powder.

Lithium aluminium hydride is a special chemical. People call it LAH for short.

It is a white solid. Sometimes it looks gray because of tiny bits of dirt.

Scientists first found it in 1947.

LAH is a reducing agent. This means it helps change how other things are built. It is very strong at this job. It can turn many things into alcohols. This is useful in organic chemistry.

This powder is very reactive. It reacts violently if it touches water. This reaction lets out hydrogen gas.

Because it can catch fire easily, it is called pyrophoric. People must keep it in special plastic sacks. This keeps moisture out.

Some people think LAH can help power cars. It can hold a lot of hydrogen. This could be used in fuel cells. But there are problems with this. It needs very high heat to release the gas. It also needs very high pressure to make more. Scientists are still studying how to make it work better.

Lithium aluminium hydride is a very important chemical compound. Scientists often call it LAH for short.

It is a white solid in its pure form. However, many samples look gray because of tiny bits of contamination. This material is used as a reducing agent in organic synthesis. A reducing agent is a substance that helps change how other molecules are built.

This makes LAH a vital tool for chemists working with complex structures.

LAH works by changing the way atoms are connected in other substances. It is much more powerful than a similar chemical called sodium borohydride. This strength comes from the Al-H bond being weaker than the B-H bond.

In the lab, LAH can turn esters and carboxylic acids into alcohols. It can also turn amides and nitriles into amines. The way it works depends on how it reacts with different parts of a molecule. It can even reduce alkyl halides into alkanes.

Researchers first discovered this compound in 1947. It was found by three scientists named Finholt, Bond, and Schlesinger. Since then, people have found many ways to make it. One way involves reacting lithium hydride with aluminium chloride. Another industrial method starts by making sodium aluminium hydride under high pressure.

Scientists can also make it using metallic aluminium and lithium hydride. They use a tiny amount of TiCl3 to help the reaction go well.

There are many important facts to know about how LAH behaves. It is a very reactive substance that reacts violently with water. This reaction releases hydrogen gas, which can be used in a laboratory.

Because it can catch fire easily, it is called pyrophoric. This means it must be kept in moisture-proof plastic sacks. LAH also contains 10.6 wt% hydrogen by weight. This makes it an interesting idea for storing hydrogen for future fuel cell vehicles.

Even though it is useful, LAH can be quite difficult to handle. It is unstable and can decompose if it is stored for a long time. Some people have even used CO2 fire extinguishers on it, but that can make fires worse. Because of these safety issues, some industries use a different chemical called sodium bis (2-methoxyethoxy)aluminium hydride. This newer version is safer and easier to use for large jobs. Still, LAH remains a famous and powerful tool in the world of science.

Lithium aluminium hydride, or LAH, is a powerful inorganic compound. It is used primarily as a reducing agent in organic synthesis. A reducing agent is a substance that changes other molecules by adding electrons or hydrogen.

This makes LAH a vital tool for chemists. It can transform many different types of organic structures. Because it is so effective, it is a staple in many chemistry laboratories.

Chemists use LAH to change how atoms are connected in various molecules. It is more powerful than sodium borohydride. This extra strength comes from its chemical structure. The aluminium-hydrogen (Al-H) bond is weaker than the boron-hydrogen (B-H) bond.

This weaker bond allows LAH to react more vigorously. For example, it can convert esters and carboxylic acids into primary alcohols. It also turns amides, nitriles, and oximes into amines. It can even reduce quaternary ammonium cations into tertiary amines.

In its pure form, LAH is a colorless solid. However, most commercial samples appear gray due to contamination. These impurities are often harmless and easily separated from the final products.

To get a pure sample, scientists use a process called recrystallization from diethyl ether. Large-scale purification often uses a Soxhlet extractor. If a sample is old and has been exposed to air, it might look white. This happens because it has absorbed moisture to form lithium hydroxide and aluminium hydroxide.

Researchers discovered LAH in 1947. The discovery was made by Finholt, Bond, and Schlesinger. Since then, several ways to create the compound have been developed. One common method reacts lithium hydride (LiH) with aluminium chloride (AlCl3).

An industrial method involves first making sodium aluminium hydride (NaAlH4) using high pressure and temperature. Another way uses metallic aluminium and lithium hydride. This alternative method uses a small amount of TiCl3 as a catalyst to help the reaction. This specific method is useful because it avoids creating salt as a byproduct.

LAH is a highly reactive and energetic substance. It reacts violently with water to release hydrogen gas (H2).

This reactivity is why the powder is called pyrophoric. Pyrophoric means it can catch fire spontaneously in air. To stay safe, it is often packed in moisture-proof plastic sacks. Some versions contain mineral oil to stop reactions with moisture in the air. Because of these dangers, scientists must handle it with extreme care in fume hoods or dry boxes.

Beyond organic chemistry, LAH has potential uses in energy science. It contains 10.6 wt% hydrogen by weight. This high hydrogen content makes it a candidate for hydrogen storage. Scientists are studying if it could store fuel for future hydrogen-powered vehicles.

However, there are challenges. To get all the hydrogen out, you must heat it above 400 °C. Also, recycling the material back into LAH requires extremely high pressure, over 10,000 bar. These factors make its use in transportation difficult for now.

Finally, it is important to understand how LAH breaks down. It is metastable at room temperature. This means it is stable for a while, but will eventually decompose. Over long periods, it slowly turns into lithium hexahydridoaluminate and LiH. This breakdown can happen faster if titanium, iron, or vanadium are present. When heated, it follows a three-step decomposition process. It begins by melting between 150 and 170 °C. Eventually, at very high temperatures, it converts into lithium aluminium (LiAl).