compound (kom´pownd)

1. In chemistry, a substance formed by the covalent or electrostatic union of two or more elements, generally differing entirely in physical characteristics from any of its components. 2. In pharmacy, denoting a preparation containing several ingredients. For c.'s not listed here, see the specific chemical or pharmaceutical names. [thru O. Fr., fr. L. compono]
acetone c. ketone body
acyclic c. an organic c. in which the chain does not form a ring.aliphatic c., open chain c;
addition c. 1. strictly, a complex of two or more complete molecules in which each preserves its fundamental structure and no covalent bonds are made or broken (e.g., hydrates of salts, adducts); 2. loosely, association of acids with basic organic c.'s (e.g., amines with HCl); 3. more loosely, addition of two molecules without loss of any atom, but forming new covalent bonds (e.g., CH2=CH2 + Br2 -> BrCH2-CH2Br).
alicyclic c.'s See cyclic c.
aliphatic c. acyclic c
APC c. an analgesic tablet drug combination containing aspirin, phenacetin and caffeine. Very widely used in the 1940's through 1960's; original constituents of popular over-the-counter pain remedies. Use currently much diminished due to concerns about potential renal injury due to the phenacetin.
aromatic c. See cyclic c.
carbamino c. any carbamic acid derivative formed by the combination of carbon dioxide with a free amino group to form an N-carboxy group, -NH-COOH, as in hemoglobin forming carbaminohemoglobin.
carbocyclic c. See cyclic c.
closed chain c. cyclic c
condensation c. a c. resulting from the combination of two or more simple substances, with the splitting off of some other substance, such as alcohol or water; e.g., a peptide. Cf. conjugated c.
conjugated c. a c. formed by the union of two c.'s (as by the elimination of water between an alcohol and an organic acid to form an ester) and easily converted to the original c.'s (hydrolysis). See also conjugation (4). Cf. condensation c.
cyclic c. any c. in which the constituent atoms, or any part of them, form a ring. Used mainly in organic chemistry where: 1) numerous c.'s contain rings of carbon atoms (carbocyclic c.'s) or carbon atoms plus one or more atoms of other types (heterocyclic c.'s), usually nitrogen, oxygen, or sulfur; 2) where the atoms in the ring are all of the same element (homocyclic or isocyclic c.); 3) where the ring is saturated or contains nonconjugated double bonds (alicyclic c.), the c. is similar in properties to the corresponding acyclic c. (e.g., cyclohexane resembles hexane); 4) where the ring contains conjugated double bonds in a closed loop in which there are 4n + 2 (where n is an integer) delocalized pi electrons (Hückel's rule) (aromatic c.; e.g., benzene, pyridine), it is more stable than the corresponding saturated ring and exhibits unusual chemical properties characteristic of itself and not of other types of rings or of acyclic c.'s. These aromatic c.'s have the ability to sustain an induced ring current.closed chain c., ring c;
genetic c. compound heterozygote
glycosyl c. the c. formed between a sugar and another organic substance in which the OH of the reducing (hemiacetal) group of the former is removed; e.g., the natural nucleosides, in which a heterocyclic N becomes linked directly to the C-1 of ribose (or deoxyribose) to yield ribosyl compounds. Cf. glycoside.
heterocyclic c. See cyclic c.
high energy c.'s classically, a group of phosphoric esters whose hydrolysis takes place with a standard free energy change of -5 to -15 kcal/mol (or, -20 to -63 kJ/mol) (in contrast to -1 to -4 kcal/mol or, -4 to -17 kJ/mol) for simple phosphoric esters like glucose 6-phosphate or a-glycerophosphates), thus being capable of driving energy-consuming reactions in living cells or reconstituted cell-free systems; adenosine 5´-triphosphate, with respect to the beta- and gamma-phosphates, is the best known and is regarded as the immediate energy source for most metabolic syntheses. The general types are acid anhydrides, phosphoric esters of enols, phosphamic acid (R-NH-PO3H2) derivatives, acyl thioesters (e.g., of coenzyme A), sulfonium c.'s (R3-S+), and aminoacyl esters of ribosyl moieties. See also high energy phosphates, under phosphate.
homocyclic c. See cyclic c.
impression c. modeling plastic
inclusion c. the mechanical trapping of small molecules within spaces between other molecules; e.g., the inclusion of iodine molecules by starch molecules to form the well-known red-to-black "addition c."
inorganic c. a c. in which the atoms or radicals consist of elements other than carbon and are typically held together by electrostatic forces rather than by covalent bonds; often are capable of dissociation into ions in polar solvents (e.g., H2O). Cf. organic c.
isocyclic c. See cyclic c.
Kendall's c.'s a group of corticosteroids. Kendall's compound A (11-dehydrocorticosterone); Kendall's compound B (corticosterone); Kendall's compound E (cortisone); Kendall's compound F (cortisol).Kendall's substance;
meso c.'s c.'s containing more than one asymmetric carbon atom, with configurations about them so balanced that the molecule as a whole possesses a plane of symmetry, although the individual carbon atoms do not; such compounds are not optically active; e.g., ribitol, mucic acid, meso-inositol, meso-cystine.
methonium c.'s agents that block impulses in ganglia (e.g., hexamethonium) and are used in arterial hypertension; also used for neuromusclar paralysis in surgery (e.g., decamethonium).
modeling c. modeling plastic
nonpolar c. a c. composed of molecules that possess a symmetrical distribution of charge, so that no positive or negative poles exist, and that are not ionizable in solution; e.g., hydrocarbons. See also organic c.
open chain c. acyclic c
organic c. a c. composed of atoms (some of which are carbon) held together by covalent (shared electron) bonds. Cf. inorganic c.
polar c. a c. in which the electric charge is not symmetrically distributed, so that there is a separation of charge or partial charge and formation of definite positive and negative poles; e.g., H2O. See also inorganic c.
Reichstein's c. Reichstein's substance
ring c. cyclic c
Wintersteiner c. F cortisone


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