Do you know what trifluoroacetaldehyde hydrate is?

　　Do you know what trifluoroacetaldehyde hydrate is?

The preparation of trifluoroacetaldehyde hydrate comprises the following steps:

(1) Preparing a mixture of chloral hydrate and benzene in a volume ratio of about 10.6 ~ 11.2, first removing the water in a water separator by azeotropic boiling of benzene;

(2) Add phosphite dropwise to a mixture of anhydrous trichloroacetaldehyde and benzene at a molar ratio of 11.0 ~ 12.0 between trichloroacetaldehyde and phosphite, and after the dropwise addition, remove the low boiling point material below 100;

(3) The residue is hydrolyzed and dehydrated with 5-30% by weight of concentrated sulfuric acid.

Trifluoroacetaldehyde hydrate is supposed to be a solid translucent crystal, but it does not keep well and absorbs moisture easily. It absorbs moisture and becomes a liquid, or a mixture of liquid and solid. However, chloral hydrate can also be used in liquid form or as a mixture of liquid and solid, and it does not fail. It is still used in the laboratory, but cannot be used if the prepared solution is in very strict proportions, as it contains a certain amount of water that cannot be taken accurately.

Trifluoroacetaldehyde hydrate, 2,2,2-trifluoroacetaldehyde, molecular formula C2HF30, CAS registry number 75-90-1, molecular weight 98.02, is a colourless gas with a boiling point of -18.8. Trifluoroacetaldehyde is unstable and easily polymerised. It is rapidly absorbed by water or ethanol to form stable trifluoroacetaldehyde hydrate or trifluoroacetaldehyde semi-ethanol. Trifluoroacetaldehyde and its derivatives are important reagents for trifluoromethylation and are widely used in synthetic resins, polymers, rubber, coatings, pharmaceuticals and pesticide industries.

Trifluoroacetaldehyde hydrate can be used to synthesise a variety of heterocyclic compounds containing trifluoromethyl groups, mainly for the production of new pharmaceuticals, pesticides and dyes. For example, trifluoroacetaldehyde hydrate can be used to prepare reactive lactones via the Reformasky reaction, and trifluoroacetaldehyde can be reacted with hydroxylamines followed by cycloaddition and rearrangement reactions to prepare various nitrogen compounds. Trifluoroacetaldehyde hydrate prepares fluorine- or trifluoromethyl-containing pyrazoles, tetrahydropyrans and oxazolidine heterocyclic compounds by cycloaddition reactions or amphiphilic reagent reactions; trifluoroacetaldehyde hydrate prepares trifluoromethyl olefins by the Wittig reaction, etc. These compounds are mainly used in the synthetic resin, rubber, coating, pharmaceutical and pesticide industries. Application areas will continue to be expanded in the future.

To prevent problems caused by polymerisation and autoxidation, liquid solutions of trifluoroacetaldehyde hydrate should be kept cool and used promptly after preparation. Trifluoroacetaldehyde is a carcinogen and direct contact is to be avoided. The reagents are hygroscopic and sensitive to air and moisture and need to be used in a fume hood.

The use of trifluoroacetaldehyde hydrate in organic chemistry is limited because it needs to be prepared now. Most of the reactions of trifluoroacetaldehyde are similar to those of acetaldehyde, mainly at the aldehyde group. Trifluoromethyl is an inert group in reactions and is often used to introduce a trifluoromethyl group in intermediates of complex products.