Nucleophilic reactions of hexafluorob enzene and related polyfiuorobenzenes were studied in detail. R eaction of hex a fluorobenzc nc with hydroxides, alco holates, aqueous amines, and organolithium co mpounds led to the substitution of one 01' more fluorine atoms. The stru ctures of the products were determined, using near infra red a nd nuclear m agnetic resonance spectra. Fluorine is replaced more readily than chlorin e, bromine, iodine, or other groups. I n the ma jo rity of the products in which two of the fluorin es in hexafluorobenzene we re replaced, t he substituting groups were p a ra to eac h other. However, depe nding on the reagents other orientation effects were noted . The reaction mechanis ms we re a fun ction of reagents a nd co nditions. The mo t prcvalent mecha ni sm is presuma bly the di splace me nt of a fluoride anion by another anion, probably via the fo rmation of transition co mplexes of difl'erent lifetimes. Howeve r, simple ionization 0 1' attack by neutral species may occ ur under some co nditions. The diazotization a nd oxidation of pentafluoroan il ine were also inv estigated.

In a comprehen s ive stud y of th e cycli c, int er intramo lec ular mec hani s m in diene polymerization, a ll of th e co mpl e te ly Au or ina ted di e nes fro m C , to C. have been pre pared with a hi gh degree of purity. Al so pre pared were 4-c hl oro perAu oro-l ,6-hep tadie ne a nd pe rAu oro-l ,ll-dodeca di e ne, th e lall e r inadvf· rt e ntl y. Th e s uc(,ess ful s ynth eses in vo lved. in mos t ca~es. a te lom e rizat ion whi c h uti lized. as th e s ta rtin g m a te ri a l, 1,. l C I, CF,C FCI , or CF ,C F , . From these te lome rs, not only th e di e nes but many ne w interm e diat e co mpound s were pre pared ; th e y we re th e n purifi ed and c ha racterized. Th e c he mi s try of th ese co mpo und s, es pec ially that relat in g to th e ir po lyme ri za tio n, is bri e Ay di sc ussed.Key word s: Cyc li c int e r-intram olec ul a r mec han is m ; di e ne polym e rization; f1uorodi e nes; i nter~ediates; polym e riza ti on ; purity; sy nth es is; te lomerizat ion.

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l)uilfiin<; materials, components, systems, and whole structures. The Series presents research results, test methods, and performance criteria related to the structural and environmental functions and the durability and safety characteristics of building elements and systems.These publications, similar in style and content to the NBS Building Materials and Structures Reports The properties of impregnated and unimpregnated specimens were investigated by: scanning electron microscopy; porosity determinations; fracture mechanics studies; and strength determinations. The polymer impregnated mortars had compressive and fiexural strengths and fracture toughnesses which were substantially higher than unimpregnated mortars.