Norbornadiene

About: Norbornadiene is a research topic. Over the lifetime, 2389 publications have been published within this topic receiving 38603 citations.

Norbornadiene as a Universal Substrate for Organic and Petrochemical Synthesis

Abstract: A wide range of rare polycyclic hydrocarbons can be obtained through catalytic processes involving norbornadiene (NBD). The problem of selectivity is crucial for such reactions. The feasibility of controlling selectivity and reaction rate has been shown for cyclic dimerization, co-dimerization, isomerization and allylation of NBD. Kinetic rules have been scrutinized. Consistent mechanisms have been proposed. Factors affecting directions of the reactions and allowing us to obtain individual stereoisomers quantitatively, have been established. A series of novel unsaturated compounds has been synthesized; they incorporate a set of double bonds with different reactivity and can find an extremely wide range of applications. Eurasian ChemTech Journal 3 (2001) 73-90  2001 al-Farabi Kazakh St.Nat. University Introduction The importance of NBD and its derivatives in various fields of human activity is growing. More and more new applications are being discovered for these compounds. Since they were first obtained less than 50 years ago, these substances have been successfully utilized in medicine, agriculture, rocketry, syntheses of polymers with unique properties, microelectronics, and as solar energy converters. The number of patents concerned with synthesis and application of NBD derivatives and norbornene-2 (NBN) had exceeded 100 hundreds by the year 2000. Due to their unique structure, compounds with NBD and NBNmoieties are achieving the leading positions in contemporary chemistry and chemical technology [1-3]. It should be strongly emphasized that NBD itself and some of its simplest derivatives are obtained from chemicals, produced on a large scale during oil processing [4]. They are cyclopenta-1,3-diene (CPD), acetylene, alkenes, and alkadienes with various structures. Production of CPD can easily be combined with synthesis of other petrochemical products, for example ethylene. Today, a large proportion of CPD cannot be duly utilized, so it is very important to search for new ways of its utilization. Even though NBD has extremely rich synthetic possibilities, its utilization as a universal substrate is rather limited, since NBD-derivatives can form all kinds of isomers: skeleton, regio, stereo, enantio ones. A resultant mixture of isomeric products is often difficult to separate and analyze, and the consumption of reagents may become excessive. All this restricts widespread use of NBD. Metal-complex catalysis is very interesting and attractive for solving various problems connected with selectivity [5]. By applying its tenets and methods to reactions involving NBD and its derivatives, by scrutinizing mechanisms of reactions, we can control structure and range of regioand stereo isomers, synthesize new compounds of this type, and can make their production sensible from technological and economical points of view. The present article bases on several research directions concerned with application of the above-mentioned methods in some of the most promising processes involving NBD.

Remote sensitized photoisomerization via through-bond triplet-triplet energy transfer mediated by a salt bridge in a supramolecular dyad.

Abstract: A s upramol ecul ar dyad, BP-(amidinium-carboxylate)-NBD is constructed, in which benzophenone (BP) and norbornadiene (NBD) are connected via an amidinium-carboxylate salt bridge. The photophysical and photochemical properties of the assembled BP-(amidinium-carboxylate)-NBD dyad are examined. The phosphorescence of the BP chromophore is efficiently quenched by the NBD group in BP-(amidinium-carboxylate)-NBD via the salt bridge. Time-resolved spectroscopy measurements indicate that the lifetime of the BP triplet state in BP-(amidinium-carboxylate)-NBD is shortened due to the quenching by the NBD group. Selective excitation of the BP chromophore results in isomerization of the NBD group to quadricyclane (QC). All of these observations suggest that the triplet - triplet energy transfer occurs efficiently in the BP-(amidinium-carboxylate)-NBD salt bridge system. The triplet-triplet energy transfer process proceeds with efficiencies of approximately 0.87, 0.98 and the rate constants 1.8 × 10 3 s -1 , and 1.3 × 10 7 s -1 at 77 K and room temperature, respectively. The mechanism for the triplet-triplet energy transfer is proposed to proceed via a "through-bond" electron exchange process, and the noncovalent bonds amidinium-carboxylate salt bridge can mediate the triplet-triplet energy transfer process effectively for photochemical conversion.

Synthesis and Photo Valence Isomerization of Polyamide Bearing Norbornadiene Unit

Abstract: Polyamides bearing norbornadiene (NBD) unit were prepared by the reaction of either bis(p-nitrophenyl) 2,3-NBD-dicarboxylate or a mixed anhydride bearing at the NBD moiety with various diamines. Films made of the polyamides indicated reversible UV-spectrum changes with UV irradiation, suggesting the occurrence of the photo-valence isomerization between the NBD and quadricyclane units.