Why sucrose reacts rapidly with seliwanoffs

Here, we show an oxidative O -glycosylation reaction involving anomeric nucleophiles with alcohols and carboxylic acids resulting in exclusive anomeric selectivities. These reactions require a C2-coordinating group and open possibilities for the development of preparative oligosaccharide protocols capitalizing on orthogonal activation modes of anomeric nucleophiles with minimal protective group manipulations.

Furthermore, this method can serve as a complementary tool to classical O -glycosylation protocols and, given its mild conditions and ambient reaction temperatures, can be easily adapted to suit the needs of automated synthetic strategies.

For detailed synthetic procedures, see Supplementary Information. General procedure for anomeric acylation: Under N 2 , a one-dram vial was charged with anomeric stannane 0. The filtrate was concentrated and purified by column chromatography on SiO 2. General procedure for glycosylation with iodosobenzene: Under N 2 , anomeric stannane 0.

The reaction mixture was stirred at room temperature for the indicated period of time, filtered through a pad of silica gel, and concentrated. The crude material was purified by column chromatography on SiO 2. The reaction mixture was filtered through a pad of silica gel, and concentrated.

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Shi, L. A positive Seliwanoff's test is obtained with? Professor Sam. Apr 4, What are alkenes and alkynes used for? Why are alkenes and alkynes called unsaturated compounds?

Are all alkenes and alkynes unsaturated hydrocarbons? Why are alkenes and alkynes more reactive? These cultures are a lactose-positive, H2S-positive S. Hektoen enteric HE agar. Blue-green to blue colonies with or without black centers. Many cultures of Salmonella may produce colonies with large, glossy black centers or may appear as almost completely black colonies.

Xylose lysine desoxycholate XLD agar. Pink colonies with or without black centers. Bismuth sulfite BS agar. Brown, gray, or black colonies; sometimes they have a metallic sheen. Surrounding medium is usually brown at first, but may turn black in time with increased incubation, producing the so-called halo effect. HE and XLD agars. BS agar. Atypically some strains produce green colonies with little or no darkening of the surrounding medium. Lightly touch the very center of the colony to be picked with sterile inoculating needle and inoculate TSI slant by streaking slant and stabbing butt.

Without flaming, inoculate LIA slant by stabbing butt twice and then streaking slant. Since lysine decarboxylation reaction is strictly anaerobic, the LIA slants must have deep butt 4 cm. Cap tubes loosely to maintain aerobic conditions while incubating slants to prevent excessive H 2 S production. Salmonella in culture typically produces alkaline red slant and acid yellow butt, with or without production of H 2 S blackening of agar in TSI.

In LIA, Salmonella typically produces alkaline purple reaction in butt of tube. Consider only distinct yellow in butt of tube as acidic negative reaction. Do not eliminate cultures that produce discoloration in butt of tube solely on this basis. Some non- Salmonella cultures produce a brick-red reaction in LIA slants. Cultures that give an alkaline butt in LIA should be retained as potential Salmonella isolates and submitted for biochemical and serological tests if the TSI slant is either alkaline over acid or acid over acid.

Cultures that give an acid butt in LIA and an alkaline slant and acid butt in TSI should also be considered potential Salmonella isolates and should be submitted for biochemical and serological tests. Cultures that give an alkaline butt in LIA, but where there is no change in the TSI for both the slant and the butt should be discarded.

Test retained, presumed-positive TSI cultures as directed in D, below, to determine if they are Salmonella species, including S. If TSI cultures fail to give typical reactions for Salmonella alkaline slant and acid butt pick additional suspicious colonies from selective medium plate not giving presumed-positive culture and inoculate TSI and LIA slants as described in D-8 , above.

Apply biochemical and serological identification tests to:. If 3 presumptive-positive TSI cultures are not isolated from one set of agar plates, test other presumptive-positive TSI agar cultures, if isolated, by biochemical and serological tests.

Examine a minimum of 6 TSI cultures for each 25 g analytical unit or each g composite. Mixed cultures. Examine plates for presence of colonies suspected to be Salmonella. MacConkey agar. Typical colonies appear transparent and colorless, sometimes with dark center. Colonies of Salmonella will clear areas of precipitated bile caused by other organisms sometimes present. See D-7b , above. Urease test conventional. With sterile needle, inoculate growth from each presumed-positive TSI slant culture into tubes of urea broth.

Since occasional, uninoculated tubes of urea broth turn purple-red positive test on standing, include uninoculated tube of this broth as control. Optional urease test rapid. Transfer two 3-mm loopfuls of growth from each presumed-positive TSI slant culture into tubes of rapid urea broth. Discard all cultures giving positive test. Retain for further study all cultures that give negative test no change in color of medium. Perform the polyvalent flagellar H test at this point, or later, as described in E-4 , below.

Select 2 formalinized broth cultures and test with Salmonella polyvalent flagellar H antisera per manufacturer's instructions.

Place 0. Prepare saline control by mixing 0. Observe at 15 min intervals and read final results in 1 h. Nonspecific — agglutination in both test mixture and control. Test the cultures giving such results with Spicer-Edwards antisera. Statens Serum Institute Procedure. The Salmonella is grown over night on a non-selective agar medium. Swarm agar is the best suited medium for growing cultures for H typing, but H antigens can be serotyped from a non-selective agar medium if the H antigens are well expressed.

Add a small drop of antiserum approx. Transfer culture using an inoculating loop from several colonies to the drop of antiserum and mix well. The amount of culture should be sufficient to give a distinct milky turbidity.

