NMR spectrum of monomers

The overall yield of the four-step synthesis of SOCM from glycerol was 72%. The monomer was characterized by IR, and NMR and by HPLC (Whatman Partisil 10 silica column with 9 1 hexane-ethyl acetate as eluant) analyses. The IR spectra of intermediates 6 and 7 as well as the SOCM monomer 3 are provided in Figure 4. The C NMR spectrum of monomer 3 is shown in Figure 5. 

The H NMR spectrum of monomer 11 is shown in Figure 5. The methyl of the methacrylate imit appears as a singlet at 1.73, and the protons of the other methyl group resonate at 1.90 ppm. The methylene protons at 2.20 and 2.54 are triplets, each integrating for two protons, while the two methylenes between the esters appear as a singlet integrating for four protons at 4.33 ppm. The cyclopentadienyl protons resonate as a singlet at 5.37 ppm, and the olefinic protons appear as two peaks at 5.65 and 6.06 ppm. The complexed aromatic protons appear as two sets of doublets at 6.50 and 6.81, and the uncomplexed aromatic protons are also split into two sets of doublets at 7.32 and 7.47 ppm. 

Figure 19 shows the HH COSY NMR spectrum of monomer 32a. The cyclopentadienyl protons resonated at 5.25 ppm, while the complexed aromatic protons were found at 63-6.5 ppm. The uncomplexed aromatic protons resonated further downfield between 7.2 and 7.5 ppm, while the olefinic protons of the norbornene unit were found in the range of 6.12-6.26 ppm. The aliphatic norbornene protons were found furthest upheld between 1.39 and 3.38ppm. 

C NMR spectrum of monomer 1 (b) showed peak at 163.11 ppm, which was due to the azomethine carbon (-CH=N-) and thus ctMifirms the formation of azomethine linkage. In addition, the carbons of the aromatic rings appeared at 112.3-131.2 and 148.7,149.8 and 151.9 forC-N and C-O, respectively. Elemental analysis (CHN) data also supported the formation of the expected monomers and confirmed the calculated data. 

The H-NMR spectrum of 2 in CDCI3 (Figure 1) exhibits broad unresolved resonances in the aromatic region similar to those found in the monomer. Broad signals with lack of resolution are consistent with magnetic non-equivalence of the methyl group protons resulting from a mixture of triad tacticities. 

Figure 15 Expansion (3.60-5.20 ppm) of ethylene glycol region of the H NMR spectrum of PET, when di-methyl terephthalate has been used as the monomer.

The NMR spectrum of the copolymer prepared from an equimolar mixture of the monomers is shown in Figure 10. In this spectrum, five well separated regions of NMR peaks were observed. The assignments of the peaks (Table III) were made by using the existing spectral information on homopolymers of 1-hexene and 5-methyl-1,4-hexadiene as well as the intensity variations among the copolymers with different monomer charge ratios. 

For NMR spectroscopic experiments, a thin film of pTrMPTrA was prepared by reacting a quantity of monomer and photoinitiator confined between glass plates with 1 mm separation. The polymerization conditions were the same as those for the photocalorimetry experiments. After 1 hour of UV exposure, the film was removed from the plates and ground to a fine powder using a mortar and pestle. A solid-state 13C NMR spectrum of the powder was obtained immediately, as described below. The remaining polymer powder was divided into two portions, one of which was stored under atmospheric conditions. The other portion was stored under N2. After one week, 13c spectra were again obtained for each of these polymer samples. Both samples were then heated to 280 °C in a vacuum oven and analyzed once more by 13C NMR spectroscopy. 

Figure 1. Top Original "tennis ball" monomer 1, its syn- the guests and 129Xe-NMR spectrum of a solution of 1 1 thesis, and analogs 2 and 3. Bottom left X-ray structure of with Xe added. Due to the aromatic centerpieces of the cap-...

Bottom right Upfield region of the 1H-NMR spectrum sule monomers, signals for the encapsulated guests are gen-... 

Figure 1 shows the proton noise-decoupled C-NMR spectrum of a polytetrahydrofurein (polytetramethylene ether glycol, PTMEG) dissolved in THF. In this spectrum the carbons numbered 1, 2 and 3 which cure a to the oxygen appear at lower field them the 6-carbons labeled as 4, 5 and 6. The carbon atoms in the polymer are clearly resolved from the corresponding carbons of the THF monomer. The fact that carbons 3 and 4 near the hydroxyl end-groups can be easily identified shows the excellent resolution of this technique. 

Exchange Reactions In Hydroxylic Media. Compounds 1 and 2 (Scheme 4) Interconyert readily at room temperature under acid catalysis. The equilibrium fayors the latter. Only 4.0% of 1 (R =Me) forms from 2 In excess MeOH. Unblocked aldehyde (Scheme 4) 1s observable (GC, NMR) under certain conditions as an unstable Intermediate In the aqueous hydrolysis of 1 to 2 (R=H). It Is not detectable In the IR or NMR spectrum of 2. Although k1net1ca lly accessible, the aldehyde Is thermodynamically disfavored. As a result, the degradative chain transfer and rapid a1r oxidation observed with unblocked aldehyde containing monomers and polymers (10) 1s avoided. 

