1.3.5.7- tetrakis adamantane

Molecules with tetrahedral symmetry can be realized with adamantane cores or tetrasubstituted sp3 centers (Fig. 3.15). Braun et al. [92] synthesized some adamantane glasses with glass transition temperatures of 116°C for 1,3,5,7-tetrakis (biphenyl-4-carbonyloxy)adamantane (45a) and 118°C for 1,3,5,7-tetrakis (4-iodobenzoyloxy)adamantane (45b), respectively. It is interesting to note that if the direction of the ester linkage is reversed (esters of adamantanetetracar-boxylic acid), Tg is lowered by 30 K. 

Dioxoadamantane-l,3,5,7-tetracarboxylic acid reacts with sulfur tetrafluoride in a conventional way to give high yields of 2,2,6,6-tetrafluoro-1,3,5,7-tetrakis(trifluoromethyl)adamantane... 

Desulfuration of thiols.2 Aromatic, benzylic, and aliphatic thiols are converted into hydrocarbons when heated in acetic acid with molybdenum carbonyl. The bridgehead adamantane-l-thiol is an exception and gives instead a thioester, RSCOCHj. Yields are 50-90%. The actual reagent is probably tetrakis(acetato)-dimolybdenum.3 Molybdenum carbonyl deposited on silica can also be used. 

Similar chemistry starting out from tetrakis(chloromethyl)methane (288) was published by Eller-mann and Brehm. Treatment with NaAsPhj in liquid ammonia gives the tertiary arsine (289). Reaction of (289) with gaseous HI forms the trisdiiodoarsane (290). The hetero-adamantanes (291a, b) are obtained on solvolysis of (290) with H2O/NH3 and H2S (Scheme 48) <85CB4794). 

Figure 2.7 shows several examples of [bis(acyloxy)iodo]arenes whose X-ray crystal structures have been reported in literature. These structures include the chiral diacetate 31 [191], p.-oxodiiodanyl diacetate 57 [117], A-tosyM-(diacetoxyiodo)pyrazole (58) [133], l,3,5,7-tetrakis[4-(diacetoxyiodo)phenyl]adamantane (59) [154], tetrakis[4-(diacetoxyiodo)phenyl]methane (60) [155], 3-[bis(trifluoroacetoxy)iodo]benzoic acid (61) [186], l-(diacetoxyiodo)-2-nitrobenzene (62) [94] and the chiral (diacetoxyiodo)arene 63 [165] derived from methyl lactate. 

This procedure is performed at room temperature in a DMF-tetrahydrofuran (THF) solvent mixture. The surface area of PPN-4 approximates the molecular modelling simulation value. This clearly shows the superiority of this process. The 3D monomer coupling with tetra-kis(hromophenyl)adamantane by a Yamamoto reaction has been done independently by Holst et and Lu et al. (PPN-3). The surface areas were 3180 and 2840 m g, respectively. Using the same process to homocouple tetrakis(ethynylphenyl)adamantane (PPN-2) gives a network exhibiting a BET surface area of 1764 m ... 

In the case of the hydroxylation of inactivated alkanes, the yields and distributions of products are sensitive to the peripheral substitution pattern of the porphyrin. Table 4 lists the results from the oxidation of adamantane with iodosylbenzene and three iron porphyrins Fe (TPP)Cl, Fe (TTP)Cl (TTP tetrakis(o-tolyl)porphyrin), and Fe (TMP)Cl [44]. Apparently, there is a high degree of selectivity for tertiary centers over secondary centers. In addition, with increasing substitution of the porphyrin peripheral groups, the relative reactivity of tertiary and secondary hydrogens decreased from 48 1 to 11 1. Details of the steric effect of the porphyrin peripheral groups to the selectivity will be discussed later. 

N-substituted benzimidazole-containing bridged alicyclic compound are manufactured and used [92] to produce thin films having a pore structure on a molecular level, high thermal stability, low relative dielectric const., and low moisture absorptivity, useful in manufacture of semiconductors. Thus, reaction of 1,3,5,7-tetrakis(4-carbonylphenyl)adamantane with 3,3 -diaminobenzidine,... 

Compound 3 is an example of a star polymer with benzoxazole arms. The three dimensional rigid-rod polymer was obtained from the polycondensation of 4-[5-amino-6-hydroxybenzoxazol-2-yl]benzoic acid (ABA) with l,3,5,7-tetrakis(4-carboxylatophenyl)adamantane (TCBA) in polyphosphoric acid (PPA). Polymer structures were confirmed by FTIR and elemental analysis, although the extent of attachment of PBO arms to the adamantane core was not confirmed. In addition, stir opalescence was observed indicating lyotropic-like behavior. However, the more compact star structure resulted in intrinsic viscosities that were significantly less than linear PBO s obtained under identical conditions. The onset for weight loss under TGA in air occurred at 500 C for both linear and star polymers and no transitions were observed by DSC. 

Figure 6. 13,5,7-tetrakis(4-ethynylphenyl)adamantane and 13,5,7-tetrakis(4-phenylethynylphenyl)adamantane. 

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