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CHEM1611 2014-J-8 June 2014 • the Open Chain Form of D-Mannose Has

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CHEM1611 2014-J-8 June 2014 • the Open Chain Form of D-Mannose Has CHEM1611 2014-J-8 June 2014 Marks The open chain form of D-mannose has the structure shown. • 6 Draw the Haworth projection of β-D-mannopyranose. Draw the major organic product of the reaction of D-mannose with the following reagents. What is a reducing sugar? A sugar that reduces Tollens’ or Fehling’s reagent. Sugars containing aldehyde or hemiacetal groups are reducing sugars. ANSWER CONTINUES ON THE NEXT PAGE CHEM1611 2014-J-8 June 2014 Give the Haworth formula of a non-reducing disaccharide that yields D-mannose as the only product on acid hydrolysis. CHEM1611 2013-J-9 June 2013 Marks Consider the following two monosaccharides, (A) and (B). • 6 β-D-altropyranose α-D-xylofuranose Draw Fischer projections of the open chain forms of (A) and (B). (A) (B) Draw the major organic product of the reaction of D-altropyranose with the following reagents. Draw the Haworth stereoformula of a non-reducing disaccharide formed from (A) and (B). O CHEM1611 2012-J-9 June 2012 Marks The open chain form of D-talose is in equilibrium with two pyranose forms (L) and • 7 (M). Draw Haworth projections of (L) and (M). (L) (M) D-talose Give the Haworth stereoformula of one of the products obtained when D-talose is treated with excess methanol in the presence of an acid catalyst. Concentrated HNO3 oxidises aldehydes and primary alcohols to carboxylic acids, but does not oxidise secondary alcohols. Treatment of either D-talose or the aldohexose D-altrose with concentrated HNO3 gives the diacid (N). Give the Fischer projection of D-altrose. (N) Draw the Haworth stereoformula of a non-reducing disaccharide formed from D-talose. CHEM1611 2010-J-10 June 2010 Marks • Consider the following two monosaccharides, ( L) and ( M). 8 CH2OH CH2OH O O H OCH H OH H 3 H OH H OH H HO H (L) HO H (M) H H OH OH methyl β-D-glucopyranoside β-D-glucopyranose Describe a chemical test that could be used to distinguish ( L) from ( M). Include in your answer, the reagent you would use, what would be observed and a chemical equation that explains what is occurring in the reaction. + – Tollens reagent, [Ag(NH 3)2] /OH . This will give no reaction with (L), but will oxidise (M). In the process, the + [Ag(NH 3)2] ion is reduced to metallic Ag which deposits as a silver mirror. Give the reagents to convert ( L) to a H+/H O/heat mixture of ( M) and the α-anomer of ( M). 2 + Give the reagents to convert ( M) to ( L). excess CH 3OH / H catalyst Give the structure of the isomer of ( L) also produced in the preceding reaction. Sugar ( M) exists in equilibrium with an open chain form. Give the Fischer projection of this open chain form. List the functional groups present in ( L). primary and secondary alcohol, acetal CHEM1611 2010-J-10 June 2010 CHEM1611 2010-J-11 June 2010 • Marks Tuftsin is a tetrapeptide (Thr-Lys-Pro-Arg) produced by enzymatic cleavage of the 6 Fc-domain of the heavy chain of immunoglobulin G. It is mainly produced in the spleen and its activity is related primarily to immune system function. O H H N N 2 N OH O O O NH tuftsin NH NH2 HO HN NH2 Draw the Fischer projections of the four L-amino acids that result from the acid hydrolysis of tuftsin. COOH H2N H CHEM1611 2009-J-10 June 2009 Marks • Shown below are the Haworth structure of β-D-mannopyranose and the Fischer 8 projection of D-galactose. CHO H OH HO H CH2OH O OH HO H OH HO H OH HO CH2OH β-D-mannopyranose D-galactose Draw structures for the following sugars. Fischer projection of D-mannose Haworth structure of α-D-galactopyranose CHO HO H CH2OH HO O HO H OH H OH OH H OH HO CH2OH Give the product(s) obtained when D-mannose is treated with acidified methanol. CH OH 2 CH2OH O OCH3 O OH HO + OH HO HO HO OCH3 ANSWER CONTINUES ON THE NEXT PAGE CHEM1611 2009-J-10 June 2009 Draw the structure of any non-reducing disaccharide formed from D-mannose and D-galactose, indicating the configurations at the anomeric carbon atoms. Any one of the following 4 structures . CH2OH CH OH HO O 2 α HO O OH OH α HO HO O CH2OH CH2OH O O OH HO α OH HO β HO HO O CH OH CH OH O 2 2 O HO O OH HO α OH β HO HO O CH2OH HO CH2OH O O OH β OH HO β HO HO How many different non-reducing disaccharides can be formed from D-mannose and D-galactose? What is the relationship between any two of these compounds? 