Flammable organic compounds when wet

Most of the flammable organic compounds in contact with moisture are organometallic compounds

Organometallic compounds, also known as metal organic compounds, are compounds formed by the direct combination of carbon atoms of hydrocarbon groups and aromatic groups such as methyl, ethyl, propyl, butyl, and metal atoms.

A large packaging bottle, such as 500mL, will be decomposed and deteriorated due to the accelerated decomposition of oxygen or water vapor after repeated needle stick sampling

1.

Lithium in the organolithium compound directly forms a bond with carbon, such as n-BuLi, s-BuLi, t-BuLi, MeLi, PhLi, etc.

The most commonly used organolithium reagents are methyl lithium, butyl lithium, and phenyl lithium.

LDA and LiHMDS (including NaHMDS, KHMDS) are commonly used reagents in laboratories and are commercially available, but they are usually prepared by temporarily using butyl lithium to abstract protons from amines before use:

R ₂ NH+C ₂ H ₉ Li=R ₂ NLi+C ₄ H ₁₀

In the formula, R=(CH ₃ ) ₂ CH, (CH ₃ ) ₃ Si

Organolithium and Grignard reagents have many similarities.

Quenching treatment of waste organolithium compounds: Dissolve waste organopotassium compounds in 5-10 times the amount of anhydrous THF for dilution, add a small amount of dry ice to cool to -20～-10℃, and slowly add ethanol diluted with THF In, the reaction mole number of the quenching agent should be doubled.

To quench the excess organolithium compound after the reaction, the reaction solution can be naturally raised to room temperature, and then quenched by adding an aqueous solution with a suitable pH.

2.

Grignard reagent is a synonym for organomagnesium compounds

The method for destroying the discarded Grignard reagent and the excess Grignard reagent after the reaction can refer to the quenching method of the organolithium compound mentioned above

The method for destroying the waste organozinc reagent and the excess organozinc reagent after the reaction can refer to the quenching method of the organolithium compound mentioned above

4.

The compound formed by the α bond between aluminum and the carbon in the hydroxyl group has high reactivity.

For example, diisobutylaluminum hydride (DIBAL-H) ​​is a large sterically hindered derivative of lithium tetrahydroaluminum.
It is not suitable to use tetrahydrofuran as the solvent of DIBAL-H because the two react to form a coordination compound
.
Generally, it is stored in toluene or n-hexane solution at a concentration of 1.
0mol/L, and it reacts violently with water to generate oxygen
.

The quenching method of discarding DIBAL-H and excess DIBAL-H after the reaction can refer to lithium aluminum tetrahydrogen, especially the excess DIBAL-H after quenching the reaction, and full consideration should be given to preventing the occurrence of emulsification
.

The method for destroying other waste organoaluminum reagents including red aluminum (such as toluene solution) and excess organoaluminum reagent after the reaction is completed can refer to the quenching method of the organolithium compound mentioned above
.

5.
Organotin compounds

Organotin reagents commonly used in laboratories include dialkyl tin dihalides (such as dibutyl tin dichloride), trialkyl tin hydrogen (such as tri-n-butyl tin hydrogen), trialkyl tin halides (such as tri-n-butyl iodide) Tin), tetraalkyl tin (such as allyl tri-n-butyl tin), hexaalkyl tin (such as hexamethyl distannane) and the like
.
The method for destroying the discarded organotin reagent and the excess organotin reagent after the reaction can refer to the above-mentioned method for quenching of organolithium
.
For highly toxic or highly toxic organotin, you can add a saturated aqueous solution of KF or a Py-HF solution, stir vigorously for more than 30 minutes, and then perform post-processing and purification according to conventional methods
.

In short, the quenching method of the excess organomagnesium, organozinc, organoaluminum and organotin reagents after the reaction requires careful consideration
.
Alkali metal lithium, sodium or potassium can be quenched in acidic, neutral or alkaline water environment, and it is easy to operate.
The pH of the post-reaction treatment only needs to meet the requirements of the product; while magnesium, zinc, aluminum, and tin are at pH In larger cases, it may be emulsified, which is difficult to filter and affects the yield
.
Three points need to be considered: First, if the product has no special requirements for pH, the pH of the post-treatment should be controlled as weakly acidic as possible, such as quenching with a saturated aqueous solution of salts such as ammonium chloride; the second is magnesium, zinc, and zinc after water quenching.
The salt of aluminum and tin or the corresponding compound should be granular, which is easy to be removed by filtration, or dissolved in the aqueous phase and discarded by layers; third, it can be filtered through the mixture of KF and diatomaceous earth, or passed through a short silica gel column
.

Related links: Inorganic compounds that are flammable when wet