Alkylene cyclic

Cyclic compounds capable of undergoing ring opening (alkylene oxides, lactones, lactams, anhydrides, etc.). 

Dialkyl peroxides have the stmctural formula R—OO—R/ where R and R are the same or different primary, secondary, or tertiary alkyl, cycloalkyl, and aralkyl hydrocarbon or hetero-substituted hydrocarbon radicals. Organomineral peroxides have the formulas R Q(OOR) and R QOOQR, where at least one of the peroxygens is bonded directly to the organo-substituted metal or metalloid, Q. Dialkyl peroxides include cyclic and bicycflc peroxides where the R and R groups are linked, eg, endoperoxides and derivatives of 1,2-dioxane. Also included are polymeric peroxides, which usually are called poly(alkylene peroxides) or alkylene—oxygen copolymers, and poly(organomineral peroxides) (44), where Q = As or Sb. 

Polyether Polyols. Polyether polyols are addition products derived from cyclic ethers (Table 4). The alkylene oxide polymerisation is usually initiated by alkah hydroxides, especially potassium hydroxide. In the base-catalysed polymerisation of propylene oxide, some rearrangement occurs to give aHyl alcohol. Further reaction of aHyl alcohol with propylene oxide produces a monofunctional alcohol. Therefore, polyether polyols derived from propylene oxide are not truly diftmctional. By using sine hexacyano cobaltate as catalyst, a more diftmctional polyol is obtained (20). Olin has introduced the diftmctional polyether polyols under the trade name POLY-L. Trichlorobutylene oxide-derived polyether polyols are useful as reactive fire retardants. Poly(tetramethylene glycol) (PTMG) is produced in the acid-catalysed homopolymerisation of tetrahydrofuran. Copolymers derived from tetrahydrofuran and ethylene oxide are also produced. 

The only practical method for preparing alkylene thioureas is by the action of the diamines upon carbon disulfide in aqueous alcohol. The final heating is essential to convert the thio-carbamic acid into the cyclic compound, the addition of hydrochloric acid being beneficial. ... 

Brunelle, D. J., Bradt, J. E., Serth-Guzzo, J., Takekoshi, T., Evans, T. L. and Pearce, E. J., Semicrystalline polymers via ring-opening polymerization preparation and polymerization of alkylene phthalate cyclic oligomers, Macromolecules, 31, 4782 (1998). 

Cyclic sulfates can be obtained from diols or polyols in the reaction of the latter with SOCI2 followed by mthenium catalyzed oxidation. These sulfates readily react with LiPPh2 yielding mono- and di-tertiary diphenylphosphines having alkylene sulfate substituents (54-57). This is a highly versatile procedure, since the starting diols are readily available and the products are well soluble and fairly stable in neutral or slightly alkaline aqueous solutions [57,105]. 

Polyethers are prepared by the ring opening polymerization of three, four, five, seven, and higher member cyclic ethers. Polyalkylene oxides from ethylene or propylene oxide and from epichlorohydrin are the most common commercial materials. They seem to be the most reactive alkylene oxides and can be polymerized by cationic, anionic, and coordinated nucleophilic mechanisms. For example, ethylene oxide is polymerized by an alkaline catalyst to generate a living polymer in Figure 1.1. Upon addition of a second alkylene oxide monomer, it is possible to produce a block copolymer (Fig. 1.2). 

The reaction of alkylene oxides or epoxides with sulfur dioxide to give cyclic sulfites is effected by carrying out the reaction at about 150°C for 4 hr at 2000 atm of S02 [28]. Pyridine is used in small amounts as a polymerization inhibitor. In addition, it has been reported that free radical-producing catalysts give improved yields and allow the reaction to be carried out at lower temperatures [28] (Eq. 19). 

