7. Terpenes consist of joined isoprene units (2-methylbuta-1,3-diene). They are classified by the number of isoprene units in the molecule. (a) Myrcene and humulene are terpenes present in hops which give beer its characteristic flavour and aroma. (i) Circle an isoprene unit on the myrcene structure below. (ii) Humulene has the molecular formula C15H24. Name the class of terpene to which humulene belongs. (b) Squalene, a triterpene, is included in some flu vaccines to enhance the body's immune response. A single dose of flu vaccine contains 10-69 mg of squalene. Calculate the mass of squalene required to produce a batch of 500,000 doses of flu vaccine. Your answer must be given in kg. (ii) Squalene is a fully saturated hydrocarbon used in skin moisturising cream. Squalene can be made by the reaction of squalene with hydrogen. (c) The monoterpene limonene, found in lemon oil, can be converted into the alcohol, terpineol. (i) Name the type of reaction taking place. (ii) When terpineol is heated with copper(II) oxide, no reaction takes place. Explain why no reaction takes place.

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7. Terpenes consist of joined isoprene units (2-methylbuta-1,3-diene) - Scottish Highers Chemistry - Question 7 - 2018

Question 7

7. Terpenes consist of joined isoprene units (2-methylbuta-1,3-diene). They are classified by the number of isoprene units in the molecule. (a) Myrcene and humulene... show full transcript

Worked Solution & Example Answer:7. Terpenes consist of joined isoprene units (2-methylbuta-1,3-diene) - Scottish Highers Chemistry - Question 7 - 2018

Step 1

Circle an isoprene unit on the myrcene structure.

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Answer

The isoprene unit in the myrcene structure can be identified as the repeating unit represented by a chain of five carbon atoms, typically denoted as:

ext{Isoprene unit: C}_5 ext{H}_8

Step 2

Name the class of terpene to which humulene belongs.

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Answer

Humulene belongs to the class of terpenes known as sesquiterpenes, which are characterized by having three isoprene units.

Step 3

Calculate the mass of squalene required to produce a batch of 500,000 doses of flu vaccine.

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Answer

To calculate the mass of squalene needed, we first convert the dose from mg to kg:

10.69 ext{ mg} = rac{10.69}{1000} ext{ g} = rac{10.69}{1000 imes 1000} ext{ kg} = 1.069 imes 10^{-5} ext{ kg}

Next, multiply by the number of doses:

ext{Total mass} = 500,000 imes 1.069 imes 10^{-5} ext{ kg} = 5.345 ext{ kg}

Step 4

State the number of moles of hydrogen needed to fully saturate one mole of squalene to produce one mole of squalane.

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Answer

To fully saturate one mole of squalene, six moles of hydrogen are needed, since each double bond requires the addition of one mole of hydrogen.

Step 5

Name the type of reaction taking place.

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Answer

The reaction taking place is an addition reaction, where elements or compounds are added to the unsaturated moiety of limonene to form terpineol.

Step 6

Explain why no reaction takes place when terpineol is heated with copper(II) oxide.

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Answer

No reaction occurs because terpineol is a tertiary alcohol, which cannot be easily oxidized. The steric hindrance and stability of the tertiary alcohol prevent it from undergoing further reaction with copper(II) oxide.

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7. Terpenes consist of joined isoprene units (2-methylbuta-1,3-diene) - Scottish Highers Chemistry - Question 7 - 2018

Worked Solution & Example Answer:7. Terpenes consist of joined isoprene units (2-methylbuta-1,3-diene) - Scottish Highers Chemistry - Question 7 - 2018

Circle an isoprene unit on the myrcene structure.

Name the class of terpene to which humulene belongs.

Calculate the mass of squalene required to produce a batch of 500,000 doses of flu vaccine.

State the number of moles of hydrogen needed to fully saturate one mole of squalene to produce one mole of squalane.

Name the type of reaction taking place.

Explain why no reaction takes place when terpineol is heated with copper(II) oxide.

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