Concept explainers
Interpretation:
The structure of L-(+)-threose and L-(+)-erythrose is to be represented and the aldotriose, which must be used for the preparation of the above-mentioned compounds in the Kiliani-Fischer synthesis, is to be determined.
Concept Introduction:
▸ The Kiliani-Fischer reaction is used for increasing the number of carbon atoms of an aldose molecule, as a result of the formation of the epimeric aldonic acid.
▸ It is an effective and economic process for the synthesis of monosaccharides by the process of hydrolysis of a cyanohydrin.
▸ Furthermore, it can also be used for the production of epimers of higher aldoses from a lower aldose, that is, a single aldose produces a mixture of two diastereomeric sugars called epimers.
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Organic Chemistry
- The following observations are obtained after a D-hexose was made to react with several reagents: (1) The reactions of a D-hexose with (a) to (d) below yields an aldaric acid (a) NH₂OH, (b) (CH3CO)₂O, NaOCOCH 3, and, (c) NaOCH3, and then, (d) HNO3, H₂O (2) HNO3 oxidation of the same D-hexose gives an aldaric acid. Predict the structures of the three (3) possible hexoses that can undergo the above reactions?arrow_forwardGive the products of periodic acid oxidation of each of the following. How many moles of reagent will be consumed per mole of substrate in each case? (a) d-Arabinose (b) d-Ribose (c) Methyl β-d-glucopyranosidearrow_forwardIdentify monomeric and multimeric (di-,tri-meric, for example) saccharides from this group. If you come across multimeric polypeptides, state the mono- mers that form these multimers. State the nature of the bond that links two units together in each case. (a) Maltose (b) Trehalose (c) Lactose (d) Sucrose (e) Cellobiose (f) Agarosearrow_forward
- (a) Isoleucine has been prepared by the following sequence of reactions. Give the structure of compounds A through D isolated as intermediates in this synthesis.(b) An analogous procedure has been used to prepare phenylalanine. What alkyl halide would you choose as the starting material for this synthesis?arrow_forward(i) Acetylation of glucose with acetic anhydride gives glucose pentacetate. Write the structure of the pentacetate. (ii) Explain – Why glucose pentacetate does not react with hydroxylamine?arrow_forwardPredict the products obtained when d-galactose reacts with each reagent.(a) Br2 and H2O (b) NaOH, H2O (c) CH3OH, H + (d) Ag(NH3) 2+ -OH(e) H2, Ni (f) excess Ac2O and pyridine (g) excess CH3 I, Ag2O (h) NaBH4(i) Br2, H2O, then H2O2 and Fe2(SO4)3 (j) (1) KCN/HCN; (2) H2, Pd/BaSO4; (3) H3O! (k) excess HIO42arrow_forward
- Aldohexoses A and B both undergo Ruff degradation to give aldopentose C. On treatment with warm nitric acid, aldopentose C gives an optically active aldaric acid. B alsoreacts with warm nitric acid to give an optically active aldaric acid, but A reacts to givean optically inactive aldaric acid. Aldopentose C is degraded to aldotetrose D, whichgives optically active tartaric acid when it is treated with nitric acid. Aldotetrose D isdegraded to (+)@glyceraldehyde. Deduce the structures of sugars A, B, C, and D, and useFigure 23-3 to determine the correct names of these sugars.arrow_forwardThere are three (3) vials labeled A, B, and C known to contain the following monosaccharides. All three samples reduce Tollens and Fehling. By oxidation with dilute HNO3 an optically active aldaric acid is obtained for sample A and the remaining two give products without optical activity. When the three samples were subjected to an alkaline medium, it was observed that, after a certain time, samples A and C reached the same value of the specific rotation [α]. Select the RIGHT alternative: (a) Sample A is Galactose. (b) Sample B is Alosa. (c) Samples A and C are not related to each other by an epimerization process. (d) Sample C is Talose. (e) Samples B and C are epimers.arrow_forwardGiven the following structure of aldose, (a) how many chiral carbons are there? (b) is it a reducing sugar? and (c) is it an L or D sugar?arrow_forward
- When the gum of the shrub Sterculia setigera is subjected to acidic hydrolysis, one of the water-soluble components of thehydrolysate is found to be tagatose. The following information is known about tagatose:(1) Molecular formula C6H12O6(2) Undergoes mutarotation.(3) Does not react with bromine water.(4) Reduces Tollens reagent to give d-galactonic acid and d-talonic acid.(5) Methylation of tagatose (using excess CH3 I and Ag2O) followed by acidic hydrolysis gives1,3,4,5-tetra-O-methyltagatose.(a) Draw a Fischer projection structure for the open-chain form of tagatose.(b) Draw the most stable conformation of the most stable cyclic hemiacetal form of tagatosearrow_forward(1) what reagent is used to convert p-amino phenol to quinone (2) Draw two different kekule's structures for pyrene and under line the more stablearrow_forward4(a) Suggest a test you will use to show that a given food substance contains protein.(b)Show how you will use(i)Modified Gabriel’s Synthsis(ii)Streckers’s Synthesis to prepare phenylalanine in the laboratory.arrow_forward
- Macroscale and Microscale Organic ExperimentsChemistryISBN:9781305577190Author:Kenneth L. Williamson, Katherine M. MastersPublisher:Brooks Cole