SYSTEMIC APPROACH TO TEACHING AND LEARNING HETEROCYCLIC

CHEMISTRY (SATLHC)

2008

A. F. M. Fahmy, M. A. El-HashashFaculty of Science, Department of Chemistry and Science

Education Center, Ain Shams University, Abbassia, Cairo, EGYPT

E-mail:fahmy@online.com.eg

W.A.Abduo National research Center ,Cairo,Egypt

The linear representation (1a) Vis systemic representation (1b) of concepts.

Fig: 1a concept concept concept concept concept concept concept concept

Fig: 1b

concept concept

concept concept

concept concept

concept concept

Systemic Teaching Strategy: we started teaching of any unit by Systemic diagram (SD0) that has determined the starting point of the unit, and we ended with a final systemic diagram (SDf) and between both we crossover several Systemics(SD1,SD2,...)

SD0 SDf

SD2SD1

Fig (2): Systemic teaching strategy

SATLHC

Pure Applied

- Synthesis- E-Substitution- Nu-Substitution- Addition- Cycloaddaition- Ring Opening- Het. Int. Conversion

- Pharmaceuticals- Food Additives- Plant growth regulators- Insecticides- Herbicides- Corrosion Inhibitors- Super conductors.- Dyes- Photographic materials etc..)

[LATLHC]

Z

Het.

X

Z

Het. Y

Z

Het.

E

Z

Het.F X,Y,E,F

[SATLHC]

Z = N, O, S

(Functional Groups)

Z

Het.

Application of SATL In Heterocyclic Chemistry:

A course on heterocyclic chemistry using

the SATL technique was organized and

taught to 3rd year students at Ain Shams

University. A portion of the one-semester

course (10 lectures, 20 hours) was taught to

students during the academic years.

1999/2000, 2000 / 2001, and 2003 / 2004

Linear VS Systemic Study in Heterocyclic Chemistry:

Linear study in heterocyclic chemistry means servay study on the reactivity of the heterocycles to give products in a separate chemical reactions (Alkylation, acylation, Nitration, Sulphonation, formylation, …..).

Systemic study in heterocyclic chemistry means servay study on the reactivity of both heterocycles and substituents and their all possible chemical relations.

Heteroatom: [(Z) = NH, O, S]

Substituents:[(G) = R, - CH2 - X, - X, -CH2 - OH - NH2, - CHO, - COR, - COOH]

GReactivity of the Nucleus

Reactivity of the Substituents

Z

Figure 3: summarizes comparative reactivites of

the five membered heterocycles Z

as model heterocyclic compounds, and

their possible relations.

Z CHO

ZRZ CO2H

Z

Z

O

OZ

O

Z N2Ph

Z NO2

ZBr

Z SO3H

Z COCH3

DMF/ POCl3

Z = NH, O (heat)Z = S (Cu/quinoline)

anhydride(Z = O,S)

Maletic

red. (Z = O, NH)

Z = NH, (RMgX)(Z = O,S) alkene/

H3PO4

Z = NH,

i) CH3CONR2/POCl3

ii) aq Na OAc

Z = NH (NBS)Z = O Br2/dioxanZ = S Br2/ AcOH

Z = NH, O, C6H5N-SO3

Z = S H2SO4

Z = NH, O, SAcONO2/

Ac2O

PhN2

Z = NH

+

Z CH2OH

HCHO/base(Z = NH)

Z = NH, O, S

The diagram (4) represents the reactivity of heterocyclic nucleus, and gives the linear separated chemical relations between (pyrrole, furan, thiophene), and their compounds.

We use heterocyclic chemistry to illustrate, again, how a subject can be organized systemically. SD1 summarizes the comparative reactivities of both heterocyclic nucleus and substituents.

