Pentyl branches

Table 1 Number of methyl, ethyl, butyl and pentyl branches per 1000 C-atoms in un-aged polyethylene compared to polyethylene thermo-oxidised for 67 days at 50 °C and pre-oxi-dised polyethylene aged in sterile or biotic mineral medium for 67 days at 50 °C...

Thermolysis. Lower tetraalkyl titanates are reasonably stable and can be distilled quickly at atmospheric pressure. Protracted heating forms condensation polymers plus, usually, alcohol and alkene. Longer or more branched chains are less stable. Thus, tetra- -pentyl titanate [10585-24-7] can be distilled at 314°C and 101.3 kPa (1 atm), whereas tetra- -hexyl titanate [7360-52-3] must be distilled at below 18.7 kPa (140 mm Hg) and tetra- -hexadecyl... 

The direction of elimination is also affected by steric effects, and if both the base and die reactant are highly branched, steric factors may lead to preferential removal of the less hindered hydrogen. Thus, when 4-methyl-2-pentyl iodide reacts with very hindered bases such as potassium tricyclohexylmethoxide, there is preferential formation of the... 

If the alkyl substituent in a dialkyl substituted polysilane is either too short or is branched, it cannot pack properly to allow side chain crystallization, and hence, one would expect very different, properties from PDHS and its higher homologs. In order to study this possibility, we synthesized and characterized the di-n-butyl (PDBS), di-n-pentyl (PDPS) and di-5-methylhexyl polymers (PDMHS). 

The most widely used complexing agents are alcohols (butanol, n-propyl alcohol and n-pentyl alcohol1). Schoch33 now recommends the use of Pen-tasol, a commercial mixture of pentyl alcohols, for the first precipitation, and 1-butanol for recrystallizations. For com (maize) starch, this avoids contamination of the amylopectin with an intermediate fraction which is sufficiently linear to be precipitated with Pentasol and yet has a degree of branching which prevents complex formation with butanol. 

Three years later. List and coworkers extended their phosphoric acid-catalyzed dynamic kinetic resolution of enoUzable aldehydes (Schemes 18 and 19) to the Kabachnik-Fields reaction (Scheme 33) [56]. This transformation combines the differentiation of the enantiomers of a racemate (50) (control of the absolute configuration at the P-position of 88) with an enantiotopic face differentiation (creation of the stereogenic center at the a-position of 88). The introduction of a new steri-cally congested phosphoric acid led to success. BINOL phosphate (R)-3p (10 mol%, R = 2,6- Prj-4-(9-anthryl)-C H3) with anthryl-substituted diisopropylphenyl groups promoted the three-component reaction of a-branched aldehydes 50 with p-anisidine (89) and di-(3-pentyl) phosphite (85b). P-Branched a-amino phosphonates 88 were obtained in high yields (61-89%) and diastereoselectivities (7 1-28 1) along with good enantioselectivities (76-94% ee) and could be converted into... 

The groups attached to the principal chain are called substituents, and these may be simple or complex. Simple substituents are formed directly from parent hydrides when a simple substituent is itself substituted, it becomes complex as a consequence. Normal alkyl groups are simple substituents branched alkyl groups are complex substituents. However, as exceptions the names isopropyl, isobutyl, jec-butyl, tert-butyl, isopentyl, tert-pentyl and neopentyl are taken to refer to simple substituents. 

The hydroformylation reaction, also known as the oxo reaction, is used extensively in commercial processes for the preparation of aldehydes by the reaction of one mole of an olefin with one mole each of hydrogen and carbon monoxide. The most extensive use of the reaction is in the preparation of normal- and iso-butyraldehyde from propylene. The ratio of the amount of the normal aldehyde product to the amount of the iso aldehyde product typically is referred to as the normal to iso (N I) or the normal to branched (N B) ratio. In the case of propylene, the normal- and iso-butyraldehydes obtained from propylene are in turn converted into many commercially-valuable chemical products such as n-butanol, 2-ethyl-hexanol, trimethylol propane, polyvinylbutyral, n-butyric acid, iso-butanol, neo-pentyl glycol,... 

