F 3-Methyl-l,2-butadiene

Fluoroethylene ozonide, 0752 /rMaleic anhydride ozonide, 1406 f 2-Methyl-1,3-butadiene, Ozone, 1893 3-Methyl-l,2,4-trioxolane, 1235 trans-2-Pentene ozonide, 1982... 

Methyl-2,5-dihydrothiophene 1-oxide in tetrahydrofuran added slowly to a well-stirred Grignard reagent prepared from bromobenzene and Mg-turnings in tetrahydrofuran, stirring continued 1 hr. at 0°, warmed to 25°, and stirred 20 hrs. at room temp. l-phenylthio-2-methyl-l,3-butadiene. Y 70%. F. e. s. D. W. Kreh and R. C. Krug, J. Org. Chem. 52, 4057 (1967). 

Estimate the ideal-gas heat capacity C° of 2-methyl-l,3-butadiene and -methyl-2-pyrrolidone at 527°C (800 K, or 980°F) using the group-contribution method of Rrhani and Doraiswamy. The Rihani-Doraiswamy method is based on the equation... 

Give abbreviated stmctnres of each of the following compounds (a) ( )-l,4-poly-2-methyl-l,3-butadiene [(i )-l,4-poly-isoprene] (b) l,2-poly-2-methyl-l,3-butadiene (1,2-polyiso-prene) (c) 3,4-poly-2-methyl-l,3-butadiene (3,4-polyisoprene) (d) copolymer of 1,3-butadiene and ethenylbenzene (styrene, QH5CH=CH2, SBR, used in automobile tires) (e) copolymer of 1,3-butadiene and propenenitrile (acrylonitrile, CH2=CHCN, latex) (f) copolymer of 2-methyl-1,3-butadiene (isoprene) and 2-methylpropene (butyl rubber, for inner tubes). 

Optically active Diels-Alder adducts were also prepared by using a one-pot preparative method and enantioselective formation of inclusion complex with optically active hosts in a water suspension medium. For example, A-ethylmaleimide reacts with 2-methyl-1,3-butadiene in water to give the racemic adduct 1. Racemic 1 and the optically active host 2 form enantioselectively a 1 1 inclusion complex of 2 with (-f)-l in a water suspension. The inclusion complex can be filtered and heated to release (-l-)-l with 94% ee (Eq. 12.23). 

FIGURE 3.5 Examples of isoprenoid lipids illustrating the structural diversity of the group, (a) Three isoprene units (2-methyl-1,3-butadiene) in various conformations (b) a-pinene (2,6,6-trimethylbicyclo[3.1.1]hept-2-ene) (c) P-farnescene (3,7,ll-trimethyl-l,3,10-dodec-atriene) (d) phytol (3,7,ll,15-tetramethyl-2-hexadecenol) (e) scalarin (12a-acetoxy-25a-hydroxyscalar-16-en-25,24-olide) (f) squalene (2,6,10,15,19,23-hexamethyl-2,6,10,14,18,22-tetracosahexaene) and (g) lanosterol (4,4,14a-trimethyl-5a-cholest-8,24-diene-3P-ol). 

Isoprene l-s3-ipren [prob. fr. is- - - propyl -f -ene] (1860) (3-methyl-1,3-butadiene, 2-methyl-1,3-butadiene) n. CH2=C-(CH3) CH=CH2- a colorless, volatile liquid derived from propylene or from coal gases or tars, chemically similar to the mer unit of natural rubber. Its polymer of the cis-1, 4-type of polyisoprene is chemistry s nearest approach to synthesizing the natural product and it has sometimes been called synthetic natural rubber . It has a molecular weight of 68.06, a mp of—120°C, and a bp of 34°C. Ash M, Ash I (1982-1983) Encyclopedia of plastics polymers, and resins, vols 1-3. Chemical Publishing Co., New York. 

The three- and four-layered schemes will be examined for two Diels-Alder reactions. The addition of acrolein to 2-t-butyl-1,3-butadiene will be examined with the threelayered ONIOM approach where the model will be taken as ethylene + butadiene, the intermediate model as acrolein 4-isoprene, and the real system as acrolein-f 2-l-butyl-1,3-butadiene. The three ab initio levels of theory will be G2MS CCSD(T)/6-31 G(d) -f MP2/6-311+G(2df,2p) -MP2/6-31G(d), MP4(SDQ), and MP2. This three-layered approach will be extended to a four-layered method by replacing the nine r-butyl hydrogens with methyl groups. This becomes the real system, acrolein -f 2-(trimethyl)-r-butyl-1,3-butadiene, with acrolein-f 2- -butyl-1,3-butadiene as the intermediate large model (int.L.model), acrolein -f isoprene as the intermediate small model (int.S.model), and ethylene-f butadiene as the small model (S.model). The four levels of theory are G2MS, MP4(SDQ), MP2, and HF. The geometry of the transition state and reactants have been optimized... 

Section II, 1. Theoretical aspects of asymmetric polymerization have been discussed by Fueno and Furdkawa [T. Fueno, J. Furukawa J. Polymer Sci., Part A, 2, 3681 (1964)]. 1-phenyl-l,3-butadiene has been polymerized using (R)-2-methyl-butyl-lithium or butyl-lithium complexed with menthyl-ethyl-ether, yielding optically active polymers with [a] f, referred to one monomeric unit, between +0.71 and —1.79. Optical rotation dispersion between 589 m u and 365 mft is normal and the Drude equation constant is comprised between 255 raft and 280 raft [A. D. Aliev, B. A. Krenisel, T. N. Fedoiova Vysokomol. Soed. 7, 1442 (1965)]. 

The phase-stabilized AN is prepd by mixing 90 parts AN, 10 ps K nitrate some water, heating the mixt to 140°F, drying and grinding to 40 micron size particles. The proplnt is compressed into grains. Example of compn AN 82.95, K nitrate 9.22, petroleum pitch 4.11 90/10 copolymer of l,3-butadiene/2-methyl-5 -vinyl pyridine 1.76 Amm dichromate 1.96%] EE)R.MacDonald A.M.Bedard, "Methods of Chemical Analysis of Cardeplex Propellant No 4760/A5 and Its Ingredients", CARDE TR426/63 (1963) (Cardeplex No 4760/A5 is a composite ammonium perchlorate-polyurethane proplnt. Analysis of fully cured product includes detns of Amm perchlorate, Al, ferric acetylacetonate, phenyl-/3 -naphthylamine, lithium fluoride total iron) FF)Anon,... 

A solution of 640 mg (5 mmol) of methyl 2,3-dideoxy-Di,-pent-2-enopyranosc-4-ulosc (21) and 820 mg (10 mmol) of 2.3-dimethyl-l.3-butadiene (22h) in 9 mL of F,r2G is subjected to 8.2x 10s Torr pressure for 20 h at 20 + 2 C. After expansion the reaction mixture is filtered. EtzO is evaporated and the product is isolated by column chromatography (hcxane/Et20 9 1) to give 23b yield 950 mg (91 %). 

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