Propene allyl compounds

Bromo-l-propene (Allyl bromide) [106-95-6] H2C=CHCH2Br HCS 1980, 124 See other allyl compounds, haloalkenes C3H5Br... 

The versatile Ti(II) chemistry available using preformed (alkene)Ti(OiPr)2 species was opened up by the discovery of the Kulinkovich cyclopropanation reaction [55]. Since 1995, Sato and collaborators have developed a wide range of elegant and synthetically useful reactions based on the Ti(OiPr)4/iPrMgCl reagent [56]. In particular, it was reported that the Ti(II) complex (q2-propene)Ti(OiPr)2, preformed from Ti(OiPr)4 and 2 equivalents of iPrMgCl, reacts with allylic compounds, such as halide, acetate, carbonate, phosphate, sulfonate, and aryl ether derivatives, to afford allyltitanium compounds as depicted in Scheme 13.27 [57]. 

A reaction of an allylic compound containing a hydrogen to an alkene function is an ene reaction. Thus a reaction between propene and ethylene is an example of an ene reaction. 

Hiyama and coworkers produced the same allylation compounds via the in situ reaction of l,l-difluoro-3-(dimethylphenylsilyl)propene and aldehydes with catalytic tris(diethyl-aminojsulfonium difluorotrimethylsilicate (TASF) or potassium f-butoxide (equation 85)78-79. 

The two chlorinated propene compounds shown are colorless liquids with pungent, irritating odors. Allyl chloride is an intermediate in the manufacture of allyl alcohol and other allyl compounds, including pharmaceuticals, insecticides, and thermosetting varnish and plastic resins. Dichloropropene compounds have been used as soil fumigants, as well as solvents for oil, fat, dry cleaning, and metal degreasing. 

SYN 2-PROPENE-l-THIOL SAFETY PROFILE Poison by inhalation and ingestion. Strong irritant to skin and mucous membranes. When heated to decomposition it emits highly toxic fumes of SOx. Vet " dangerous fire hazard. To fight fire, use water mist or spray, alcohol foam, CO2, or dry chemical. See also ALLYL COMPOUNDS and MERCAPTANS. 

The reactions of allyliron tricarbonyl halides with donor molecules were studied. Triphenylphosphine substituted only one carbonyl, that trans-oriented with respect to the halogen of the form (XIX) [432). The phosphine derivatives of (XX) were not isolated as pure compounds. The complexes were decomposed entirely by dimethyl sulfoxide, giving [(0113)280] jFeX2 [435). Thermal decomposition of C3H5Fe(CO)3X depended on the medium and gave either diallyl, or diallyl ketone, together with propene, allyl ether, Fe(CO)5, and FeX2 [436). 

It is well known that silylation of allyl derivatives with vinylsilane catalyzed by a ruthenium hydride complex is accompanied by isomerization ofpropen-l-yl to propen-2-yl derivatives as well as homo-coupling of vinylsilane when equimolar amounts of the initial substances are used. If catalyst I was used in the SC of allyl amide and allyl amine with vinylsilanes, a S-fold excess of olefin to vinylsilane was used to stop homocoupling of vinylsilane, but simultaneously no more than 5% of isomerization of allyl compound was observed [19, 26]. When allyl boronate is used instead of allylamine under mild conditions (20 - 40 °C), the two reactions catalyzed by I and IV yield stereoselectively -product (see Scheme 4) [26]. 

The grafting of Mo(allyl)4 or other allyl compounds (Mb, W) on silica and other oxides has also been investigated, but the mechanism of grafting remains unclear [8]. These catalysts had some activity in olefin metathesis, but several activation steps under H2 and O2 at high temperature were usually needed to obtain the best activity. Iwasawa et al. [8] were able to establish a structure-activity relationship showing that Mo(IV) was the most active (Scheme 4 activity for propene metathesis at 90 °C in ton. min ). These steps, however, dramatically modified the coordination sphere of the metal, depending on the thermal treatment applied. 

Similar mixtures of hydrido-allyl compounds are obtained from complexes of 1-propene and 1-butene (Scheme 28), the difference being that discrete Tp Ir (alkene)2 complexes have not been isolated, only their hydridovinyl isomers. It is interesting to note that the analogous reaction of Tp IrH(CH = CH2) (rj - 2 -4) (203) affords (kinetically) the tethered butene complex Tp IrH ((7-7T-CH2CH2CH = CH2) (216, 80%, vide supra), and a small quantity of the hydrido-crotyl complex Tp IrH(f/ -C3H4Me) (217), which becomes the sole product upon prolonged heating (100 °C, 20 h). A series of related hydrido-allyl complexes (328-331) are obtained from ambient temperature photolysis of the 1,3-butadiene complexes 232-234 (Section III-B.2). 

To predict which of the various C—H bonds in propene is most likely to break when a mixture of propene and bromine or chlorine is heated, we need to look at bond dissociation enthalpies. We find that the bond dissociation enthalpy of an allylic C—H bond in propene (Table 8.7) is approximately 92 kj (22 kcal)/mol less than that of a vinylic C—H bond and 50 kJ (12 kcal)/mol less than a C—H bond of ethane. The allyl radical is even more stable than a 3° radical this unusual stability also applies to carbocations. The reason the allylic C—H bond is so weak is discussed in Section 8.6B. Note from Table 8.7 that the benzyl radical CgH5CH2- is stabilized in exactly the same way as the allyl radical and for the same reason benzylic compounds undergo many of the same reactions as allylic compounds (Section 21.5). 