Z CHO

ZRZ CO2H

Z

Z

O

OZ

O

Z N2Ph

Z NO2

ZBr

Z SO3H

Z COCH3

Oxidation

Wolff/Kishener

reducation

DMF/ POCl3

Z = NH, O (heat)Z = S (Cu/quinoline)

anhydride(Z = O,S)

Maletic

red. (Z = O, NH)

Z = NH, (RMgX)(Z = O,S) alkene/

HPO4

Z = NH,

i) CH3CONR2/POCl3ii) aq Na OAc

Z = NH (NBS)Z = O Br2/dioxanZ = S Br2/ AcOH

Z = NH, O, C6H5N-SO3

Z = S H2SO4

Z = NH, O, SAcONO2/

Ac2O

PhN2Z = NH

+

(4)

(5)

(6)

(7)SD 1

?

??

?

Z CH2OH

HCHO/base(Z = NH)

(3)?

?

(1)

?

(2)

In the systemic diagram (SD1) there are

unknown chemical relations (1-7) between

heterocyclic compounds.

These relations will be clarified later during

the study of pyrrole, furan and thiophene.

ASSESSMENT – ION SD1

ASSESSMENT – ION SD1

QI) Draw systemic diagrams illustrating the chemical relations between compounds in each of the following sets.

Z CHO Z COOHZ

1) ,, (Clockwise)

Z CHO Z COOHZ

2) ,,

Z R

,

A I - 1

Z COOH Z CHO

Z

OxidK2Cr2O7 / H2SO4

i)DMF, POCl3

ii)AcONaZ= O,NH heat 200oCZ =S Cu/Quinoline

QII) Complete the following systemic diagrams:

Z

(Z = NH)

....................

.......... ..........

1)

Z

..........

..........

..........

CHO

i) DMF /POCl3

ii)aq. Na2CO3

CH3MgX

(Z = .......)

2)

A II - 2

Z Z CH3

Z CHOi) DMF/ POCl3

ii) Na2CO3

Wolf-Kishner reduction

CH3MgX

(Z = NH)

Reactions of pyrrole, and Pyrrole compounds(asExample)Reactions of pyrrole, and Pyrrole compounds(asExample)

I-Pyrrole: (Prerequisites SD1)I-Pyrrole: (Prerequisites SD1)

We can summarize the reactions of pyrrole in the following diagram (Fig. 4).

NH

HN

i) DMF/POCl3

ii) aq. Na2CO3

HN

HN

Ac2O-10C

AcONO2PhN2

THFNBS

red.

(NH4)2CO3130cSealed Vessel

CO2NH4

+ -

+ -

BrHN

N2 PhHN

NO2

HN

HN

ii)HCl

NaOH

RMgX

i) C6H5NSO3

i) RCONR2

ii) NaOAc

COR

SO3HHN

RHN

CH2OHHN

Cl

N

CHO

H2/Rany Ni

N

CH2Cl2

CH3Li /

+

CHCl3/baseHCHO

The diagram (Fig. 4) represents the reactivity

of (pyrrole nucleus), and gives the linear

separated chemical relations between pyrrole

and its compounds.

We can illustrate the chemical relations in

(Fig. 4) systemically by modification of SD1 to

SD2 (Z = NH):

HN

HN

N

HN

HN

HN

N

H

HN

R=CH3

(1)

(3)CHO

Cl

?

?

ReductionOxid.

R=CH3base

HCHO

130ocbaseCHCl3/

i)DMF/POCl3

ii) aq.Na2CO3

RMgX

(2)(4)

(5)

Ac2O,-10oc

AcONO2

+PhN2

N2Ph

heat200oC

(8)

?

?

?

?

R

CH2OH

NO2

Br

SO3H

COR`

i) R`CONR2/POCl3

ii) NaOAc

i) C6H5NSO3

ii) HCl

?

H

?

HN

NH

CO2NH

4

CH2Cl2/

CH3Li

(NH4)2CO3

N COOH

NBS/THF

(6)

(7)

+ -

N

N

Wolff/ Kishner

red.

SD 2SD 2

Systemic diagram (SD2) shows know chemical relations between pyrrole and its compounds.

We have the unknown chemical relations between pyrrole compounds (1-8), and should be clarified during the study of pyrrole compounds.

After Study of pyrrole compounds [G = R, CH2OH, CHO, RCO, COOH , NH2):We can modify (SD 2 to SD 3) by adding chemical relations (1 – 7).