Figure 8.13 The two Shell-types of antiagglomerant. On the left is the water-soluble type, with one branch (Rj) containing 8-18 carbons. On the right is the oil-soluble type with two branches (Rj) with 8-18 carbons. The central atom is nitrogen or phosphorus, and the shorter branches (R2) are butyl- or pentyl-groups.

Branched saturated polyester from adipic acid, phthalic anhydride, neopentyl glycol and trimethyl olpropane was mixed with BPA/DC solution in 2-methoxyethanol/ xylene and diluted with ethyl acetoacetate. A thermohardening coating with high hardness and good adhesion on steel was obtained [136]. A similar coating composition consists of BPA/DC and a polyester from adipic and isophthalic acid, trimellitic anhydride, neo pentyl glycol and trimethylolpropane [137, 138]. 

Isopentyl group— An alkyl group with the molecular structure of -CH2CH2CH(CH3)2 and is identified as the pentyl derivative that has a methyl group (-CH3) branching from the end of a chain of four carbon atoms. 

The resorcinols used as starting materials in the present process are either resorcinol itself (III, R=H) or a 5-alkylresorcinol (III, R=alkyl). The alkyl group may have up to twelve carbon atoms and it may be either branched or straight-chained. Examples of such alkyl groups are methyl, ethyl, propyl, sec-butyl, pentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, l-ethyl-2-methylpropyl, isohexyl, heptyl, 1-methylhexyl, 1,2-dimethylhexyl, 1,2-dimethylheptyl, 1-methyloctyl, and 1-methylnonyl. 

For skeletal rearrangements over zeolite, the nonclassical protonated cyclopropane intermediate could account for the experimental observations. Theoretical studies of the reaction mechanism indicated that protonated cyclopropane-type species do not appear as intermediates but rather as transition states. Considering all zeolite-catalyzed hydrocarbon reactions (hydride transfer, alkylation, disproportionation, dehydrogenation), only carbocations in which the positive charge is delocalized or sterically inaccessible to framework oxygens can exist as free reaction intermediates. In theoretical studies on the mechanism of the superacid-catalyzed isomerization of n-alkanes (ab initio and DFT calculations), protonated cyclopropanes were found to be transition states for the branching of both the 2-butyl cation and the 2-pentyl cation. ... 

List and coworkers reported an excellent approach to the enantioselective synthesis of P branched a amino phosphonates, which involved the extension of the dynamic kinetic resolution strategy (Scheme 3.53) [110] that was previously applied to the enantioselective reductive amination of a branched aldehydes by his research group (see Scheme 3.45). The method combines dynamic kinetic resolution with the parallel creation of an additional stereogenic center. They successfully accomplished the direct three component Kabachnik Fields reaction of 1 equiv each of the racemic aldehyde, p anisidine, and di(3 pentyl)phosphite in the presence of newly developed chiral phosphoric acid It. The corresponding p branched a amino phosphonates were obtained in high diastereo and enantioselectivities, especially for the aldehydes bearing a secondary alkyl group at the a position. 

Ryan WJ, Banner WK, WUey JL, Martin BR, Razdan RK (1997) Potent anandamide analogs the effect of changing the length and branching of the end pentyl chain. J Med Chem 40 3617-3625... 

Rearrangement of the carbon chain occurs easily when halogen (X) is substituted for OH in much-branched primary alcohols or secondary alcohols having a tertiary H atom in the -position tertiary halides are formed preferentially, e.g., ter t-pentyl bromide is the main product from neopentyl alcohol ... 

Reactants with longer aliphatic chains give products containing branched-chain substituents, even when the starting material is a straight-chain alkyl halide pure compounds are obtained only when the alkyl group of the halide is maximally branched, as in the production of ter/-pentylbenzene from benzene and terf-pentyl chloride. 

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