Tilt the slide or petri dish for seconds. A positive reaction is seen as visible agglutination, whereas a negative reaction is seen as homogeneous milky turbidity. A late or weak agglutination should be considered negative. Physiological saline 0. Spicer-Edwards serological test. Use this test as an alternative to the polyvalent flagellar H test.

It may also be used with cultures giving nonspecific agglutination in polyvalent flagellar H test. Perform Spicer-Edwards flagellar H antisera test as described in E, 3b , above.

Perform additional biochemical tests E, 5a-c , below on cultures giving positive flagellar test results. If both formalinized broth cultures are negative, perform serological tests on 4 additional broth cultures E, 3a , above.

If possible, obtain 2 positive cultures for additional biochemical testing E, 5a-c , below. If all urease-negative TSI cultures from sample give negative serological flagellar H test results, perform additional biochemical tests E, 5a-c, below. Lysine decarboxylase broth. If LIA test was satisfactory, it need not be repeated. Use lysine decarboxylase broth for final determination of lysine decarboxylase if culture gives doubtful LIA reaction.

Inoculate broth with small amount of growth from TSI slant suspicious for Salmonella. Salmonella species cause alkaline reaction indicated by purple color throughout medium. Negative test is indicated by yellow color throughout medium. If medium appears discolored neither purple nor yellow add a few drops of 0. Phenol red dulcitol broth or purple broth base with 0. Inoculate broth with small amount of growth from TSI culture.

Most Salmonella species give positive test, indicated by gas formation in inner fermentation vial and acid pH yellow of medium. Production of acid should be interpreted as a positive reaction. Negative test is indicated by no gas formation in inner fermentation vial and red with phenol red as indicator or purple with bromcresol purple as indicator color throughout medium.

Potassium cyanide KCN broth. Transfer 3 mm loopful of 24 h tryptophane broth culture to KCN broth. Heat rim of tube so that good seal is formed when tube is stoppered with wax-coated cork. Interpret growth indicated by turbidity as positive. Most Salmonella species do not grow in this medium, as indicated by lack of turbidity.

Malonate broth. Transfer 3 mm loopful of 24 h tryptone broth culture to malonate broth. Since occasional uninoculated tubes of malonate broth turn blue positive test on standing, include uninoculated tube of this broth as control. Most Salmonella species cultures give negative test green or unchanged color in this broth.

Indole test. Transfer 5 ml of 24 h tryptophane broth culture to empty test tube. Most Salmonella cultures give negative test lack of deep red color at surface of broth. Serological flagellar H tests for Salmonella. If either polyvalent flagellar H test E-3 , above or the Spicer-Edwards flagellar H test tube test E-4 , above has not already been performed, either test may be performed here.

Discard as not Salmonella any culture that shows either positive indole test and negative serological flagellar H test, or positive KCN test and negative lysine decarboxylase test. Polyvalent somatic O test. Commercially available sectioned slides may be used. Emulsify 3 mm loopful of culture from h TSI slant or, preferably, tryptose blood agar base without blood with 2 ml 0. Add 1 drop of culture suspension to upper portion of each rectangular crayon-marked section.

Add 1 drop of saline solution to lower part of one section only. Add 1 drop of Salmonella polyvalent somatic O antiserum to other section only. With clean sterile transfer loop or needle, mix culture suspension with saline solution for one section and repeat for other section containing antiserum. Tilt mixtures in back-and-forth motion for 1 min and observe against dark background in good illumination.

Consider any degree of agglutination a positive reaction. Classify polyvalent somatic O test results as follows:. Negative — no agglutination in test mixture; no agglutination in saline control. Nonspecific — agglutination in test and in control mixtures. Perform further biochemical and serological tests as described in Edwards and Ewing's Identification of Enterobacteriaceae 2. Somatic O group tests. Test as in E-6a, above, using individual group somatic O antisera including Vi, if available, in place of Salmonella polyvalent somatic O antiserum.

For special treatment of cultures giving positive Vi agglutination reaction, refer to sec. Record cultures that give positive agglutination with individual somatic O antiserum as positive for that group. Record cultures that do not react with individual somatic O antiserum as negative for that group. Additional biochemical tests. Classify as Salmonella those cultures which exhibit typical Salmonella reactions for tests , shown in Table 1. If one TSI culture from 25 g analytical unit is classified as Salmonella , further testing of other TSI cultures from the same 25 g analytical unit is unnecessary.

Cultures that contain demonstrable Salmonella antigens as shown by positive Salmonella flagellar H test but do not have biochemical characteristics of Salmonella should be purified E-l , above and retested, beginning with E-2 , above. Perform the following additional tests on cultures that do not give typical Salmonella reactions for tests in Table 1 and that consequently do not classify as Salmonella.

Inoculate broth with small amount of growth from unclassified h TSI slant. Positive — acid production yellow and gas production in inner fermentation vial. Consider production of acid only as positive reaction. Most cultures of Salmonella give negative test result, indicated by no gas formation in inner fermentation vial and red with phenol red as indicator or purple with bromcresol purple as indicator throughout medium.

Discard as not Salmonella , cultures that give positive lactose tests, except cultures that give acid slants in TSI and positive reactions in LIA, or cultures that give positive malonate broth reactions.

Perform further tests on these cultures to determine if they are S. To intensify and speed reaction, add a few crystals of creatine. Read results after 4 h; development of pink-to-ruby red color throughout medium is positive test.

Most cultures of Salmonella are VP-negative, indicated by absence of development of pink-to-red color throughout broth. Simmons citrate agar. Inoculate this agar, using needle containing growth from unclassified TSI agar slant.