cyclooctatetraene [ORG CHEM] C8H8A cyclic olefin with alternate double bonds; highly reactive; rearranges to styrene. {¦sı¯⭈klo¯a¨k⭈təte⭈trəe¯n }
cycloolefinSee cycloalkene. {¦sı¯⭈klo¯o¯⭈lə⭈fən } cycloparaffinSee alicyclic. {¦sı¯⭈klo¯par⭈ə⭈fən }
1,3-cyclopentadiene [ORG CHEM] C5H6A colorless liquid boiling at 41.5⬚C; used to make resins. {¦wən ¦thre¯ ¦sı¯⭈klo¯pen⭈tədı¯e¯n }
cyclopentadienyl anion [ORG CHEM] C5H5⫺ A radical formed from cyclopentadiene.
{¦sı¯⭈klo¯pen⭈tədı¯e⭈nil anı¯⭈ən }
cyclopentane [ORG CHEM] C5H10A cyclic hydrocarbon that is a colorless liquid; present in crude petroleum, it is converted during refining to aromatics which improve antiknock and combustion properties of gasoline. {¦sı¯⭈klo¯penta¯n }
cyclopentanoid [ORG CHEM] A compound whose key structural unit consists of five carbon atoms arranged in a ring. {¦sı¯⭈klo¯pen⭈təno˙id }
cyclopentanol [ORG CHEM] C5H9OH A colorless liquid boiling at 139⬚C; used as a solvent for perfumes and pharmaceuticals. Also known as cyclopentyl alcohol.
{¦sı¯⭈klo¯pen⭈təno˙l }
cyclopentanone [ORG CHEM] C5H8O A saturated monoketone; a colorless liquid boiling at 130⬚C; used as an intermediate in pharmaceutical preparation. { ¦sı¯⭈klo¯pen⭈
təno¯n }
cyclopentene [ORG CHEM] (CH2)3CHCH A colorless liquid boiling at 45⬚C; used as a chemical intermediate in petroleum chemistry. {¦sı¯⭈klo¯pente¯n }
cyclopentenylundecylic acid See hydnocarpic acid. {¦sı¯⭈klo¯pen⭈tənilən⭈dəsil⭈ik
as⭈əd }
cyclopentyl alcoholSee cyclopentanol. {¦sı¯⭈klo¯pent⭈əl al⭈kəho˙l }
cyclophane [ORG CHEM] A molecule composed of an aromatic ring (most frequently a benzene ring) and an aliphatic unit which forms a bridge between two (or more) positions of the aromatic ring. {sı¯⭈kləfa¯n }
cyclopropane [ORG CHEM] C3H6A colorless gas, insoluble in water; used as an anesthe-tic. {¦sı¯⭈klo¯pro¯pa¯n }
cyclopropanoid [ORG CHEM] A compound whose key structural unit consists of three carbon atoms arranged in a ring. {¦sı¯⭈klo¯pro¯⭈pəno˙id }
cycloreversionSee cycloelimination. {sı¯⭈klə⭈river⭈zhən }
cyclotrimethylenetrinitramineSee cyclonite. {¦sı¯⭈klo¯trı¯¦meth⭈əle¯ntrı¯nı¯⭈trəme¯n } cyhexatin [ORG CHEM] C18H34OSn A whitish solid, insoluble in water; used as a miticide
to control plant-feeding mites. { sı¯hek⭈sə⭈tən }
cymene [ORG CHEM] Any of the isomeric hydrocarbons metacymene, paracymene, and orthocymene; paracymene is a liquid that is colorless, has a pleasant odor, and is made from oil of cumin or oil of wild thyme. {sı¯me¯n }
cystamine [ORG CHEM] (CH2)6N4A white, crystalline powder, melting at 280⬚C; used to make synthetic resins. Also known as aminiform; crystogen; cystamine methena-mine; hexamethylene tetramethena-mine; urotropin. {sis⭈təme¯n }
cystamine methenamineSee cystamine. {sis⭈təme¯n məthen⭈əme¯n }
Czerny-Turner spectrograph [SPECT] A spectrograph used chiefly in laboratory work, which has a plane reflection grating and spherical reflectors for the collimator and camera. {¦cher⭈ne¯¦tərn⭈ər spek⭈trəgraf }
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D
2,4-DSee 2,4-dichlorophenoxyacetic acid.
