Carbon penultimate

Alternatively one chain radical may abstract a proton from the penultimate carbon atom of the other, giving one saturated and one unsaturated dead chain ... 

This mechanism differs from the "carbide theory in that chain growth involves oxygen-containing groups and is thought to take place on the ultimate or penultimate carbon atoms of the longest chain by surface condensation reactions. 

Radical addition to the penultimate carbon (exo attack) The solvent is unspecified. (Data from Beckwith, 1981)... 

Ordinarily, DCo(CO)4 would be expected to add to an olefin to an appreciable extent by anti-Markownikoff addition, since with olefins more straight chain than branched chain product results. Such addition would place deuterium on the penultimate carbon atom. It can be argued that allyl alcohol is not an olefin and therefore might be expected to behave differently. As usual more work is necessary. A similar isomerization of allyl alcohol to propanal using FelCO) has been reported by Emerson and Pettit (24). 

In Figure 2.14, it is implied that the terminal carbon atom can occupy any position on the rim of the cone that is, there is assumed to be perfectly free rotation around the penultimate carbon-carbon bond. This is equivalent to saying that all values of , the angle that describes the rotation (see Fig. 2.14), are equally probable. Any hindrance to free rotation will block certain configurations, expanding the coil dimensions still further. 

Pentobarbital is biotransformed by oxidation of the penultimate carbon of the methyl butyl side-chain to produce a mixture of alcohols, and by iV -hydroxylation. The alcoholic metabolites of pentobarbital are pharmacologically inactive. Approximately 86% of a radioactive dose is excreted in the urine in 6 days, about 1% as unchanged drug and up to 73% as the L- and D-diastereoisomers of 3 -hydroxypentobarbital in a 5.4 1 ratio, and up to 15% as JV-hydroxypentobarbital.9 None of these metabolites is eliminated as a conjugate. 

Figure III-2 Which pairs of sugars are enantiomers Diastereoisomers Epimers The stereochemistry of the penultimate carbon (boldface) determines whether the sugar belongs to the d family or the l family.

In cases in which ring formation involves an OH on a carbon other than the penultimate carbon (e.g., aldohexofuranoses), the remaining carbon atoms of the tail (e.g., CHOH)... 

More than three times as much as was obtained because free radicals tend to abstract a hydrogen atom attached to a penultimate carbon atom of an n-alkane more readily than one attached to a more internally-located carbon atom (see, for example, the results of the ethylation of n-heptane, Expt. 14). There are in pentane twice as many penultimate carbon atoms as the internally located carbon atom however, the more ready reaction at the penultimate carbon atom is confirmed by the products obtained with n-heptane. 

The reaction of isopentane with ethylene under the same conditions as those used for n -pentane resulted in about the same yield of heptanes (31%) and a very small amount of higher-boiling product (Expt. 11). The heptanes consisted of more than 6.5 times as much 3,3-dimethylpentane as 2,3-dimethylpentane. It may be concluded that abstraction of the single hydrogen attertiary carbon atom takes place much more readily than does abstraction of one of the two hydrogen atoms attached to the secondary (penultimate) carbon atoms. 

As indicated in the discussion of the reaction of n-pentane, ethylation of n -heptane took place chiefly at a penultimate carbon atom, yielding 3-methyloctane as the principal product only small amounts of 3- and... 

It may be concluded that ethylation of n-butyl chloride occurs most readily at the penultimate carbon atom and next most readily at the carbon atom holding the chlorine atom. It probably also occurs at the other primary carbon atom. 

Fried, Walz and Wintersteiner isolated 4-desoxy-i/-glycero-tetrose phenylosazone (XLII) from the reaction of streptobiosamine hydrochloride with phenylhydrazine and thus demonstrated that streptose was configurationally an l sugar. The levorotation ([a] o —37°, water ) of streptosonic acid monolactone (XXIII) might also be adduced as contributory evidence for the l configuration of the penultimate carbon of streptose, should Hudson s lactone rule be applicable to this rather complex structure. 

Alkyl or aliphatic carbon centers are subject to mixed-function oxidation. Metabolic oxidation at the terminal methyl group often is referred to as to oxidation, and oxidation of the penultimate carbon atom (i.e., next-to-the-last carbon) is called to - I oxidation." " The initial alcohol metabolites formed from these enzymatic to and to - I oxidations are susceptible to further oxidation to yield aldehyde, ketones, or ca xylic acids. Alternatively, the alcohol metabolites may undergo glucuronide conjugation. 

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