Drawing and naming the alcohols

5 marks · Hard

The molecule with the structural formula CH3CH2CH2OH is an alcohol.

(a)

State the IUPAC name for this alcohol.

[1 mark]

(b)

Justify your answer by explaining the naming process step by step, referring to the features of the molecule.

[4 marks]

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

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(a) propan-1-ol

(b) — · must show Recognition of 3-carbon straight chain, Identification of the –OH on the end carbon, Use of the suffix –ol, Use of number 1 for the –OH position, Explanation that 'prop' = 3 carbons, 'an' = saturated chain, 'ol' = alcohol

Also accept: propanol

Common mistakes: Incorrect carbon count; Omitting position number when required; Using common names instead of IUPAC

Show mark scheme and worked solution

Marking points

A1 (a) · 1 mark · State correct IUPAC name: propan-1-ol ('propanol' accepted)

M1 (b) · 1 mark · Identify and state number of carbon atoms as 3 ('prop')

M2 (b) · 1 mark · Identify presence and correct position (1) of the –OH group

M3 (b) · 1 mark · State and explain the suffix 'ol' is due to the alcohol functional group

M4 (b) · 1 mark · Mention 'an' for single bonds (saturation)

Worked solution

a) The IUPAC name is propan-1-ol. ('Propanol' is also accepted.)

b) Explanation:

- The molecule contains 3 carbon atoms in a straight chain, so the root name is 'prop'.

- The –OH group is attached to the end (first) carbon atom; the number 1 indicates its position.

- The suffix 'ol' indicates the molecule contains an alcohol functional group.

- The 'an' part shows that the chain is saturated (single bonds between carbon atoms).

So, the molecule is named propan-1-ol or propanol.