L- propylene oxide

The polymerization of (-l-)-propylene oxide also belongs to this class since the opening of the three-member ring occurs mainly at the primary carbon... 

Saba,R.G., Sauer,J. A., Woodward,A.E. Dynamic shear behavior of poly (y-benzyl L-glutamate), poly(D, L-propylene oxide), and polyfethyl vinyl ether). J. Polymer Sd. A1, 1483 (1963). 

Figure 2. A comparison of product TPD spectra obtained after exposure of 1.6 L propanal, 2.3 L 1-propanol, or 2.1 L propylene oxide to the clean Rh(l 11) surface at ca. 91 K.

Polymerization of l-Propylene Oxide with Potassium Hydroxide. 408... 

When D,L-propylene oxide was used in a similar preparation, an optically inactive product formed. 

Special relationships apply, however, when configurationally different but constitionally identical monomers are copolymerized. An example of this is the polymerization of D- and L-propylene oxide mixtures. Here, it is important to distinguish sharply between stereospecific and stereoselective polymerizations. The meaning of these two terms is not the same as the corresponding meaning of stereospecific and stereoselective reactions in low-molar-mass organic chemistry. 

Stereoregular polymers of infinite molecular weight, dissymmetric main-chain atoms, and dissymmetric substituents show no optical activity resulting from the configuration, because of intramolecular compensation. Thus, isotactic poly(propylene) is not optically active. Stereoregular polymers with asymmetric main-chain atoms, such as - NH—CH(CH3)— poly(L-alanine), and -[-O—CH(CH3)—poly(L-propylene oxide), are optically active because of the configuration itself. 

Part of the optical inactivity in the amorphous fraction can be attributed to racemization during addition since unreacted l-propylene oxide showed no loss of activity. The remainder of the inactivity must result from head-to-head and tail-to-tail additions (Vandenberg, 1964). 

Propylene oxide has an asymmetric carbon atom. The normal commercial epoxide is a racemic mixture of the d- and 1-isomers. Osgan and Price did extensive work with both the 1-propylene oxide and the d,l-propylene oxide in both potassium hydroxide and ferric chloride/propylene oxide-initiated polymerizations. Their results are summarized in Table 5 (48). C. C. Price and coworkers first demonstrated that polymerization of pure 1-propylene oxide with an anhydrous potassium hydroxide (solid KOH) initiator led to a crystalline, rather than the usual amorphous, liquid, polymer. After extensive study by a number of researchers (69), this polymerization was shown to proceed by a stepwise anionic mechanism. The uses found for polymers of propylene oxide largely have been those requiring the amorphous polymer in elastomeric applications. Stereospecificity, however, has proved to be a key tool in understanding the polymerization mechanisms. 

Homopolymers of PO and other epoxides are named a number of ways after the monomer, eg, poly(propylene oxide) (PPO) or polymethjioxirane from a stmctural point of view, polyoxypropylene or poly(propylene glycol) or from the Chemicaly hstracts (CA) name, poly[oxy(methyl-l,2-ethanediyl)], a-hydro- CO-hydroxy-. Common names are used extensively in the Hterature and in this article. 

Hydrogen Sulfide andMercaptans. Hydrogen sulfide and propylene oxide react to produce l-mercapto-2-propanol and bis(2-hydroxypropyl) sulfide (69,70). Reaction of the epoxide with mercaptans yields 1-aLkylthio- or l-arylthio-2-propanol when basic catalysis is used (71). Acid catalysts produce a mixture of primary and secondary hydroxy products, but ia low yield (72). Suitable catalysts iaclude sodium hydroxide, sodium salts of the mercaptan, tetraaLkylammonium hydroxide, acidic 2eohtes, and sodium salts of an alkoxylated alcohol or mercaptan (26,69,70,73,74). 

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 glycol ethers obtained from /-butyl alcohol and propylene oxide, eg, l-/-butoxy-2-propanol, have lower toxicities than the widely employed 2-butoxyethanol and are used in industrial coatings and to solubiHze organic components in aqueous formulations (28). 

Fig. 2. Diagram of a typical chlorohydrin reactor for manufacture of propylene oxide. M.O.L. = milk of lime. To convert kPa to mm Hg, multiply by 7.5.

Epoxypropane, see Propylene oxide 2.3- Epoxy-l-propanol, see Glycidol ... 

Chemical Designations - Synonyms l,Chloro-2,3-epoxypropane Chloromethyloxirane gamma-Chloropropylene oxide 3-Chloro-1,2-propylene oxide Chemical Formula O-CHj CH CHjCl. Observable Characteristics - Physical State (as shipped) Liquid Color Colorless Odor Pungent, garlic sweet, pungent like chloroform. 

Treatment of (11 aS)-3-isopropyl-11 a-methyl-4-phenyl-1,6,11,11 a-tetrahy-dro[l,4]oxazino[4,3-6]isoquinolin-l-one (243) with 6N HCl in a pressure tube, then the reaction of the work-up residue with propylene oxide gave (3S)-3-methyl-l,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (244) (99S704). 

Detonabllity of Propylene Oxide/Air and N-Propyl Nitrate/Air Mixtures , Rept No AFATL-TR-73-3 (1973) 6) E.L. Husker, Tethered... 

P. Beatrice, C. Pliangos, W.L. Worrell, and C.G. Vayenas, The electrochemical promotion of ethylene and propylene oxidation on Pt deposited on Yttria-Titania-Zirconia, Solid State Ionics 136-137, 833-837 (2000). 

---