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  Home >> Chemistry Dictionary >>Apatite - Arndt Eistert Synthesis

Antistaic agents.
Compounds added to materials (particularly fibres, plastics) to reduce charge accumulation with resultant dust and dirt build up. E.g., metals, water and hygroscopic salts

Antithyroid drugs.
Substances which interfere with production of thyoxine by the thyroid gland e.g. perchlorate, thiocyanate, thiouracil, resorcinol.

Antitoxins.
Antibodies formed in blood to which bacterial toxins have been introduced

Apatite.
Ca5(PO4)3 F. A phosphate mineral having fluoride and phosphate anions. Used for the production of phosphorus and its compounds including superphosphates

Apo.
Prefix indicating a derived compound; thus apomorphine is derived from morphine

Apomorphine.
C17H17NO2. White crystals. It hydrochloride is prepared by heating morphine with hydrochloric acid under pressure. It is a potent emetic

Aprotic solvent.
A solvent which does not contain protons which can be released as H+.

Aqua regia.
A solution of conc. HNO3 with three to four times its volume of conc. HCI, so called because it will dissolve ‘noble’ metals, such at Pt and Au. Its strong oxidizing action is due to nitrosyl chloride (NOCI) and chlorine produced by interaction of the two acids

Ar. Argon.
Sometimes used as an abbreviation for an aromatic group

Aquation.
The process of replacement of other ligands by water, e.g., [Co(NH3)
4 (H2O)(NO3)]2+ ----> [Co(NH3)4(H,2O)2]+3
The process of complexing by water molecules

Aquo ions.
Hydrated metal ions in aqueous solution; also be applied to hydrated ions in complexes, e.g., [Co (H2O)6]2+

Arachidic acid.
N- eicosanic acid, C20H10O2, [CH2]18 COOH. M.p. 75°C. A fatty acid occurring as glycerides in peanut and other vegetable oils.

Aramide.
Kelver and Nomex fibres for heavy duty uses

Arc spectrum.
The emission spectrum obtained when a substance has been excited by application of an electric acid rather than an electric spark which gives a spark spectrum Arginase. The enzymes which decomposes arginine into ornithine and urea

Argol.
Crude potassium hydrogen tartate obtained from wine

Argon.
Symbol Ar. A monatomic noble gas present in air (0.93%) a.n. 18; r.a.m 39.948: d. 0.00;78g cm-3; m.p. – 189°C; b.p. 185.7°C. Argon is separated from liquid air by fractional distillation. It is slightly in water colourless, and has not smell. Its uses include inert atmosphere in welding and special-metal manufactures (Ti and Zr), and (when mixed with 20% nitrogen) in gas-filled electric-light bulbs. The element is inert and has no true compounds

Arndt-Eistert synthesis.
A procedure for converting a carboxylic acid to its next higher homologue, or to a derivative of a homologous acid e.g., ester or amide

      CH2N2
RCO2H ----------> RCOCI ---------->
      Et2O
  Ag+    
RCOCH2N2 ----------> RCH2CO2H  

Aromatic.
The property (aromaticity) which allows benzene to undergo Electrophilic substitution reaction, and also to account for its stability over open chain conjugated derivatives

Aromatic compounds
A organic compounds whose structure is based on that of benzene is called aromatic compound. Although benzene is unsaturated, it does not usually undergo addition reactions which are characteristic on the alkenes. Instead, the characteristic reaction of benzene is substitution or displacement of a hydrogen atom a evidence by the following reactions:
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