2.2- dimethyl-13-dioxepane

C8H12N2 99-98-9) see Methylthioninium chloride 4-ainino-l,3-dimethylbenzene (CgH N 95-6S-7) see Picotamide (5K,6S)-6-aniino-2,2-dimethyl-l,3-dioxepan-5-ol acetate (salt)... 

The bulk polymerization of 4-methyl-1,3-dioxepane at 0 °C yields 60% polymer. Further substitution decreases polymerizability as with 1,3-dioxolanes. 2,4-Dimethyl-1,3-dioxepane gives oligomers in limited yield, the 2,2-dimethyl-derivative dimerizes and the 4,4-dimethyl derivative does not polymerize at all53). 

The second general route to 1,3-dioxepanes (1) involves acid-catalyzed alcohol exchange of an acyclic acetal (6) with a 1,4-diol (transacetalization) <8iJOC298i>, as demonstrated by the synthesis of (12 X = C1, Br) by reaction of 2-halo-1,1-dialkoxyethane with 1,4-butanediol <79MI 911-01, 95JOC5729) or the preparation of (13) from benzil dimethyl acetal <90UKZlll6>. Transacetalization is preferred for the synthesis of 1,3-dioxepanes derived from ketones <61JOC4762> and the stereo-... 

Treatment of 2,2-dimethyl-1,3-dioxepane with carboxylic acids results in the formation of tetra-hydrofuran and acetone <6UOC4762>. Acid-catalyzed hydrolysis of methyl-substituted 2,2-diphenyl-... 

The synthesis of l,4-dioxepan-5-one was also achieved by Ti(0-/-Pr)4-catalyzed cyclization of methyl 3-(2-hydroxyethoxy)propionate (124) (Scheme 12) <87JPS(A)2629>. Dioxepanone (126) was formed by addition 2,5-dimethyl-2,5-hexadiene to methyleneperoxyketone (125) together with spiro derivative (127) <86JOC4479>. 

Z., and Wu, S.R. (1982) Free radical ring opening polymerization of 4,7-dimethyl-2-methylene- 1,3-dioxepane and 5,6-benzo-2 methylene-l,3-dioxepane. Macromolecules, 15, 711 (c) Liu,... 

The conformational properties of polyoxide chains have been further examined. The temperature coefficient of the dipole moments of poly(l,3-dioxolane), the dipole moment, and its temperature coefficient of the related polymers poly(l,3-dioxepane), poly(l,3-dic)xocane), and poly(l,3-dioxonane) have been measured and interpreted. The presence of even one C-C bond in such chains is sufficient to suppress conformational correlations between adjacent polar units (—CHj—O—CHj—0—CHj—). The pendant methyl groups of poly(3,3 -dimethyl oxetane) restrict the C—O bond conformations to the trans state, but the C—C bonds are relatively unhindered. The sensitivity of such conformational dependent properties as the molar Kerr constant, optical anisotropy, unperturbed dimensions, and dipole moments to possible irregular sequences in poly(l,3-dioxolane) have been calculated. ... 

RS,6SR)-2,2,5-Trimethyl-6-hydroxy-l,3-dioxepane containing a little coned. HCl stirred and distilled through a Vigreux column -> (2 RS,4SR)-2 -(2,2-dimethyl-l,3-dioxolan-4-yl)-l -propanol. Y 98%. W. J. Elliott and J. Fried, J. Org. Chem. ... 

Previously, the 2-methyl and the 2,2-dimethyl-l,3 dioxepane were investigated and only the monosubstituted derivative were found to undergo polymerization. The polymer had a regular structure as expected from the two equivalent acetal bonds in the monomer. Stereospecificity of this polymer is in principle possible, however, results concerning this have not been reported. 

Fig. 2.27 Infrared spectra of 4-methyl-1,3-dioxolane, 1,3-dioxolane, 3,3-dimethyl-m-dioxane, and 1,3-dioxepane.

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