From this value and known C—H bond dissociation energies, pK values can be calculated. Early application of these methods gave estimates of the p/Ts of toluene and propene of about 45 and 48, respectively. Methane was estimated to have a pAT in the range of 52-62. Electrochemical measurements in DMF have given the results shown in Table 7.3. These measurements put the pK of methane at about 48, with benzylic and allylic stabilization leading to values of 39 and 38 for toluene and propene, respectively. The electrochemical values overlap with the pATdmso scale for compounds such as diphenyl-methane and triphenylmethane. 

Bordwell and Cooper211 drew attention to the inertness of a-halosulfones and related compounds towards nucleophilic displacements of the halogen. Thus chloromethyl p-tolyl sulfone reacts with potassium iodide in acetone at less than one-fiftieth of the rate for n-butyl chloride. On the other hand, l-(p-toluenesulfonyl)-3-chloro-l-propene reacts about 14 times faster than allyl chloride. This contrast (and other comparisons) led the authors to attribute the inertness of a-halosulfones to steric hindrance, which was eliminated when the sulfonyl group was more remote from the reaction center. 

It can be the same with compounds with complex groups. The presence of another compound that is not unstable can increase or in some cases decrease the instability of a molecule. This can be observed if propene or 1-propanol are compared with allylic alcohol, for which behaviour is aggravated, compared with the first two compounds that each have one function only. 

The combination of 2-halomethyl-3-halo-l-propene with carbonyl compounds mediated by indium in water generated / /.v-allylation... 

The indium-mediated allylation carried out with allylstannanes in combination with indium chloride in aqueous medium was reported by Marshall et al.113 Allylindium was proposed as the reaction intermediate. Various aldehydes can be alkylated very efficiently with 3-bromo-2-chloro-l-propene mediated by indium in water at room temperature. Subsequent treatment of the compound with ozone in methanol followed by workup with sodium sulfite provided the desired hydroxyl ester in high yield.114... 

Acetylenic acrylates have been used to reduce side reactions in the preparation of acrylic sil(ox)anes by hydrosilylation [13,14], Allylic acrylates are known to result in addition products with both types of double bonds. Elimination of propene under loss of the allylic group is a major concern, because this path yields acryloxy silicone compounds with SiOC linkages of low hydrolytic stability. 

Transition metal alkyl compounds react with the -OH groups on the surface of silica in a manner similar to that described for the silanol [reaction (13)] and as with the latter more than one type of bonding is possible. Silica dried at 200°C reacts with Zr(allyl)4 to give two molecules of propene per metal atom and utilizing in the course of this process two -OH groups per metal atom. The chemistry of the process is accurately described by the equation... 

The addition of a large excess of bis(cj-alkenyl)zinc compounds to the TiC -catalyzed polymerization of propene resulted in an increased polymer yield, but a reduction in the molecular weights of the polymers.64 This suggests that the diorganozinc compounds are both co-catalysts and chain-transfer agents in this polymerization. The catalyst activity decreased in the order bis(3-butenyl)zinc < bis(7-octenyl)zinc < chlorodiethylaluminum. Bis(7-octenyl)zinc was co-polymerized with propene to afford hexylzinc side chains, whose zinc-carbon moieties were converted to vinyl groups by the addition of allyl bromide. 

The alkane propane has pATa 50, yet the presence of the double bond in propene means the methyl protons in this alkene have pATa 43 this value is similar to that of ethylene (pATa 44), where increased acidity was rationalized through sp hybridization effects. 1,3-Pentadiene is yet more acidic, having pATa 33 for the methyl protons. In each case, increased acidity in the unsaturated compounds may be ascribed to delocalization of charge in the conjugate base. Note that we use the term allyl for the propenyl group. 

An intermediate proposed to occur during the ammonoxidation of propene and that would correspond to the intermediate B suggested for the oxidation of propene is B as shown in Scheme 1. Compounds designed to model these intermediates structurally or functionally should contain a 7r-allyl-molybdenum group covalently bound to an imido ligand as a minimum requirement, ideally an 0x0 ligand should be bound in addition. 

Terminal olefins appear to be reactive only if they are not allylic in nature (e.g., styrene and 2,4,4-trimethyl-l-pentene). Allylbenzene (3-phenyl-l-pro-pene) is inert toward nitrosyl chloride, whereas propenylbenzene (1-phenyl-l-propene) reacts. The preparations are usually carried out at low temperatures. When molecular weights of the products are determined at 5°C, they correspond to dimeric structures. At the melting point of naphthalene, the products are predominantly monomeric. This observation is reasonably general for nitroso compounds [69]. 

The allylic oxidation of propene is catalyzed by (compound) metal oxides, which essentially contain metal ions of variable valency. It is commonly accepted that a redox mechanism is operative in such a way that the catalyst acts as the oxidizer and that lattice oxygen is incorporated in the oxidation products. The assumptions have been proved for several catalysts by the analysis of cation valency changes and by experiments with labelled oxygen. 

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