HN

H

N

HN

HN

NH

HN

CHOCl

Oxid

CH2O/

NaOH

baseCHCl3/

AlkylationRMgx

Wolff-kishner

red.

Nitration

Ac2O-10C

AcONO2

+PhN2

R = CH3

Oxid., chromic acid

heat200c

CH2OH

rearang.

Curtius

redNO2

SO3H

i) R`CONR2/POCl3

ii) aq. Na2CO3

i) C6H5NSO3

ii) HCl

aq. alkaline KMnO4

i) DMF/poCl3;

ii) aq Na2 CO3

HN

HN

(NH4)2CO3

hydroCO2NH4

NH

COR`

HN CHBr2

Diborane

R=CH3 NBS,CHCl3refulx

R=CH3

(R= CH3) hydrolysis

H2/PdR= CH3

NaBH4

HN

HN

HN

Ag2CO3/CeliteLTA/AcOH,

PhN2

CO2H

N2Ph NBS/THF

CON3

HN

pyridne

SOCl2/

NaN3

COClN

NH2

HNH

bromination Br

CH2Cl2 / CH3Li

150-200C

NN

H2-Rany Ni

R

KMnO4

Va p.

Pha se

de

car

bon

yla

tion

SD 3SD 3

+

ASSESSMENT – IION SD3

ASSESSMENT – IION SD3

QI) Draw systemic diagrams illustrating the chemical relations between compounds of each of the following sets:

(clockwise)NH

NNH

COOH CHO

,,1-

H

NH

,,,NO2

NH

COOH NH

CHONH

2-

H H HH

N

,,,N N N2PhNCOONH4 COOH

3-

A I - 1

NH

NH

CHO

NH

COOH

aq. alk.200oC

heatKMnO4

i)DMF, POCl3

ii) aq. Na2 CO3

QII) Complete the following systemic diagrams:

1-

NH

COOH

Ac2O- 10CAcONO2/

curtiusrearrangementSOCl2

200cheat

NaN3

....................

..................

..........

.......... ..........

2-NH

NH

NH

DMF , POCl3

aqNa2CO3

aq.alk.KMnO4

CHO

COOH

.........

.........

.........

.........

.........

Then give the systemic chemical relations in a list

A II - 2

NH

NH

aq. alk. KMnO4

bromination

COOH

NH

NH

CHO

Br

NBS, THF

Vap. phasedecarbonylation

i) DMF, POCl3

ii) Na2 CO3

heat,200c

Above chemical relations in a list:

NH

NH

NH

COOHCHO

NH

NH

NH

BrCOOH

NH

NH

NH

COOHCHO

NH

NH

NH

COOHNH

CHO Br

QIII) Arrange the following compounds in the right places in the following (SD.):

CH3NH

N,,

HNH

CHO

N,

HNH

COOH NO2

CH3 MgX

LTA/ AcOH

Oxidalk. KMnO4

........ ........

........

................

........

........................

QIV) How can you make the following conversions:

1) Pyrrole to pyrrole -2-carboxylic acid.

2) 2-Hydroxymethylpyrrole to 2-phenylazopyrrole.

3) Pyrrole -2-carboxylic acid to 2-bromopyrrole.

4) 2-Methylpyrrole to pyridine.

5) 2- Formyl pyrrole to 2-Nitropyrrole.

6) Pyrrole -2- Carboxylic acid to 2-aminopyrrole.

A IV - 2

NH

NH

COOH PhN2 N2Ph+

NH

NH

CH2OH

Diborane

CH3

Chromicacid

A IV - 4

NH

CH3

LTA/Acetic

NH

CHO

Vap. Phase

NH

CH2Cl2/CH3Li

N

QV) Rearrange the compounds in the following SD to give correct chemical relations:

NH

COOH NH

NH

NBS/THF

COONH4 NH

Brhydrolysis

(NH4)2 CO3/130C

Seald vesselBr2

200Cheat

AV)

NH

COOH

NH

NH

NBS/THF

COONH4

NH

Br

hydrolysis

(NH4)2 CO3/130C

Seald vesselBr2

200Cheat

QVI) Which of the following systemics are true and which are fals:

NH

NH

COOH NH

CHO

( )

i) DMF/ POCl3

ii) aq. Na2CO3

heat 100oC

aq. alk.KMnO4

NH

CHO

NH N

HCH3

( )

i) DMF/ POCl3

ii) aq. Na2CO3

Wolff.kishner

red

i) CH3 MgBrii) hydro.

a) b)

A VI) a: (x); b: () c: (x); d: ()

NH CO2H

NH

N2Ph NH

( )

heat 100oC

NH

CHO

NH

NH

CH2OH

( )

i) DMF/ POCl3

ii) aq. Na2CO3

i) CH2O/ii) NaOH

NaBH4

PhN2

+

PhN2

+

d)c)

QVII) Put () Infront of the correct systemics:

A VI) a: (x); b: (x) c: (); d: (x)

The systemic diagram represents the correct chemical relations between pyrrole and its compounds is one of the following:

NH

NH

COOH NH

CHO

( )

i) DMF/ POCl3

ii) aq. Na2CO3

heat 100oC

aq. alk.KMnO4

NH

CHO

NH N

HCH3

( )

i) DMF/ POCl3

ii) aq. Na2CO3

H2/Pd

i) CH3 MgBrii) hydro.

a) b)

NH CO2H

NH

NO2NH

( )

heat 200oC

NH

CHO

NH

NH

CH2OH

( )

i) DMF/ POCl3

ii) aq. Na2CO3

i) CH2O/ii) NaOH

NaBH4

Conc. HNO3

d)c)

H3SO4

Nitration

1- Heterocyclic derivative to another Hetercyclic derivative:

X

G

X

YHet. Het.

Example:

Z Br

H2SO4

Z SO3H

H2SO4

Z COCH3

(Z = O, S)

Systemic Teaching Strategies For Uses Of Heterocycles In Synthesis

2- Aliphatic compound to another aliphatic compound via Heterocycle:

Aliphatic compound

Aliphatic compound

ToToX

OH Cl

OHO

NH3

OH NH2

SR

S S R

Red.ii) BR3

i) Bun-Li

RanyNi

3- Heterocycles to homocycles:

X

Het. HO

S

Benzynee.g.

O

O

CH3CH3

OH

OHCH3

KOH

O O R

RR RC C

R = (Si (CH3)3)

Conclusion: After the experimentation of SATLHC in Egypt we

reached to the following conclusions:

1) SATLHC improved the students ability to view (HC) from a more global perspective.

2) SATLHC helps the students to develop their own mental framework at higher-level cognitive processes (application, analysis, and synthesis).

3) SATLHC increases students ability to learn subject matter in a greater context.

4) SATLHC increases the ability of students to think globally.

References:(1) Taagepera, M.; Noori, S.; J. Chem. Educ. 2000, 77, 1224.

(2) Fahmy, A. F. M.; Lagowsik. J. J.; J. Chem. Educ. 2003, 80, (9), 1078.

(3) Fahmy, A. F. M., El-Shahaat, M. F., and Saied, A., International Workshop on SATLC, Cairo, Egypt, April (2003).

(4) Fahmy, A.F.M., Lagowski, J.J.; Systemic Approach in Teaching and Learning Aliphatic Chemistry; Modern Arab Establishment for printing, publishing; Cairo, Egypt (2000).

(5) Fahmy A. F. M., El-Hashash M., Systemic Approach in Teaching and Learning Heterocyclic Chemistry. Science Education Center, Cairo, Egypt (1999).

(6) Fahmy A. F. M., Hashem, A. I., and Kandil, N. G.; Systemic Approach in Teaching and Learning Aromatic Chemistry. Science, Education Center, Cairo, Egypt (2000).

(7) Fahmy, A. F. M.; Hamza M. S. A; Medien, H. A. A.; Hanna, W. G., M. Abedel-Sabour; and Lagowski; J. J.; Chinese J. Chem. Edu., 23 (12) 2002, 12, 17th IEEC, Beijing August (2002).