Tetracyclo[3.3.1.1[sup 3,7].0[sup 1,3]]decane, also called 1,3-dehydroadamantane or DHA, was heated at 195° C in n-octane and cumene solutions, with and without added 2,6-di-t-butyl-p-cresol, hereafter referred to as cresol. The kinetic order of the decomposition of DHA at 0.015 to 0.15 M solutions varied from 1.7 in octane to 1.5 in cumene and was 1.0 in solutions containing cresol. The overall rate of reaction increased on changing solvent systems in the order octane, cumene, octane with cresol and cumene with cresol. The first order rate constants for the reactions in the octane and cumene solutions containing cresol wereu7.9 x 10⁻³ min ⁻¹ and 14.3 x 10"3 min-1 respectively. By comparison, the rate constants from a first order calculation using the data for the reactions in octane and cumene were 2.2 x 10⁻³ min ⁻¹ and 4.6 x 10⁻³ min ⁻¹ respectively. The products of reaction in octane solution were l,l'-biadamantane, ca. 70%, adamantane, ca. 3%, polyadamantanes, ca_. 15%, and three unidentified liquids, ca. 10% total. With the addition of the cresol, the products were l,l'-biadamantane, ca. 70%, adamantane, ca. 17%, and the three unidentified products, ca. .10% total, with no polyadamantanes observed. In cumene solution, the products of reaction were 1,1'-biadamantane, 29%, 2-(1-adamantyl)~2-phenylpropane, 20%, 2,3-dimethyl-2,3-di phenyl butane, 37%, adamantane, 8%„ and an unidentified product, 5%. The presence of dimeric and polymeric products and the change in rate on addition of cresol suggest a radical chain mechanism. The initiation step was considered to be most likely the attack of the vibrationally excited DHA molecule on the solvent, the dissolved cresol if present, or another DHA molecule. Some brief, unsuccessful attempts were made to prepare DHA from 1-bromoadamantane using n-butyllithium and using KOH in methanol and from 1,3-dibromoadamantane using n-butyl Grignard reagent. No DHA was observed. The unusual bonding present in DHA results in a UV spectrum having four local maxima at 282-285 nm., 274 nm., 265 nm., and 254-257 nm., with the maximum at 274 nm., e = 13. / Science, Faculty of / Chemistry, Department of / Graduate

Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 203-210).

The synthesis of a new type of highly strained cyclopropyl group between the two remaining bridgehead positions in 1,3-dimethyl- adamantane was accomplished by an internal coupling reaction involving the removal of two bromines with sodium-potassium alloy in ether. The product, 5,7-dimethyltetracyclo [3.3.1.1⁵⁷.0 ¹³] decane, commonly named 3,5-dimethyl-l,3-dehydroadamantane (DMDHA), formed a polymer on heating the pure material to a temperature above 90°C. The polymer's properties were studied by X-ray analysis and differential scanning calorimetry. The previously reported parent compound to DHDMA, tetracyclo-5 7 13 [3.3.1.1⁵⁷.0 ¹³] decane, commonly named 1,3-dehydroadamantane (DHA), was synthesized and studied to determine the properties of the cyclopropyl bond between the bridgehead carbons. Reactions with several stable free radicals and other known reagents with affinities for radicals indicated a very high degree of radical character present at the bridgehead positions. From kinetic studies of the reaction of DHA with molecular oxygen at approximately 1 atmosphere and 22°C, first order kinetic plots were obtained which yielded the rate constants of k = 15.0 x 10⁻⁵ sec⁻¹ in octane and 32.8 x 10⁻⁵ sec⁻¹ in xylene. Oxygen was absorbed to an extent slightly greater than one mole per mole of DHA. The reaction was without ambiguity shown to be of radical nature through the use of several free radical inhibitors to retard the reaction rate. The initiation mechanism of the DHA-oxygen copolymerization could not be determined with certainty. The spontaneous reaction was either initiated by oxygen radicals attacking the highly strained, highly p-orbital-charactered carbon atom from its unprotected back side or else by the internal bond of the cyclopropyl group spontaneously ring opening to form an adamantane diradical. In the latter case the radical formed would sometimes capture an oxygen before the equilibrium shifted back to the closed form. All that is known for certainty is that the 1,3-carbon bond in DHA is very highly strained and is either in equilibrium between an open and a closed form or else is at least very radical-like in nature. / Science, Faculty of / Chemistry, Department of / Graduate

No description available.

