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anhydride

anhydride (ănhī´drīd, –drĬd) [Gr.,=without water], chemical compound formed by removing water, H2O, from another compound; the anhydride can also react with water to form the original compound. An acid anhydride reacts with water to form an acid; e.g., sulfur trioxide, SO3, reacts with water to form sulfuric acid, H2SO4. A basic anhydride reacts with water to form a base; e.g., calcium oxide, CaO, reacts with water to form calcium hydroxide, Ca(OH)2. Anhydrides of organic acids have many uses. They react with alcohols to form esters; e.g., acetic anhydride, (CH3CO)2O, reacts with ethanol, C2H5OH, to form ethyl acetate, CH3COOC2H5, a useful solvent. They also react with ammonia and primary or secondary amines to form amides. Other important acid anhydrides include maleic anhydride and phthalic anhydride.

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creatinine

creatinine Formed non‐enzymically from creatine (chemically the anhydride of creatine). Urinary excretion of creatinine is relatively constant from day to day, and reflects mainly the amount of muscle tissue in the body. Therefore the amounts of various components of urine are often expressed relative to creatinine.

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"creatinine." A Dictionary of Food and Nutrition. . Retrieved June 25, 2017 from Encyclopedia.com: http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/creatinine