ЛИТИЙ перхлорат

Описание

Lithium perchlorate,is an oxysalt that is a colorless, deliquescent crystal. Oxysalt “per-ate” compounds are loaded with excess oxygen and will readily give it up in a reaction. Lithium perchlorate is a powerful oxidizing agent. It has more available oxygen than does liquid oxygen on a volume basis. Lithium perchlorate has a specific gravity of 2.429, which is heavier than water, and is water soluble. It is a dangerous fire and explosion risk in contact with organic materials and is an irritant to skin and mucous membranes. The primary use of lithium perchlorate is as a solid rocket propellant. Chlorates are strong oxidizing agents. When heated, they give up oxygen readily. Contact with organic or other combustible materials may cause spontaneous combustion or explosion. They are incompatible with ammonium salts, acids, metal powders, sulfur, and finely divided organic or combustible substances.

Химические свойства

White crystalline powder

Использование

The big advantage of lithium perchlorate is its high density and oxygen availability for combustion. A quite interesting methodology involves the use of lithium perchlorate anhydrides complexes in the acylation of activated aromatic compounds.Lithium perchlorate is frequently utilized as promoter to accelerate the acylation process and to increase the yield in the reaction catalyzed by metal triflates.However, lithium perchlorate itself can act as a very efficient catalyst in the acylation of variously substituted methoxy? and methylbenzenes with AAN affording the aryl ketones in 65%–99% yield. The exceptional activation is ascribed to the formation of a complex with a strong electrophilic character between lithium perchlorate and AAN in neat AAN. The observed para?regioselectivity can be interpreted in terms of the high steric requirement of the lithium perchlorate– AAN complex. A further important feature of this process is the possibility of quantitatively recovering and reusing the catalyst after activation. It must be underlined, however, that lithium perchlorate is an oxidizing compound and can undergo devastating explosions; consequently, it must be handled with maximum care.

Общее описание

Lithium perchlorate (LiClO₄) is a colorless lithium salt. Upon crystallization from its aqueous solution, it affords lithium perchlorate trihydrate (LiClO₄.3H₂O). It can be synthesized by reacting lithium chloride with perchloric acid.

Материалы батареи

Lithium perchlorate (LiClO4) is sufficiently soluble (beyond 1Min organic solvents, e.g., EC/DMC) and forms electrolyte solutions with good conductivity (about 9 mS·cm?1 in EC/DMC at ambient temperature). In organic solvents LiClO4 forms thicker solid electrolyte interface (SEI) layers than LiPF6 or LiBF4, but they are less resistive. This fact is attributed to the highly resistive LiF on the surface which is formed by hydrogen fluoride (HF) generated by hydrolysis of fluorine-containing anions, for example, LiBF4 and LiPF6, with traces of moisture and the existing SEI layer [62, 63]. Furthermore, it has a high anodic stability of up to 5.1 V on LiMn2O4 in EC/DMC and is less hygroscopic than LiPF6. Despite its many advantages, the high oxidation state of chlorine (VII) in ClO4 ? results in problems. LiClO4 solutions are thermally unstable and show explosion risks, especially in ethers.

Методы очистки

Crystallise it from water or 50% aqueous MeOH. It is rendered anhydrous by heating the trihydrate at 170-180o in an air oven. It can then be recrystallised twice from acetonitrile and again dried under vacuum [Mohammad & Kosower J Am Chem Soc 93 2713 1971]. SKIN IRRITANT.