Alkyl branched

Esters Saturated Aryl and a,/3-unsaturated Diesters Oxalates Phthalates C=C—CO—o— Carbamates 1741-1725 1727-1714 1763-1761 1738-1728 1716-1708 1694-1688 Alkyl branching on carbon adjacent to C=0 lowers frequency by 5-15 cm k... 

Although /3-oxidation is universally important, there are some instances in which it cannot operate effectively. For example, branched-chain fatty acids with alkyl branches at odd-numbered carbons are not effective substrates for /3-oxidation. For such species, a-oxidation is a useful alternative. Consider phy-tol, a breakdown product of chlorophyll that occurs in the fat of ruminant animals such as sheep and cows and also in dairy products. Ruminants oxidize phytol to phytanic acid, and digestion of phytanic acid in dairy products is thus an important dietary consideration for humans. The methyl group at C-3 will block /3-oxidation, but, as shown in Figure 24.26, phytanic acid a-hydroxylase places an —OFI group at the a-carbon, and phytanic acid a-oxidase decar-boxylates it to yield pristanie add. The CoA ester of this metabolite can undergo /3-oxidation in the normal manner. The terminal product, isobutyryl-CoA, can be sent into the TCA cycle by conversion to succinyl-CoA. 

V. Karl, H-G. Schmair and A. Mosandl, Simultaneous stereoanalysis of 2-alkyl-branched acids, esters and alcohols using a selectivity-adjusted column system in multidimensional gas cliromatography , 7. Chromatogr. 587 347-350(1991). 

Stereoanalysis of 2-alkyl-branched acids, esters and alcohols in apple aroma concentrate... 

K. Rettinger, V. Karl, H.-G. Schmarx, E. Dettmar, U. Hener and A. Mosandl, Chirospeciflc analysis of 2-alkyl-branched alcohols, acids and esters chirality evaluation of 2-methylbutanoates from apples and pineapples , Phytochem. Anal. 2 184-188 (1991). 

V. Karl, J. Gutser, A. Dietrich, B. Maas and A. Mosandl, Stereoisomeric flavour compounds. EXVIII. 2-, 3- and 4-alkyl-branched acids. Part 2 chirospeciflc analysis and sensoT y evaluation , Chirality 6 427 - 434 (1994). 

By designing the repeat unit into the parent diene (containing either an alkyl branch or functionality), only a single type of repeat unit is formed upon polymerization, giving pure polymer microstructures. To date, perfectly controlled ADMET ethylene copolymers have included ethylene-CO,34 ethylene-vinyl alcohol,35 ethylene-vinyl acetate,36 and ethylene-propylene.20 Figure 8.12... 

The catalytic single-step Alfen process has a good space-time yield, and the process engineering is simple. The molecular weight distribution of the olefins of the single-step process is broader (Schulz-Flory type of distribution) than in the two-step Alfen process (Poisson-type distribution) (Fig. 2). As a byproduct 2-alkyl-branched a-olefins also are formed, as shown in Table 6. About... 

In the hydroformylation of an olefin not only are aldehydes formed that directly correspond with the used olefin isomer but also all the other theoretically possible isomeric 2-alkyl-branched aldehydes [49] ... 

A great portion of the formed 2-alkyl-branched alcohols, especially in the hydroformylation products of n-a-olefins, consists of the low-branched 2-methyl alcohols (Fig. 4). 

Performing this reaction in presence of metals like copper or nickel (Raney nickel)—especially in the case of lower molecular weight alcohols (C6-C10)— a dehydrative process occurs, the so-called Guerbet condensation reaction. Two alcohol molecules react to a 2-alkyl-branched isoalcohol ... 

The apparent necessity of a second signal for haustorial initiation provides another possibility for chemical control. Riopel and coworkers (2,12-14) observed a few years ago that gum tragacanth, a foliar extract, was a very potent haustorial initiator. Two active compounds were isolated (Xenognosin A shown below, and a flavonoid with similar structure). The structural features required for haustorial formation include a meta relationship of hydroxyl and methoxyl groups and an alkyl branching ortho to the methoxy substituent. 

The typical chemical shift for primary n-alkyl fluorides is -219, but the values for primary alkyl fluorides vary between -212 for ethyl fluoride and -226 for 2-ethyl-l-fluorobutane (Scheme 3.1). As mentioned above, alkyl branching leads to shielding of fluorine nuclei. 

