6-Organic-2 - 33rd IChO Problem 6 Student code Organic...

33rd IChO  Problem 6 Student code :
Official version
Organic chemistry of Indian spices
The rhizomes of ginger ( Zingiber officinale ) are well known for their medicinal and
flavoring properties. In Ayurveda (the traditional system of medicine in India),
different formulations of ginger are used for the treatment of gastrointestinal
problems, common cold and other ailments. Several compounds are responsible for
the pungency of ginger. Many are simple substituted aromatic compounds with
different side chains. Three of them, Zingerone, (+)[6] Gingerol (to be referred
hereafter as Gingerol only), and Shogaol are particularly important.
Zingerone C
11
H
14
O
3
Gingerol C
17
H
26
O
4
Shogaol C
17
H
24
O
3
6.1 Zingerone gives positive FeCl
3
and 2,4–DNP (2,4–dinitrophenylhydrazine)
tests. It does not react with Tollen’s reagent. Therefore, Zingerone contains
the following functional groups: [Mark X in the correct boxes.]
(a) alcoholic hydroxyl (e) ester
(b) aldehydic carbonyl (f) alkoxyl
(c) ketonic carbonyl (g) unsaturation
(d) phenolic hydroxyl
2 marks

33rd IChO  Problem 6 Student code :
Official version
Chemical shifts Multiplicity Relative intensity
(  )
2.04 singlet 3
2.69,271 two (closely spaced) triplets of equal intensity 4
3.81 singlet 3
5.90 broad singlet (D
2
O exchangeable) 1
6.4 – 6.8 two doublets with similar chemical shifts 3
and one singlet
Alkenes cis 5 – 14 Hz (commonly around 6 – 8 Hz)
trans 11  19 Hz (commonly around 14 – 16 Hz)
The data obtained from the 1 H NMR spectrum of Zingerone are shown in Table 1.