Perchlorobutatriene and Perchloro‐[4]radialene

Abstract

I3,=37Hz =3.7Hz Il3 =1.8 HZ z -2 3 i 5 6 80 70 60 50 -6 ippml Figure 1 . IH-NMR spectrum of 1,2-naphthalene oxide (in CC14; 60 MHz; tetramethylsilane as internal standard). No absorption beyond T = 6.2.1,2 Naphthalene oxide is obtained as a colorless crystalline compound that in the solid state rapidly rearrangessometimes with explosive violenceto a-naphthol. The presence of 1 ,Znaphthalene oxide follows unequivocally from the N M R spectrum reproduced in Figure 1. If the isomeric oxepin derivative ( 2 ) were present, then the signals corresponding to the protons H3 and H4 would appear at lower field strengths and, furthermore, the absorption due to H4 would be a singlet. The electronic spectrum of the oxide [maxima at 220 (E = 17600). 268 (8850). and 304 nm (1570) in dioxane] is remarkably similar to that of benzonorcaradiene 121. This finding rules out the possibility that 1,2-naphthalene oxide is in equilibrium with a significant concentration of the isomeric oxepin ( 2 ) . which is doubtless colored.Compound ( I ) is relatively stable in solution (ether). In the presence of catalytic amounts of a protic or a Lewis acid it spontaneously isomerizes to a-naphthol. Attempts to convert ( I ) into the known trans-l,2-dihydronaphthalene-l,2diol[71 have been unsuccessful. The fact that a number of authors have recently invoked 1,2-naphthalene oxide and other arene oxides as intermediates in enzymatic oxygenations of aromatic compounds 17981 seems a further justification for the publication of these results. Synthesis of I,2-Naphthalene Oxide a) 4-Bromo-I,2-epoxy-l.2,3,4-tetrahydronaphthalene (4)N-Bromosuccinimide (7.1 2 g, 40 mmole) and a,or'-azoisobutyrodinitrile (0.1 g) are added to a solution of 1,2-epoxy-1.2,3,4-tetrahydronaphthalene (3) (5.84 g. 40 mmole) in CC14 (75 ml). Once the reaction has'/ been started by quickly heating the mixture to boiling, no more heat has to be supplied. Succinimide and unreacted N-bromosuccinimide are filtered off and the filtrate is concentrated under vacuum until the bromide ( 4 ) begins to precipitate. On cooling to -lO°C, the main part of ( 4 ) crystallizes out in almost pure form; a further crop of ( 4 ) is obtained by working up the mother liquor. Recrystallization from ether/ethyl acetate (5:l) affords 2.1 g of (4) (23 % yield) having m.p. 94-95 OC (decomp.). b) l,2-Naphthalene Oxide ( I ) 1,5-Diazabicyclo[4.3.O]non-5-ene (400 mg, 3.2 mmole) is added dropwise,with stirring at 0 OC under an NZ atmosphere, to 4-bromo-1 ,bepoxy-l,2,3,4-tetrahydronaphthalene (4) (450 b.0mg. 2 mmole) in tetrahydrofuran (5 ml). The reaction mixture is stirred for 12 h at O°C and then allowed to stand for a further 12 h at this temperature. The tetrahydrofuran is evaporated off a t O°C under vacuum and the residue is treated first with 15 ml of pentane and then with 2 ml of water. The aqueous phase is extracted once again with 15 ml of pentane and the combined pentane solutions are washed three times with dilute KOH and dried over KzCO3. On cooling to -80°C, (1) crystallizes out as colorless needles...

Butatriene-Based Polymer Chemistry. 3. New Route to Substituted Poly(acetylene)s through the Base-Catalyzed Rearrangement of Poly(2-butyne-1,4-diyl)s

“…Introduction. The polymerization of simple butatrienes has long frustrated spectroscopists in their attempts to isolate and study the free monomeric molecule. − Carothers observed this phenomenon and obtained a patent on the potential use of butatriene as a reactive monomer, not understanding the nature of the polymer formed . Recently, we have been studying the structure and potential applications of butatrienes as monomers in addition polymerization. − In reviewing of the literature concerning 1,2,3-butatriene, there were reports that in some situations, the normally white solid formed from its polymerization would convert to a yellow, blue or even black material .…”

Synthesis and reactions of a tetraquinocyclobutane

“…3 The tetraquinocyclobutane structure is related to those of 4-radialenes, many of which can similarly by synthesized by dimerization of cumulenes. 4,5 In organic solvents 3 gives brilliant purple solutions which show complex electronic spectra in the visible and ultraviolet region (Figure 1). The spectrum of 3 is rather similar to that of the triquinocyclopropanes l,1 but the visible absorptions occur at higher energy for 3.…”

Tetraiodobutatriene: A New Cumulenic Carbon Iodide We thank J. Lauher for crystallography assistance, D. Salahub for use of the DeMon program at Stony Brook, and V. Malkin and M. Kaupp for helpful discussions. We also thank the Computing Center of the Slovak Academy of Sciences for computational resources. We acknowledge the National Science Foundation (CHE-9984937), the donors of the Petroleum Research Fund, administered by the American Chemical Society, and the Slovak Grant Agency VEGA (O.L.M., Grant No.

“…Perchlorobutatriene 6 is more stable (m.p. 59–60 °C), but like many cumulenes it dimerizes to form radialene 8 when heated 5. Perbromobutatriene 7 has not been reported, and compound 3 is, to the best of our knowledge, the first known iodine‐substituted cumulene of any sort 6…”