Eine Fragmentierung in der Adamantan‐Reihe

“…The introduction of an adamantyl moiety was found to induce great advancement of thermal property of the polymers because adamantane is a thermodynamically stable and highly symmetrical tricyclic hydrocarbon, which consists of fused chair-form cyclohexane rings with same structure as a diamond lattice. 13 For example, polymers from 1-adamantyl or 3,5-dimethyl-ladamantyl esters of methacrylate and acrylate have extremely high glass transition temperatures and decomposition temperature. 14 Other polymers bearing adamantyl moiety in the main or side chain have been also developed by some workers.…”

Section: Or Ormentioning

confidence: 99%

Synthesis and Characterization of Thermally Stable Polymers through Anionic Polymerization of tert-Alkyl Crotonates

Horie

Otsu

1991

Polym J

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ABSTRACT:Some alkyl crotonates bearing tert-alkyl groups, i.e., lert-butyl, tert-amyl, 1-adamantyl and 3,5-dimethyl-1-adamantyl crotonates were prepared and polymerized with sec-butyllithium as an anionic catalyst in toluene or THF. The resulting polymers were confirmed to consist of poly(substituted methylene) structure by IR and NMR spectroscopies. The polymers bearing adamantyl groups had more resistance to hydrolysis, whereas the tert-butyl and amyl esters were readily hydrolyzed. The introduction of the adamantyl groups also increased glass transition temperature and decomposition temperature of the polymer. It was revealed that the polymers bearing the tert-butyl and amyl esters decomposed via a two-step mechanism, resulting in the formation of poly(crotonic acid) accompanied with elimination of corresponding olefins from the ester groups, but the polymers containing adamantyl groups showed excellent thermal stability.

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“…X = Cl, Br, MeO, MeS, H 2 N, MeNH, Me 2 N.Fragmentation of some 1,3-disubstituted adamantanes through intermediate formation of stabilized 3-substituted 7-methylidenebicyclo[3.3.1]non-3-yl cations was reported in [1][2][3][4][5][6][7]; in the presence of water the latter were converted into 7-methylidenebicyclo-[3.3.1]non-3-one (Scheme 1). Presumably, in strongly basic medium such carbenium ions can be stabilized via elimination of proton with formation of double C=C bond.…”

mentioning

confidence: 98%

Reaction of dibromoadamantanes with glycols in the presence of sodium glycolate

Skomorokhov

Klimochkin

2011

Russ J Org Chem

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1,3-Dibromoadamantanes reacted with glycols in the presence of sodium glycolate to give novel unsaturated bicyclo[3.3.1]nonane derivatives and 1,3-disubstituted adamantanes. X = Cl, Br, MeO, MeS, H 2 N, MeNH, Me 2 N.Fragmentation of some 1,3-disubstituted adamantanes through intermediate formation of stabilized 3-substituted 7-methylidenebicyclo[3.3.1]non-3-yl cations was reported in [1][2][3][4][5][6][7]; in the presence of water the latter were converted into 7-methylidenebicyclo-[3.3.1]non-3-one (Scheme 1). Presumably, in strongly basic medium such carbenium ions can be stabilized via elimination of proton with formation of double C=C bond.We previously found [8] that 1,3-dibromoadamantane (I) in ethylene glycol at 200°C in the presence of a strong base is converted into a mixture of 2-(7-methylidenebicyclo[3.3.1]non-2-en-3-yloxy)ethanol (II) and 7-methylidenespiro[bicyclo[3.3.1]nonane-3,2′-[1,3]dioxolane] (III). More detailed analysis of the product mixture allowed us to reveal 10-12% of 2,2′-(adamantane-1,3-diybisoxy)diethanol (IV). 1,3-Dibromo-5,7-dimethyladamantane (VI) reacted in a similar way (Scheme 2).The products were isolated from the reaction mixture by selective extraction and subsequent vacuum distillation or recrystallization from appropriate solvent.As might be expected [9], vinyl ether II upon distillation or heating to 100°C, as well as during chromatography on silica gel, is quantitatively converted into spiro dioxolane III. Protection of the hydroxy group by esterification made it possible to isolate by vacuum distillation 2-(7-methylidenebicyclo-[3.3.1]non-2-en-3-yloxy)ethyl acetate (Va); the corresponding p-nitrobenzoate Vb was isolated by fractional recrystallization from methanol. Compounds IVa and IXa were isolated and characterized as p-nitrobenzoates IVb and IXb (Scheme 2).The structure of the products obtained by reactions of 1,3-dibromoadamantanes I and VI with ethylene glycol suggests the following reaction mechanism. 1,3-Dibromoadamantane I or VI in polar medium gives rise to 3-bromoadamantan-1-yl cation which takes up ethylene glycol molecule to produce intermediate A. Heterolytic dissociation of the C-Br bond in A generates cation B which undergoes Grob fragmentation with formation of carbenium ion C. The latter can be stabilized according to two pathways. Intramolecular proton abstraction from the α-carbon

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Eine Fragmentierung in der Adamantan‐Reihe

Cited by 11 publications

References 3 publications

Adamantane: Consequences of the Diamondoid Structure

Adamantane: Consequences of the Diamondoid Structure

Synthesis and Characterization of Thermally Stable Polymers through Anionic Polymerization of tert-Alkyl Crotonates

Reaction of dibromoadamantanes with glycols in the presence of sodium glycolate

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