When the NMR spectrum of a 30% (w./v.) solution of peroxide in toluene was recorded at 34°C., absorption was observed between 8 2.74 and 5.46. There were seven main resonances, all multiplets, which were interpreted in terms of aliphatic hydrogen shifted by oxygen. Resonance from ethylenic hydrogen amounted to only a fraction of a proton. However, the sample darkened while in the instrument and probably decomposed extensively. When the spectrum of a solution of peroxide prepared by oxidation to 10.4 mole % was recorded using a cold probe at —35°C. a different picture was obtained. There was complex absorption from both ethylenic and saturated hydrogen which was interpreted as arising from a mixture of 1,2 and 1,4 oxygen copolymers in an approximate jatio of 1 to 2. In this sample the residual chloroprene amounted to 0.15% of the monomer units in the peroxide and dimers of chloroprene to 0.6% of the peroxide. 

Soon after the isolation of 136, Tokitoh et described the synthesis of the first kinetically stabilized diarylstannylene stable in solution, that is, Tbt(Tip)Sn (169), by treatment of TbtLi with stannous chloride followed by addition of TipLi (Scheme 14.74). Under an inert atmosphere, stannylene 169 was found to be quite stable even at 60 °C in solution, and it showed a deep purple color (A,max =561 nm) in hexane. The Sn NMR spectrum of 169 showed only one signal at 2208 ppm, the chemical shift of which is characteristic of a divalent organotin compound as in the case of a monomeric dialkylstannylene (136). The bandwidth and the chemical shift of 169 were almost unchanged between —30 and 60 °C, indicating the absence of a monomer-dimer equilibrium. 

NMR spectroscopy is also a powerful technique for monitoring ring transformation processes in solution. For example, the N NMR spectrum of a solution of (NSC1)3 in carbon tetrachloride has been used to determine the thermodynamic parameters for the equilibrium between this six-membered ring and the monomer NSCl in solution [eqn (3.1)]. ... 

While most vinyl ketones readily undergo radical polymerization, and can only be stored in the monomeric state if an inhibitor is present, this enone failed to polymerize with either benzoyl peroxide or azobisisobutyronitrile under a variety of conditions. Examining the C-13 NMR spectrum of the monomer provides some insight into the lack of reactivity displayed by this unsaturated ketone. 

Oligomerization in these solutions is most certainly complicated. Figure 4 shows the Si-29 NMR spectrum of 90 wt % APS in heavy water vs. time at room temperature. The Si-29 isotope is only about 4.7% of the silicons. Consequently, sensitivity suffers and recording real-time Si-29 NMR spectra is difficult. The spectra of Fig. 4 are normalized and only the NO band is prominent. The NO band is seen to decay with increasing time as the APS monomers are used up in self-oligomerizations. Because of the poor signal-to-noise, the N1 band and the... 

Exactly the same result was obtained when the homopolymers were oxidized at — 25°C with a N,N,N, N -tetraethylethylenediamine-cuprous chloride catalyst, conditions which have been reported to cause coupling of DMP homopolymers solely by rearrangement (14). The NMR spectrum of this polymer is shown in Figure 3, together with the spectra of a mixture of homopolymers and of a random copolymer formed by simultaneous oxidation of the monomers. Apparently, dissociation and redistribution occur often enough to determine the structure of the product in this system, even under conditions that favor coupling of polymer molecules by the rearrangement mechanism. 

In order to assign the 29Si chemical shift relevant to the bonding between PDMS and TEOS relative to TMS, the liquid-state 29 Si NMR spectrum of the solution of the dimethyldiethoxysilane (DMDES)/TEOS system was recorded. DMDES is a monomer of PDMS and can form chains (equations 4 and 5), rings (especially cyclic D4 tetramers in this acid catalyzed system75) (equation 6) and copolymerized species with condensed TEOS (equation 7). 

The 5-substituted cyclooctenes (106-116, 118) generally give unbiased polymers, the substituent being too far away from the reaction site to influence the direction of addition of monomer. This is particularly clearly seen in the 13 C NMR spectrum of the polymer of 118, made using 19 as initiator, the olefinic region consisting of two well-defined symmetrical quartets (1 1 1 1) attributable to cis and trans olefinic carbons within HH, HT, TH, TT structures362. 

In the 13 C NMR spectrum of a statistical copolymer of monomers Mi and M2 four groups of olefinic peaks may be seen, corresponding to M1M1 and M2M2 dyads, and... 

NMR results are quantitative. Analysis of a 13C or H spectrum would reveal the different types of functionalities, as well as their contents in the sample. For example, Figure 9 shows the H NMR spectrum of the diene (ENB) in an EPDM polymer (ethylene-propylene diene monomer). 

---