8/18/2019 Haworthcx

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Drawing Haworth FormulaD-Glucose exists primarily as a cyclic hemiacetal

HCHO

OH

HHO

OHH

OHH

CH2OH

OOH

OH

HOHOHO O

HO

HOHOHO

OH

O

HO

OH

HO

HO

OH

O

HO

OH

HO

HOOH

Linear Form of D-glucoseFischer Projection

Cyclic formchair conformation

Haworth formula

=

CH2OH

CHO

H

OHH

OHOH

H

H

OH

OH

CHO

CH2OH

HH

OHOH

H

H

OH

=

1

2

3

4

5

6

1

23

4

5 6

1

23

4

5

6

1

23

4

5

6

1

23

4

5

6

123

45

6

123

45

6

Rules for converting a Fischer projection to a Haworthformula.1) Draw proper sized ring: pyranose = 6-memberedfuranose = 5-membered.

2) C-1 of the sugar (anomeric carbon) is always rightcorner of the ring. Number carbons clockwise aroundthe ring.3) D-sugar = CH2OH up; L-sugar = CH2OH down4) α has OH opposite to CH2OH; ß has OH same sideas CH2OH5) Other stereocenters: -OH right (R ) = down; -OH left

(S ) = up

α-D-glucopyranoseß-D-glucopyranose

OHH

HO H

HO H

CH2OH

CHO

HO

OHO

OHOH

ß-L-arabinofuranose

1

2

3

4

5

1

23

4

5

Example - L-arabinose toß-furanose form2 = R  = down3 = S  = up4 = S  = L = CH2OH down

Redrawing glucose helpsto see ring stereochemistry.

Formation of thehemiacetal gives a newstereocenter, theanomeric carbon (C-1).