Keto groups, free

Kaempferol glucoside 323 a-Keto acids 249, 262, 372 3-Ketobetulic acid 59 7-Ketocholesterol 60 Ketoglutaric acid 45, 249 Keto groups, free 273 Ketohexoses 180,181 Ketone peroxides 368 Ketones 72... 

Free aldehyde and keto groups [1 — 3] e.g. in aldoses and ketoses... 

The 1,5 relationship between the olefin and keto groups in 13 satisfies the structural prerequisite for the oxy-Cope transform,11 and, like the first synthesis of periplanone B by Still,9 Schreiber s strategy recognizes that an anionic oxy-Cope rearrangement could provide a powerful and direct method for the assembly of cyclode-cenone 13. On the basis of the model study described previously, it was projected that deprotonation of the free hydroxyl group in 14... 

The degree of linkage of a compound may also affect its bioaccessibility in the gut. It is generally admitted that a compound linked with other molecules (e.g., via esterification, glycosylation, etc.) is not absorbed as well as its free form and thus it must be hydrolyzed in the gut in order to be taken up by enterocytes. Due to the presence of hydroxyl or keto groups on their molecules, the xanthophylls (lutein, zeaxanthin, and P-cryptoxanthin) are found in both free and esterified (monoester or diester) forms in nature, but few studies have been conducted to date to assess the bioavailabilities of these esters. 

In an optimally controlled process free from transition-metal ions hydrogen peroxide bleaching is remarkably safe, there being no reported detrimental effects of bleaching at around 100 °C or for more than several hours [143]. Under such conditions, most of the peroxide appears to be consumed in the oxidation of chain end units of the cellulose macromolecule. The other major effect on the substrate is oxidation of secondary hydroxy to keto groups, accompanied by the formation of very few aldehyde or carboxyl groups [235]. 

There are at least ten forms in an aqueous solution of D-n7w-hexos-3-ulose,37 of which eight have been identified. Most forms have a free or a hydrated keto group at 23 °, there is 44% of the a-furanose and 1.5% of its hydrate 22% of the -pyranose and 12% of its hydrate 5% of the a-pyranose and 2% of its hydrate, 1% of a bicyclic y -furanose, and 8% of a dimer. The... 

Possibilities include (a) the hydrolysis of the lignin-carbohydrate bond by small amounts of water present in the wood despite all precautions to make the system anhydrous, (b) the dehydration of carbohydrates under these conditions to produce water and hence hydrolytic conditions, (c) transacetalization of the extracting acetal with carbohydrates to liberate alcohol and create conditions of alcoholysis, and (d) transacetalization of the extracting acetal with free or bound keto groups in the wood to liberate acetone and create conditions of acetonolysis. 

The a-keto acids are not present as such in the alkaloids as no free keto group can be detected. It was thus assumed that an a-hydroxy-a-amino acid group was present in the alkaloids, which would decompose to the corresponding a-keto acid and 1 equivalent of NH3 (82, 86). 

Keto group reduction, hydroxy construction On ACP, so never free. 

Free neuraminic acid, having a free 2-keto group and an amino group on C-5, has the same tendency toward formation of a nitrogen-containing, 5-membered ring. N-(Benzyloxycarbonyl)neuraminic acid (108a) is prepared by the condensation of 2-[(benzyloxycarbonyl)-... 

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