Among the variations in chemical structure of these triblock copolymers developed in our laboratories were the use of poly(a-methyl styrene)(43, 44) as end blocks, and poly(alkylene sulfides) (42, 45 ) 311 d polydimethylsiloxanes (43, 46) as center blocks. The reactions of cyclic sulfides with organolithium is illustrated in Figure 10. Both the propylene sulfide and the methyl thietane can be used for the center block with styrene or a-methylstyrene end blocks, but the chemistry shown in Figure 10... 

For a crystalline polymer, the melting temperature (Tm) may be observed for both the cyclic and the backbone in some cases. Poly(alkylene sebacate crown ether rotaxane)s 60 have two Tm values, those of the cyclic and the backbone [19, 111]. The crystallization of the crown ether on the backbone was attributed to aggregation enabled by the mobility of the crown ether along the backbone in solution or melt states. The crystallization process is driven by the tendency for these immiscible components to form their own separate phases to minimize interfacial energy. According to an X-ray diffraction study of polystyrene rotaxane)s 26... 

T0 prepare models of TA, the corresponding cyclic alkylene phosphoric acids cannot be directly polymerized because the presence of acidic protons of the phosphate group makes the ionic polymerization impossible. Thus, cyclic phosphorus compounds with blocked third functions have to be used. These are phosphates., phosphoramidates and phosphites. After polymerization the obtained polymer is converted by deblocking into the polyalkylene phosphate, e.g. polysalt or polyacid form. 

Although the cyclic selenohydrocarbons having five- or six-membered rings are isolated in good yield by the interaction of alkylene dibromides and sodium selenide, trimethylene dibromide and sodium selenide furnish only a small yield of c cZoselenopropane,... 

The first reports describing the formation of cyclic carbonates (CCs) appeared during the early 1930s [99, 100], whilst the first patents (essentially related to the synthesis of ethene and propene carbonates) appeared more than 50 years ago [101, 102]. The Huntsman Corporation is one the world s largest producers of alkylene carbonates, with a capacity of 33 kt per year, covering approximately 50% of CC production worldwide. Today, CCs are widely used in the manufacture of... 

The cyclic alkylene carbonates have also been applied as the cure-accelerators of phenol-formaldehyde (PF) [262-266] and sodium silicate [267] resin systems, which are widely used in foundry sand and wood binder applications. 

The transesterification of 1,2-diols by reaction with carbonates, both cyclic and linear, produces five-membered alkylene carbonates almost exclusively. A well-known example of this is the reaction of DMC with propene glycol to yield PC [295],... 

PMO precursors can be divided roughly into three classes bis-silylated compounds, which contain (1) short-chained alkylene or alkenylene groups as the organic bridge, (2) those with aromatic bridges, and (3) branched or cyclic multi-silylated compounds. An overview of the constitution formulae of PMO precursors is provided in Figure 3.11. 

The coordination polymerisation of cyclic esters concerns mostly lactones, especially those containing a four-membered ring in the molecule. There is, however, an interest in the coordination polymerisation of such oxacyclic ester monomers as lactide and alkylene carbonate and, to a lesser extent, in the... 

Copolymerisation of propylene oxide as well as other oxiranes with carbon dioxide in the presence of zinc-based coordination catalysts is generally accompanied with the formation of a cyclic five-membered carbonate, propylene carbonate or another alkylene carbonate [147,206,207,210,212,230]. The alky-lene carbonate, however, is not the precursor for poly(alkylene carbonate), since it hardly undergoes a polymerisation under the given conditions [142-146],... 

During the last 40 years, an enormous effort was put into searching for a solid catalyst [4, 5]. The main obstacle still to be overcome is the formation of acid-soluble oils (ASO, also known as conjunct polymers or red oil) which accompanies the alkylation process. This material contains highly unsaturated cyclic hydrocarbons, which rapidly passivate the catalyst. When liquid catalysts are used, they can be easily withdrawn from the process and replaced, without interrupting the alkylation operation. UOP has developed the Alkylene technology, which uses the proprietary HAL 100 catalyst in a process that is claimed to be commercially competitive [6]. 

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