7. Taxol (and other)

Question 1

Taxol usage

Answer 1

Taxol is used for the treatment of breast, ovarian, lung, bladder, prostate, melanoma, oesophageal, as well as other types of solid tumour cancers.

Taxol was first isolated from the bark of the Pacific yew tree, [a slow-growing tree found only in the northwest region of America.]

Taxol is an anticancer drug used in chemotherapy. [It is classified as a plant alkaloid, a taxane and an antimicrotubule agent]

Question 2

Taxol sustainability issues

Answer 2

Concerns were raised about the yew tree population

The bark of the tree contains a very small amount of taxol

The process was non-renewable
The supply was limited

1kg of the bark resulted in 10g of taxol

Question 3

Taxol Solubility

Answer 3

Low solubility in water

administered via intravenous injection and works by slowing down the growth of cancer cells.

Solubility can be increased by dissolving in alcohol with polyoxyethylated (35) castor oil.

Question 4

Enantiomers

Answer 4

An enantiomer is one of two stereoisomers that are non-superimposable mirror images of each other.

Question 5

Explain how a polarimeter can be used to determine the relative proportion of two enantiomers [2]

Answer 5

Pure enantiomers rotate the plane of the plane-polarized light by equal angles in opposite directions

A polarimeter is a scientific instrument used to measure the rotation of plane-polarized light as it passes through an optically active substance.

[It determines the polarization properties of light beams and samples, providing information about the direction and extent of the polarized light rotation.]

Question 6

Chiral Auxilliary

Answer 6

• An optically active chiral auxiliary is added to the starting molecule to force the reaction to follow a certain path
  or
  -Auxiliary creates stereochemical condition necessary to follow a certain pathway / stereochemical induction

-Chiral intermediate forms only one isomer/enantiomer

• after the new chiral centre was created chiral auxiliary was removed to obtain the desired product

(Taxol has 11 chiral carbon atoms)

Question 7

Alpha Decay

Answer 7

Nucleus loses 2 protons & 2 neutrons (an alpha particle)

238 U 92 –> 234 Th 90 + 4 He 2

Question 8

Beta minus Decay
[Assume this one unless they ask]

Answer 8

Neutron transformed into a proton & electron ejected from nucleus

234 Th 90 –> 234 Pa 91 + 0 e -1

Question 9

Beta positive Decay

Answer 9

The proton transformed into a neutron & positron ejected from the nucleus

15 O 8 –> 15 N 7 + 0 e +1

Question 10

Gamma Decay

Answer 10

Nucleus moves from a higher state of energy to a lower state of energy
Happens due to the emission of high energy electromagnetic radiation

240 Pu 94 –> 240 Pu 94 + Gamma