Thèse doctorat : Génie des matériaux : Ecully, Ecole centrale de Lyon : 2008. / 174 références.

Thèse doctorat : Génie des matériaux : Ecully, Ecole centrale de Lyon : 2008. / Titre provenant de l'écran-titre. 174 références.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (MSc)--University of Stellenbosch, 2005. / Bibliography. Also available via the Internet.

Les polymères synthétiques tels que les dendrons ou les dendrimères possèdent des propriétés structurales intéressantes. Leur monodispersité et leur synthèse étape par étape permet de contrôler et de caractériser totalement leur structure. De plus, la multivalence offre aux vecteurs une meilleure affinité d’interactions entre plusieurs copies d’un ligand lié au dendron/dendrimère et le récepteur désiré en comparaison au ligand seul. L’adamantane est une molécule rigide et stable dont plusieurs dérivés ont été commercialisés pour des applications thérapeutiques, principalement comme agents antiviraux. De plus, il est possible de le fonctionnaliser sur 4 positions symétriques via des synthèses organiques. Sa conformation 3D permet d’amoindrir les encombrements stériques entre les groupements fonctionnels. Nous avons alors choisi de combiner les propriétés de l’adamantane et des dendrons afin de construire de nouveaux vecteurs synthétiques. Leurs synthèses s’effectuent avec de hauts rendements et chaque nouveau composé a été totalement caractérisé par les différentes techniques d’analyses chimiques et structurales. Les dendrons à base d’adamantane polycationiques non cytotoxiques ont révélé une forte pénétration cellulaire permettant de mieux comprendre les mécanismes d’internalisation des dendrons. Ils ont également été évalués pour la formation de complexes avec un plasmide d’ADN. Des modifications sur leurs structures ont amélioré leur capacité à interagir avec l’acide nucléique grâce à la modification du point focal. Enfin, un peptide thérapeutique aux propriétés protectrices dans le lupus érythémateux disséminé, P140, a été couplé à un dendron à base d’adamantane à 3 branches et nous avons analysé les effets biologiques du trimère en comparaison avec le monomère. / Dendrons (wedge-shaped dendrimer sections) have been investigated as ideal nanoscale carrier molecules for the delivery of bioactive materials into the cells. Molecular engineering of these hyperbranched, monodisperse, well-defined structures can be easily performed using simple organic synthesis. Multivalency constituted by the multiple surface groups at the periphery of a dendron promotes higher binding affinity for ligand/receptor interactions. Adamantane molecule is a rigid structure consisting of four cyclohexane rings fused in chair conformation. The well-defined 3D conformation, the hydrophobicity and the lipophilicity provide to adamantane-based compounds favorable properties for their transport through biological membranes. In this context, the first part of this work was focused on the design and the synthesis of a novel type of polycationic dendrons based on adamantane, which are able to penetrate into cells without triggering cytotoxic effects. The next study of this Thesis concerned the investigation of our polycationic adamantane-based dendrons for gene delivery. We evaluated the capacity of the dendrons to complex a plasmid DNA. Hydrophobic compounds (biotin and cholesterol) were covalently bound to the focal point of the dendrons via “click” chemistry and the effects of the dendron generation, the peripheral cationic groups, and the hydrophobic modifications on the formation and stability of the complexes were studied. Finally, the dendrons constituted of an adamantane core, a focal point and three arms, were synthetized starting from a multifunctional adamantane derivative. We have coupled P140, a therapeutic peptide with protective properties in systemic lupus erythematosus, to an adamantane-based dendron and we have analyzed the biological effects of the resulting trimer compared to the monomer.

No description available.