L-Penten

Acyl halides are intermediates of the carbonylations of alkenes and organic-halides. Decarbonylation of acyl halides as a reversible process of the carbo-nylation is possible with Pd catalyst. The decarbonylation of aliphatic acid chlorides proceeds with Pd(0) catalyst, such as Pd on carbon or PdC, at around 200 °C[109,753]. The product is a mixture of isomeric internal alkenes. For example, when decanoyl chloride is heated with PdCF at 200 C in a distillation flask, rapid evolution of CO and HCl stops after I h, during which time a mixture of nonene isomers was distilled off in a high yield. The decarbonylation of phenylpropionyl chloride (883) affords styrene (53%). In addition, l,5-diphenyl-l-penten-3-one (884) is obtained as a byproduct (10%). formed by the insertion of styrene into the acyl chloride. Formation of the latter supports the formation of acylpalladium species as an intermediate of the decarbonylation. Decarbonylation of the benzoyl chloride 885 can be carried out in good yields at 360 with Pd on carbon as a catalyst, yielding the aryl chloride 886[754]. 

FLUORINECOMPOUNDS,ORGANIC - PERFLUOROEPOXIDES] (Vol 11) Perfluoro-4,5-epoxy-l-pentene [15453-08-4]... 

Newer developments involve poly(4-methyl-l-pentene) (TPX), PS or PPE blends, and block copolymers. 

The synthesis of isotactic polymers of higher a-olefins was discovered in 1955, simultaneously with the synthesis of isotactic PP (1,2) syndiotactic polymers of higher a-olefins were first prepared in 1990 (3,4). The first commercial production of isotactic poly(l-butene) [9003-29-6] (PB) and poly(4-methyl-l-pentene) [9016-80-2] (PMP) started in 1965 (5). 

Table 1. Physical Properties of 1-Butene and 4-Methyl-l-Pentene...

Metbyl-l-pentene [763-29-1] M 84.2, b 61.5-62", d 0.680, n 1.395. Water was removed, and peroxide formation prevented by several vacuum distns from sodium, followed by storage with sodium-potassium alloy. 

Chemical Designations - Synonyms 2,4,4-Trimethyl-l-pentene Chemical Formula ... 

Perfluoro-2 (1 ethyl 1 methylpropyl)-3-methyl-l-pentene, the major hex-amer of tetrafluoroethylene, reacts with sodium methoxide to yield an ester, whereas a stable crowded ketene is formed by reaction with sodium hydroxide [2d] (equation 23)... 

Isomerization of fluoroolefins by a shift of a double bond is catalyzed by halide 10ns [7] The presence of crown ether makes this reaction more efficient [74] Prolonged reaction time favors the rearranged product with an internal double bond (equations 3-5) Isomerization of perfluoro-l-pentene with cesium fluoride yields perfluoro-2-pentenes in a Z ratio of 1 6 [75] Antimony pentafluoride also causes isomenzation of olefins leading to more substituted products [76]... 

The two dimers of (CH3)2C=CH2 are formed by the mechanism shown in Figure 6.16. In step 1 protonation of the double bond generates a small amount of tert-butyl cation in equilibrium with the alkene. The car bocation is an electrophile and attacks a second molecule of 2-methylpropene in step 2, forming a new carbon-carbon bond and generating a carbocation. This new carbocation loses a proton in step 3 to form a mixture of 2,4,4-trimethyl-l-pentene and 2,4,4-trimethyl-2-pentene. 

In a typical example of the malonic ester synthesis, 6-heptenoic acid has been prepared from 5-bromo-l-pentene ... 

H2C=CHCH2CH2CH2Bt -I- CH2(COOCH2CH3)2 5-Bromo-l-pentene Diethyl malonate... 

The equilibrium between 2,3-dihydro-4-pyrones and l-penten-3,5-diones is a related process which can be pictured as involving a reaction with a cyclic 6-membered transition state (see Scheme 2). 

The extent of double-bond isomerization over homogeneous catalysts is influenced by choice of solvent. Saturation of the double bond in 4-(4-me-thoxyphenyl)-3-(2 nitro-4-methoxyphenyl)-l-pentene was achieved smoothly by reduction over RhCl(Ph3P)j in benzene wiihout any hydrogenation of the nitro function. If the solvent were benzene-ethanol, isomerization of the double bond to a conjugated position also occurred ihis styryl bond was inert to reduction under these conditions (77). 

Kennedy, J. P. and Johnston, J. E. The Cationic Isomerization Polymerization of 3-Methyl-1-butene and 4-Methyl-l-pentene. Vol. 19, pp. 57—95. 

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