Lithium is an alkali metal widely used in industry. Lithium salts are indicated in the treatment of manic episodes of Bipolar Disorder. The use of lithium in psychiatry goes back to the mid-19th century. Early work, however, was soon forgotten, and John Cade is credited with reintroducing lithium to psychiatry for mania in 1949. Mogens Schou undertook a randomly controlled trial for mania in 1954, and in the course of that study became curious about lithium as a prophylactic for depressive illness. In 1970, the United States became the 50th country to admit lithium to the marketplace. The specific mechanisms by which lithium exerts its mood-stabilizing effects are not well understood. Lithium appears to preserve or increase the volume of brain structures involved in emotional regulation such as the prefrontal cortex, hippocampus and amygdala, possibly reflecting its neuroprotective effects. At a neuronal level, lithium reduces excitatory (dopamine and glutamate) but increases inhibitory (GABA) neurotransmission; however, these broad effects are underpinned by complex neurotransmitter systems that strive to achieve homeostasis by way of compensatory changes. For example, at an intracellular and molecular level, lithium targets second-messenger systems that further modulate neurotransmission. For instance, the effects of lithium on the adenyl cyclase and phospho-inositide pathways, as well as protein kinase C, may serve to dampen excessive excitatory neurotransmission. In addition to these many putative mechanisms, it has also been proposed that the neuroprotective effects of lithium are key to its therapeutic actions. In this regard, lithium has been shown to reduce the oxidative stress that occurs with multiple episodes of mania and depression. Further, it increases protective proteins such as brain-derived neurotrophic factor and B-cell lymphoma 2, and reduces apoptotic processes through inhibition of glycogen synthase kinase 3 and autophagy.

Acetic anhydride is an esterification agent for use in prepn. of modified food starch and for acetylation of monoglycerides. Acetic anhydride is a versatile reagent for acetylations, the introduction of acetyl groups to organic substrates. Acetic anhydride is the chemical compound with the formula (CH3CO)2O (commonly abbreviated Ac2O). Ac2O is mainly used for acetylations leading to commercially significant materials. Its largest application is for the conversion of cellulose to cellulose acetate, which is a component of photographic film and other coated materials. Similarly it is used in the production of aspirin, acetyl salicylic acid, which is prepared by the acetylation of salicylic acid. It is also used as a wood preservative via autoclave impregnation to make a longer lasting timber. Ac2O is also used in many industrial processes for the production of plastics, textiles, dyes, photochemical agents, perfumes, explosives and cigarette filters. Because of its use for the synthesis of heroin by the diacetylation of morphine, acetic anhydride (known as 'AA' in clandestine chemistry circles) is listed as a U.S. DEA List II Precursor, and restricted in many other countries.

Aniline is a toxic organic compound consisting of a phenyl group attached to an amino group. It is the prototypical aromatic amine. Aniline and its derivatives are very important for the synthesis of chemical products such as dyes, resins, and medicines. The main use of aniline is in the manufacture of precursors to polyurethane. Aniline is a carcinogen that is considered to induce tumors secondary to hemosiderosis as a consequence of methemoglobinemia. Aniline is classified as Group 3, not classifiable as to its carcinogenicity in humans (IARC, 480 1987b). Aniline occurs naturally in some foods (i.e., corn, grains, beans, and tea), but the larger source of exposure is in industrial settings. Lifetime permissible daily exposure (PDE) for aniline is 720 ug/day. Simple anilines such as aniline and monosubstituted anilines are known to disappear from the environment mainly via biodegradation.