4 diastereomers CHEM1611 2008-J-5 June 2008 • Marks Complete the following table. 4 CONSTITUTIONAL REAGENTS/ STARTING MATERIAL FORMULA(S) OF MAJOR CONDITIONS ORGANIC PRODUCT(S) O OH O OCH2CH3 CH CH 3CH 2OH / 3 OH CH3 OH catalytic H + OH OH OH OH CO2 O OH HO H CH 3 OH H OH [Ag(NH3)2] / OH OH H OH OH HO H CH3 CHEM1611 2007-J-12 June 2007 Marks • Consider the following two disaccharides A and B. 6 CH2OH CH2OH O H H O H H H H OH OH OH OH HO OH H H O O H H H O H O H H H H HOH C HOH2C CH OH 2 CH2OH 2 OH OH OH OH A B Classify each disaccharide as “reducing” or “not reducing”. A: not reducing (no hemiacetal) B: reducing (hemiacetal present) Both these disaccharides hydrolyse to give tagatose and mannose. Mannose is an aldohexose. Draw the Fischer projections of the open chain forms of mannose and tagatose. Fischer projection of mannose Fischer projection of tagatose CHO CH2OH HO H O HO H H OH H OH H OH H OH HO H CH2OH CH2OH Mannose is classified as an aldohexose. What classification is given to tagatose? ketohexose Specify the above mannose as D-mannose or L-mannose. D-mannose Specify the above tagatose as D-tagatose or L-tagatose. L-tagatose CHEM1611 2006-J-10 June 2006 Marks • Consider the following two monosaccharides A and B. 7 CH2OH CH2OH OH HO O H O H OH H H H H OH H H H OH OH OH A: α-D-galactopyranose B: β-D-ribofuranose Give the Fischer projections of the open chain form of A and B. Fischer projection of D-galactose Fischer projection of D-ribose CHO CHO H OH H OH HO H H OH HO H H OH H OH CH2OH CH2OH Give the products obtained when D-ribose is treated with the following reagents. Acidified methanol NaBH 4 in methanol solvent CH2OH CH OH CH OH 2 H 2 OCH O O 3 H OH H H and H H H OH H OCH H H 3 H OH OH OH OH OH CH2OH CHEM1611 2006-J-10 June 2006 Draw the Haworth structure of a non-reducing disaccharide, which yields D-galactose and D-ribose on acid hydrolysis. CH2OH OH O H H OH H H H OH O CH2OH O H H H H OH OH CHEM1611 2005-J-10 June 2005 Marks An important group of oligosaccharides is the blood group antigens. The blood group 6 antigen of humans with blood group B can be represented by the partial structure below, in which R is a glycoprotein. CH2OH R HO O O H CH OH 2 O H HO O H H H H O OH H H H O H OH H OH H H H H H3C OH OH The type B blood group antigen can be hydrolysed to galactose (2 mole equiv.), fucose (1 mole equiv.) and a glycoprotein unit. Specify the fucose unit in the type B blood group pyranose antigen as a furanose or a pyranose. Specify fucose as a hexose, a pentose or a tetrose. hexose Give the Fischer projections of the open chain form of galactose and fucose. Fischer projection of galactose Fischer projection of fucose CHO CHO H OH HO H HO H H OH HO H H OH H * OH HO H CH2OH CH3 On your Fischer projection of galactose indicate with an asterisk (*) the carbon atom used in the D/L convention. Specify the galactose from blood antigen as D-galactose or L-galactose. D-galactose Specify the fucose from blood antigen as D-fucose or L-fucose. L-fucose CHEM1611 2004-J-9 June 2004 Marks The stucture of D-mannose is shown below. Draw the Fischer projection of 10 L-mannose in the space provided. CHO L-mannose HO H CHO HO H H OH H OH H OH D-mannose H OH CH OH 2 HO H HO H CH2OH D-Mannose is in equilibrium with two cyclic pyranose forms. Give the Haworth projection of these two cyclic forms. CH2OH CH2OH O O OH OH OH OH OH OH OH OH -anomer -anomer Give the products obtained when D-mannose is treated with the following reagents. methanol / H [Ag(NH3)2] /OH solution 1. NaBH4 2. dilute acid CH2OH CH2OH CO2 O HO H HO H OH OH HO H HO H OH OCH3 H OH CH2OH H OH O OCH3 H OH H OH OH OH CH2OH CH2OH OH ANSWER CONTINUES ON THE NEXT PAGE CHEM1611 2004-J-9 June 2004 Draw the Haworth structure of a reducing disaccharide, which, on acid hydrolysis, yields D-mannose as the only product.
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