dalapon [ORG CHEM] Generic name for 2,2-dichloropropionic acid; a liquid with a boil-ing point of 185–190⬚C at 760 mmHg; soluble in water, alcohol, and ether; used as a herbicide. {dal⭈əpa¨n }
Dalton’s atomic theory [CHEM] Theory forming the basis of accepted modern atomic theory, according to which matter is made of particles called atoms, reactions must take place between atoms or groups of atoms, and atoms of the same element are all alike but differ from atoms of another element. {do˙l⭈tənz əta¨m⭈ik the¯⭈ə⭈re¯ } Daniell cell [PHYS CHEM] A primary cell with a constant electromotive force of 1.1 volts, having a copper electrode in a copper sulfate solution and a zinc electrode in dilute sulfuric acid or zinc sulfate, the solutions separated by a porous partition or by gravity. {dan⭈yəl sel }
dansyl chloride [ORG CHEM] (CH3)2NC10H6SO2Cl A reagent for fluorescent labeling of amines, amino acids, proteins, and phenols. {dans⭈əl klo˙rı¯d }
DAPSee diallyl phthalate.
dark-line spectrum [SPECT] The absorption spectrum that results when white light passes through a substance, consisting of dark lines against a bright background.
{da¨rk ¦lı¯n spek⭈trəm }
Darzen’s procedure [ORG CHEM] Preparation of alkyl halides by refluxing a molecule of an alcohol with a molecule of thionyl chloride in the presence of a molecule of pyridine. {da¨r⭈zənz prəse¯⭈jər }
Darzen’s reaction [ORG CHEM] Condensation of aldehydes and ketones with ␣-haloesters to produce glycidic esters. {da¨r⭈zənz re¯ak⭈shən }
dative bondSee coordinate valence. {¦da¯d⭈iv ba¨nd }
dazomet [ORG CHEM] C5H10N2S2A white, crystalline compound that decomposes at 100⬚C; used as a herbicide and nematicide for soil fungi and nematodes, weeds, and soil insects. Also known as tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-6-thione.
{da¯⭈ zə⭈mət } DbSee dubnium.
DBCPSee dibromochloropropane.
d-block element [CHEM] A transition element occupying the first, second, and third long periods of the periodic table. {de¯ bla¨k el⭈ə⭈mənt }
DCBSee 1,4-dichlorobutane.
DCCSee dicyclohexylcarbodiimide.
DCCISee dicyclohexylcarbodiimide.
DCMOSee carboxin.
DCNASee 2,6-dichloro-4-nitroaniline.
DCPASee dimethyl-2,3,5,6-tetrachloroterephthalate.
DDDSee 2,2-bis(para-chlorophenyl)-1,1-dichloroethane.
DDT [ORG CHEM] Common name for an insecticide; melting point 108.5⬚C, insoluble in water, very soluble in ethanol and acetone, colorless, and odorless; especially useful against agricultural pests, flies, lice, and mosquitoes. Also known as dichlorodiphenyltrichloroethane.
DDTASee derivative differential thermal analysis.
DDVPSee dichlorvos.
DEA
DEASee diethanolamine.
deacetylation [ORG CHEM] The removal of an acetyl group from a molecule. {de¯⭈
əse¯d⭈əla¯⭈shən }
deacidification [CHEM]1.Removal of acid. 2.A process for reducing acidity. {de¯⭈
əsid⭈ə⭈fəka¯⭈shən }
deactivation [CHEM]1.Rendering inactive, as of a catalyst. 2.Loss of radioactivity.
