An improved method for assessing relative nucleophilic substitution reactivities of polychlorinated benzenes

An existing substitution reaction method was improved as part of a system to measure the persistency of selected chemicals in the environment by evaluating their chemical reactivity. Hexachlorobenzene (HCB), pentachlorobenzene, 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene were selected as model compounds. Sodium methoxide in methanol was used as a nucleophile and found to be stable for at least 35 days after preparation. The substitution reaction system was modified so that nitrogen protection was not necessary to avoid oxidation and hydrolysis effects, which led to improved results. The reactivity of polychlorinated benzenes (PCBz), which substituted chlorine for methoxide according to a second-order rate constant, increased as the number of chlorine atoms on the benzene ring increased. HCB was selected as a standard for the k2 calculations of the substitution reactions. A normalized k2 (kN) was calculated as kN = kPCBz/kHCB. GC–MS analysis confirmed that the reactions were pure nucleophilic aromatic substitutions without side reactions.

NATURVETENSKAP Geovetenskap och miljövetenskap Miljövetenskap hsv//swe
NATURAL SCIENCES Earth and Related Environmental Sciences Environmental Sciences hsv//eng
Nucleophilic substitution
Polychlorinated benzenes
Nucleophile
Reactivity
Persistency
Chemical stability
Environmental chemistry
Miljökemi

Eriksson, JohanStockholms universitet,Institutionen för miljökemi,Percistency(Swepub:su)johaner (författare)
Granelli, LisaStockholms universitet,Institutionen för miljökemi,Percistency(Swepub:su)lgran (författare)
Bergman, ÅkeStockholms universitet,Institutionen för miljökemi(Swepub:su)alb (författare)
Stockholms universitetInstitutionen för miljökemi (creator_code:org_t)

Av författaren/redakt...: Qiu, Yanling; Eriksson, Johan; Granelli, Lisa; Bergman, Åke

Om ämnet

NATURVETENSKAP: NATURVETENSKAP; och Geovetenskap och ...; och Miljövetenskap

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