Mitsubishi has patented a triphenylphosphine oxide-modified rhodium catalyst for the hydroformylation of higher alkenes with both alkyl branches and internal bonds. [19] Reaction conditions are 50-300 kg/cm2 of CO/H2 and 100-150 degrees C. The high CO/H2 partial pressures provide stabilization for rhodium in the reactor, but rhodium stability in the vaporizer separation system is a different matter. Mitsubishi adds triphenylphosphine to stabilize rhodium in the vaporizer. After separation, triphenylphosphine is converted to its oxide before the catalyst is returned to the reactor. 

Polyacetylenes are the most important class of synthetic polymers containing conjugated carbon-carbon double bonds. Some optically active monomers have been used with the following conclusions. Polymers of 1-alkynes having a branched side-chain assume in solution a helical conformation. A chiral side-chain induces a predominant screw sense in these helices. In particular, for alkyl branching, it has been shown that (S) monomers lead to a left-handed screw sense. 

Refsum s disease is an autosomal recessive peroxisomal disorder characterized by accumulation of phytanic acid and other 3-alkyl-branched fatty acids [55]. Patients develop hypertrophic demyelinative polyneuropathy, retinitis pigmentosa, ichthyosis and deafness. The disorder can be successfully treated by institution of a diet poor in phytanic acid, in conjunction with plasmapheresis to remove circulating phytanic acid. 

It is also common and correct to name amines with each alkyl branch listed as an attachment before the suffix -amine. In this system of nomenclature, the molecules in Figure 1.16 are ethylamine, methyl ethyl amine, and methyl diethyl amine. Several other methods of naming amines exist, but they will not be covered in this course. 

The two stereoisomeric 2-alkyl branched 2-alkenyl potassium species obtained upon deprotonation of ( )- and (Z)-isocaryophyllene equilibrate to afford an endo-exo... 

A C1215 essentially linear primary alcohol ethoxylate having an average of 9 ethylene oxide (EO) units per mole of alcohol (C12.15LPAE-9). The alcohol was prepared from Ci i.u olefins using catalytic addition of CO and H2. Approximately 80% of this alcohol contained linear alkyl chains. The 20% remaining contained 2-alkyl branches, mostly methyl. 

The extension of this reaction to nitromethane homologues was an obvious development, since it would provide a simple route for the simultaneous introduction of a nitro (or amino) function and an alkyl branch into a carbocyclic or pyranoside ring, to give compounds of type 2 and 3 respectively, that are as yet otherwise inaccessible. 

The common names of primary amines consist of the name of the alkyl branch followed by the name amine. The systematic (lUPAC) name of primary amines consists of the name of the alkane with the -e replaced by the suffix -amine. Some examples of primary amines appear in Figure 13-1. If more than one amine group is present, you need to use the appropriate prefix. 

Ultralinear polyethylene (ULPE) has recently become available through the use of soluble stereoregulating catalysts. Along with a decreased amount of short-chained alkyl branching, ULPE has a narrower molecular weight spread. 

Since the presence of small amounts of alkylated (branched) products can distort molecular weights, NMR spectroscopy was used to analyze the PSt content and the molecular weight of the PSt blocks. Molecular characteristics of select samples obtained by GPC, NMR, and conversion are summarized in Table 3. The Mj of PIB stars determined by GPC (LLS) were slightly higher than theoretical. This M and the mole fraction of St obtained by NMR spectroscopy were used to calculate the M of PSt segments and the PSt content in star... 

The relative sensitivity of short-chain alkyl branches of different sizes to elimination on irradiation with formation of the corresponding alkane has been variously reported as being constant or varying (13,14). Figure 9 compares G values for formation of the alkane corresponding to the short-chain branch from samples of these three polymers with branch frequencies from 0.5 to 6 per 1,000 C atoms. There is a notably higher scission efficiency for ethyl branches. 

Eq. 14 is the result of analysis for 53 compounds (4) having such diverse substituents as alkyl, branched alkyl, alkoxy, branched alkoxy, acyl, N02, CN, SR, S02R, halogen and CF3 at o-, m- and p-positions. 

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