{ de¯ak⭈təva¯⭈shən }
deacylation [ORG CHEM] Removal of an acyl group from a compound. { de¯as⭈əla¯⭈
shən }
DEAE-celluloseSee diethylaminoethyl cellulose. {de¯e¯a¯e¯ sel⭈yəlo¯s }
dealkalization [CHEM] 1.Removal of alkali. 2.Reduction of alkalinity, as in the process of neutralization. { de¯al⭈kə⭈ləza¯⭈shən }
dealkylate [CHEM] To remove alkyl groups from a compound. { de¯al⭈kəla¯t } dealuminization [CHEM] Removal of aluminum. {de¯⭈əlu¨⭈mə⭈nəza¯⭈shən } deamidation [ORG CHEM] Removal of the amido group from a molecule. { de¯am⭈
əda¯⭈shən }
deamination [ORG CHEM] Removal of an amino group from a molecule. { de¯am⭈
əna¯⭈shən }
deashing [CHEM] A form of deionization in which inorganic salts are removed from solution by the adsorption of both the anions and cations by ion-exchange resins.
{ de¯ash⭈iŋ }
debenzylation [ORG CHEM] Removal from a molecule of the benzyl group. { de¯ben⭈
zəla¯⭈shən }
de Brun-van Eckstein rearrangement [ORG CHEM] The isomerization of an aldose or ketose when mixed with aqueous calcium hydroxide to form a mixture of various monosaccharides and unfermented ketoses; used to prepare certain ketoses.
{ də¦bru˙n v anekshtı¯n re¯⭈əra¯nj⭈mənt }
Debye-Falkenhagen effect [PHYS CHEM] The increase in the conductance of an electro-lytic solution when the applied voltage has a very high frequency. { də¦bı¯ fa¨l⭈
kənha¨g⭈ən ifekt }
Debye forceSee induction force. { dəbı¯ fo˙rs }
Debye-Hu¨ckel theory [PHYS CHEM] A theory of the behavior of strong electrolytes, according to which each ion is surrounded by an ionic atmosphere of charges of the opposite sign whose behavior retards the movement of ions when a current is passed through the medium. { də¦bı¯ hik⭈əl the¯⭈ə⭈re¯ }
Debye relaxation time [PHYS CHEM] According to the Debye-Hu¨ckel theory, the time required for the ionic atmosphere of a charge to reach equilibrium in a current-carrying electrolyte, during which time the motion of the charge is retarded. { dəbı¯
re¯laksa¯⭈shən tı¯m }
decaborane (14) [INORG CHEM] B10H14A binary compound of boron and hydrogen that is relatively stable at room temperature; melting point 99.5⬚C, boiling point 213⬚C.
{¦dek⭈ə¦bo˙ra¯n fo¯r¦te¯n }
decahydrate [CHEM] A compound that has 10 water molecules. {dek⭈əhı¯dra¯t } decahydronaphthalene [ORG CHEM] C10H18A liquid hydrocarbon, used in some paints
and lacquers as a solvent. {dek⭈əhı¯⭈dro¯naf⭈thəle¯n }
decalcification [CHEM] Loss or removal of calcium or calcium compounds from a calcified material such as bone or soil. { de¯kal⭈sə⭈fəka¯⭈shən }
decane [ORG CHEM] C10H22Any of several saturated aliphatic hydrocarbons, especially CH3(CH2)8CH3. {de¯ka¯n }
decanolSee decyl alcohol. {dek⭈əno˙l }
decarbonize [CHEM] To remove carbon by chemical means. { de¯ka¨r⭈bənı¯z } decarboxylate [ORG CHEM] To remove the carboxyl radical, especially from amino acids
and protein. {de¯⭈ka¨rba¨k⭈səla¯t }
decavanadate [INORG CHEM] A deep-orange polyvanadate (V10O286⫺), composed of 10 fused VO6octahedra. {de¯⭈kə van⭈əda¯t }
dechlorination [CHEM] Removal of chlorine from a substance. { de¯klo˙r⭈əna¯⭈shən }