Dimethyltrimethylene

2-dimethyltrimethylene (4) there are two different modes of conrotatory motion of the radical centers, leading to stereoisomeric cyclization products rotation by positive (a 0) and negative (a 0) values of the rotational angle yields cis- and rans-dimethylcyclopropane, respectively. 

0 kcal/mol lower in energy than By decreasing the bond angle y, geometries are accessible both from and at which Sq and T are degenerate 

From these results, it can be concluded that, as in the unsubstituted trimethylene, the reactive structure of optimal ISC is characterized by a face-to-face orientation of the radical centers and a CCC angle y slightly smaller than for the triplet minima. As the singlet PES drops steeply for small values of y, the triplet state yields preferably cyclic products. The conditions for optimal ISC are similar for both minima and therefore, the stereochemical differentiation 

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Figure 6.16 The ring-closure reaction of 1,2-dimethyltrimethylene. Contour diagrams of the surface and the SOC surface (a) of trimethylene and (b) of its 1,2-dimethyl derivative. Triplet-singlet intersection SgT = 0 is indicated by heavy lines.

Figure 7. Triplet PE (top) and SOC surfaces (bottom) for the ring-closure reaction of trimethylene (left) and 1,2-dimethyltrimethylene (right), as a function of the CCC valence angle y and the conrotatory motion (a = P) of the radical centers. SOC values vary between 0 cm in the middle of the diagram and 7.5 cm at the upper right and left corners. T -Sq intersection = 0 is indicated by heavy lines.

Preparation of bis-(2,2-dimethyltrimethylene)yl [(2,5-dimethyl-l,4-phenylene)dimethylene] diphosphonate —... 

A solution of the sodium salt of the cyclic 2,2-dimethyltrimethylene phosphite was prepared by the addition of a 57% mineral oil dispersion of sodium hydride (8.42 g, 0.2 mol) to a solution of the cyclic 2,2-dimethyltrimethylene phosphite (30 g, 0.2 mol) in dry dimethylforma-mide (150 ml) while the temperature was maintained below 30°C. To the resultant solution was added a solution of l,4-bis(chloromethyl)-2,5-dimethylbenzene (20.3 g, 0.1 mol) in dry dimethylformamide (150 ml). After the addition was complete and the exotherm subsided, the reaction mixture was heated at 60 to 65°C for 15 h. After the reaction mixture was cooled to room temperature, the solid that formed was... 

The coordination polymerisation of cyclic carbonates with a six-membered ring in the molecule, such as trimethylene carbonate (l,3-dioxan-2-one) and 2,2-dimethyltrimethylene carbonate (5,5-dimethyl-l,3-dioxan-2-one) [148-150], carried out in the presence of metal carboxylates e.g. zinc stearate, tin-based catalysts such as the di(w-butyl)stannic diiodide-triphenylphosphine system [151] or porphinatoaluminium compounds such as (tpp)AlOR [149] is not accompanied with decarboxylation and yields the respective polycarbonates (Table 9.2). The ring cleavage during the polymerisation of trimethylene carbonate and 2,2-dimethyltrimethylene carbonate in the presence of the above catalysts has been found [148,149,151] to occur at the C(0)-0 bond, resulting... 

The dual function of the precatalysts 4 opened the way to well-controlled block polymerization of ethylene and MMA (eq. (5)) [89, 90]. Homopolymerization of ethylene (Mn = 10000) and subsequent copolymerization with MAA (Mn 20000) yielded the desired linear AB block copolymers. Mono and bis(alkyl/silyl)-substituted flyover metallocene hydride complexes of type 8 gave the first well-controlled block copoymerization of higher a-olefins with polar monomers such as MMA or CL [91]. In contast to the rapid formation of polyethylene [92], the polymerization of 1-pentene and 1-hexene proceeded rather slowly. For example, AB block copolymers featuring poly( 1-pentene) blocks (M 14000, PDI = 1.41) and polar PMMA blocks (M 34000, PDI = 1.77) were obtained. Due to the bis-initiating action of samarocene(II) complexes (Scheme 4), type 13-15 precatalysts are capable of producing ABA block copolymers of type poly(MMA-co-ethylene-co-MMA), poly(CL-co-ethylene-co-CL), and poly(DTC-co-ethylene-co-DTC DTC = 2,2-dimethyltrimethylene carbonate) [90]. 

