Diethynylbenzene reaction

Surprisingly, the simplest graphdiyne model, PDM 1, had eluded synthesis. Even though substituted derivatives (e. g. 75,85) have been prepared by the standard cyclooligomerization reaction of o-diethynylbenzenes, isolation of the parent molecule failed via this method [8,51]. Utilization of an intramolecular... 

Another limitation of the traditional Cu-mediated cyclooligomerization reaction is generation of differentially substituted PDMs. In the above case, the substitution pattern in the starting o-diethynylbenzene must be maintained on each and every benzene moiety in the oligomeric mixture of PDMs that is produced. Thus, it is impossible to prepare less symmetric systems like 100 via this route. With the intramolecular synthetic approach, however, it should be possi-... 

The diethynylbenzene analogues, depending on their individual properties, can be evaporated or sublimed into the reaction zone. The lower limit of the deposition temperature for poly(naphthalene) (PNT-N) was explored, and it was observed that deposition began at a substrate temperature somewhere in range of 150-200°C. A summary of the poly(naphthalene) and poly(tetrafluoronaphtha-lene) deposition conditions described here is given in Table 18.6. 

Intramolecular cyclization of o-diethynylbenzene gives us an opportunity to compare results of the thermal and cation-radical variants of the reaction. There are three possible modes of cyclization shown in Scheme 7.25. 

Scheme 7.26 reflects the final result of the reaction. The initial step of this reaction consists of one-electron oxidation of the substrate. The resulting cation-radical of o-diethynylbenzene transforms into a fulvenyl intermediate, which further reacts with the neutral substrate to yield fulvenyl... 

Water-soluble PPEs have been made by the suitable choice of ionic and highly hydrophilic side chains. These PPEs will play a role in bio-type sensing applications (vide infra). A clever example is Schanze s synthesis of a sulfonato-substituted PPE [40, 41]. The NaOH-promoted reaction of [1, 2]oxathiolane-2,2-dioxide with 2,5-diiodohydroquinone gives a bis-sulfonate that can be coupled (Pd-catalyzed) to 1,4-diethynylbenzene to form a water-soluble PPE (Scheme 4) Table 6, entry 1). In a similar approach, Schanze et al. [42] made a... 

The pyrrole-functional polymer (160) is actually formed by reaction of p-diethynylbenzene (159) and a 1,3-dipolar mesoionic dioxazolone (161), which is formed in situ from bis(amino acid) (158) and acetic anhydride (Scheme 55). 

Pyrazole incorporation was effected by reaction of hydrazine with poly(diethynylbenzene) (190 Scheme 91) (72MI11108). The pyrazole-functional adduct (191) was a white, fibrous material soluble in DMF, DMSO, pyridine and formic acid. Films of the polymer were quite strong and were equally stable in air or nitrogen, with decomposition occurring at ca. 450 °C. 

Intramolecular cyclization of o-diethynylbenzene gives us an opportunity to compare the results of the thermal and cation radical variants of the reaction. There are three possible modes of cyclization (Scheme 6-21). While 1,6 cyclization takes place in the thermal process, cation radical initiation leads to 1,5 cylization (Ramkumar et al. 1996). Chemical oxidation of o-diethynylbenzene bearing two terminal phenyl groups by tris(/>bro-mophenyl)aminiumyl hexachloroatimonate as the catalytic oxidizing agent in the presence of oxygen yields 3-benzoyl-2-phenylindenone in 70% yield (Scheme 6-22). 

Initial work based on the Diels-Alder reaction provided access to linear polybenzenes via copolymerisation (Fig. 4.22) [40]. Diethynylbenzene acts as dieno-phile, and bis(cyclopentadienone) as diene. 

The transition metal-catalysed coupling reaction of aryl halides with alkynes (alkynylation of aryl halides) is frequently also considered as a Heck reaction [68, 108-111], Polymers containing arylacetylene and diarylacetylene units in the backbone have been obtained by the self-coupling of ethynylaryl halides [scheme (3)] and the cross-coupling of aromatic dihalides with acetylene [scheme (6)] or diethynylbenzenes [scheme (7)] [112-121]. The majority of... 

The classic synthesis of PPEs is the Pd/Cu-catalyzed coupling of diethynylbenzenes 45 with diiodo- or dibromobenzenes 46 [1]. This coupling reaction is widely applicable, quite... 

The polymerization reactions of bistetracyclone monomers XXIa-e with both m- and p-diethynylbenzene (XVII and XVIII) produced a series of polymers (XXII, Reaction 15) containing short blocks of phenylene units connected by methylene chains. High molecular weight polymers were obtained (Table II), and a range of physical properties was observed. 

As depicted in Scheme 4, the treatment of 1,4-diethynylbenzene with 2eq. of diphenylbromoborane (selective haloboration) and the subsequent reaction with leq. of tolylene-2,4-diisocyanate (phenylboration polymerization) gives the corresponding alternating copolymers. 

Similar azulene dimers arise on irradiation of 1,2-diethynylbenzenes (equation 65) , and an intramolecular napthalene-type adduct from a 1,8-diethynylnaphthalene (equation 66) . Interestingly, the latter reaction can also be brought about thermally. 

An azulene (36) having two intramolecularly crossing ethynyl groups was obtained together with its isomer (37) on irradiation of o-diethynylbenzene (35) and no further photochemical reaction was observed . On the other hand, o-bisphenyl-ethynylbenzcne (38) gave an azulenophenalene system, verdene (39), on irradiation . The mechanism of the formation of 39 was considered as a result of further cycloaddition of two triple bonds crossed in an intermediate azulene derivative (40). This photochemical reaction is reminiscent of the Biichi reaction in which diphenyl-acetylene yields an azulene system. 

The silyl-carborane hybrid diethynylbenzene-silylene polymer is prepared by a hydrosilylation reaction between diethynylbenzene-silylene polymer with the reactive vinyl side group and the 1,7-bis(dimethylsilyl)carborane group in toluene as solvent.The weight-average molecular weight of the polymer is determined to be 22,400 by using JASCO 802-SC gel permeation chromatography (GPC). The samples cured at 350 and 500° C are molded at 250°C for 6 min and pressed at 1795 kg/cm under vacuum for 30 s. 

Fig. 30. A scheme for thermosetting mechanism of silyl-carborane hybrid diethynylbenzene-silylene polymer by diene reaction between theC=C group and Ph-C=C group.

The first anionic polymetallayne of gold(I), P83, was prepared in moderate yield (36%) from the reaction of PPN[Au(acac)2] (PPN = bis(triphenylphosphine)iminium) with 1,3-diethynylbenzene in a 1 1 stoichiometric ratio.104 It was characterized by IR and H NMR spectroscopies. More interestingly, efforts were made to make two novel anionic heteronu-clear Pt(II)-Au(I) cr-acetylide polymers exhibiting both the linear (P84) and branched (P85) forms, but these polymers possessed very poor solubility in all common organic solvents.105... 

The synthesis of conjugated polymers by the addition polymerization of 1,4-benzenedithiol and 1,4-benzenediselenol to 1,4-diethynylbenzene has been accomplished by means of free-radical reaction. For example, the polymerization of 1,2-benzenediselenol (equation 17) proceeds at such a fast rate as to give 60-70% yield in 6 min. The polymer was isolated and characterized in the cisitrans content of double bonds, finding a ratio of 90/10. The isomerization of the cis double bond has been obtained by UV irradiation for longer reaction times (18 h). 

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