DIMETHYLTRIMETHYLENE GLYCOL (126-30-7) Combustible solid (flash point 265°F/129°C). Dust or powder forms explosive mixture with air. Incompatible with strong acids, caustics, aliphatic amines, isocyanates, oxidizers. 

Dimethyltrimethylene acrylate 2,2-Diinethyltriinethylene ester acrylic acid. See Neopentyl glycol diacrylate... 

CAS 2227,- 2-1 , EINECS/ELINCS 218-741-5 Synonyms Acrylic acid 3-acryloyloxy-2,2-dimethylpropyl ester Dimethylolpropane diactylate 2,2-Dimethylpropane-1,3-diacr te 2,2-Dimethyl-1,3-propanedk)l diactylate 2,2-Dimethyl-1,3-propanediol diester acrylic acid 2,2-Dimethyltrimethylene acrylate 2,2-Dimethyltri-methylene ester acrylic acid NPGDA 2-Propenoic acid-2,2-dimethyl-1,3-propanediyl ester ClassiTication Nonaromatic ester Empirical C H,60,... 

CAS 6846-50-0 EINECS/ELINCS 229-934-9 Synonyms Isobutyric acid, 1-isopropyl-2,2-dimethyltrimethylene ester ... 

Dimethyltrimethylene acrylate 2,2-Dimethyltrimethylene ester acrylic acid NPGDA 2-Propenoic acid-2,2-dimethyl-1,3-propanediyl ester... 

Trimethyl-1,3-pentanediol, 2,2,4-diisobutyrate CAS 6846-50-0 EINECS/ELINCS 229-934-9 Synonyms Isobutyric acid, 1-isopropyl-2,2-dimethyltrimethylene ester 2,2,4-Trimethyl-1,3-pentanediol bis (2-methylpropanoate) 2,2,4-Trimethylpentanediol-1,3-diisobutyrate 2,2,4-Trimethyl-1,3-pentanediol diisobutyrate Empirical C16H30O4 Formula ... 

Reaction of 3-bromo-2,2-dimethyl-l-propanol (53) with KOH in aqueous solution produced a 20% yield of 2,2-dimethyltrimethylene oxide (54) along with isobutylene and formaldehyde. Propose a mechanism to account for the formation of these products. 

Sebacic anhydride 2,2-Dimethyltrimethylene carbonate Tin-Depression Semicrystalline Wang et al. (2002a)... 

Dobrzynski, P., Kasperczyk, J., 2006a. Synthesis of biodegradable copolymers with low-toxicity zirconium compounds. IV. Copolymerization of glycolide with trimethylene carbonate and 2,2-dimethyltrimethylene carbonate microstructure analysis of copolymer chains by high-resolution nuclear magnetic resonance spectroscopy. Journal of Polymer Science Part A Polymer Chemistry 44, 98—114. 

Kricheldorf, H.R., Dunsing, R., Albet, A.S.i, 1987. Polylactones 12. cationic polymerization of 2,2-dimethyltrimethylene carbonate. Makromolekulare Chemie 188, 2453-2466. 

Kuhling, S., Keul, H., Hocker, H., 1990. Polymers from 2-allyloxymethyl-2-ethyltrimethylene carbonate and copolymers with 2,2-dimethyltrimethylene carbonate obtained by anionic ring-opening polyrmerization. Makromolekulare Chemie 191, 1611—1622. 

Yu, X., Zhuo, R., Feng, J., Liao, J., 2004. Enzymatic ring-opening polymerization of 2,2-dimethyltrimethylene carbonate catalyzed by PPL immobibzed on silica nanoparticles. European Polymer Journal 40, 2445—2450. 

Zhu, W., Ling, J., Xu, H., Shen, Z., 2005. Copolymerization of trimethylene carbonate and 2,2-dimethyltrimethylene carbonate by rare earth calixarene complexes. Polymer 46, 8379-8385. 

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