	primary hydroxy groups	secondary hydroxy groups	tertiary hydroxy groups
number of groups in one molecule of V	Table answer r1_primary hydroxy groups	Table answer r1_secondary hydroxy groups	Table answer r1_tertiary hydroxy groups

4(a)(ii)Organic Functional Group TestsMedium2 marks

Complete Table 4.2 to show what is observed when separate samples of V are added to each reagent. State 'none' if no reaction occurs.

Reagent	Observation with V
$N a (s)$	Table answer na_Observation with V
2,4-dinitrophenylhydrazine (2,4-DNPH)	Table answer dnph_Observation with V
Fehling's reagent	none

4(a)(iii)Organic Functional Group TestsHard1 mark

Suggest why Fehling's reagent does not react with V but does react with aldehyde functional groups.

Answer

0 words

4(b)(i)AlcoholsEasy1 mark

Figure 4.1 is repeated for use in 4(b).

V is completely oxidised by heating under reflux with an excess of acidified

K_{2} C r_{2} O_{7} (a q)

to produce organic compound Z.

Describe the colour change in this reaction.

Colour of the mixture at the start of the reaction, and after the reaction

0 words

4(b)(ii)AlcoholsHard1 mark

Draw the structure of Z.

Draw with the mouse or a finger.

4(c)(i)Structural Geometric IsomerismEasy2 marks

Compounds W, X and Y are structural isomers of V.

Figure 4.2, the skeletal structures of the four structural isomers of V, labelled V, W, X and Y: V is (CH$_3$)(OH)C(CH$_2$OH)CH(OH)CH$_2$OH (a CH$_3$ and an OH on the same carbon, a CH$_2$OH branch, and a CH(OH)CH$_2$OH chain); W is HOCH(CH$_2$CH$_2$OH)CH(OH)CH$_2$OH (two carbons each bearing an OH, one carrying a CH$_2$CH$_2$OH branch, the other a CH$_2$OH branch); X is a central carbon bonded to an OH, two separate CH$_2$OH groups and a CH$_2$CH$_2$OH branch; Y is a central carbon bonded to four CH$_2$OH groups (fully symmetric, no CH$_3$ and no direct OH on the central carbon)

Describe structural isomerism.

Answer

0 words

4(c)(ii)Optical IsomerismHard2 marks

Identify which of structures V, W, X and Y show stereoisomerism. Explain your answer by referring to the relevant parts of the molecule that cause stereoisomerism.

Answer

0 words

4(c)(iii)Carboxylic Acids EstersHard1 mark

Y reacts with reagent R to produce compound E.

Figure 4.3, the reaction of isomer Y with reagent R to give compound E: Y is the symmetric central carbon with four CH$_2$OH arms, and E is the same central carbon with all four arms now esterified as -CH$_2$-O-CHO (a formate ester group, C(=O)H, on each arm)

Name reagent R.

4(d)(i)AlcoholsHard1 mark

Exactly

0.03 mol

of one of the isomers, V, W, X or Y, is completely oxidised by

0.08 mol

of acidified

K_{2} C r_{2} O_{7} (a q)

to produce only one organic compound with molecular formula

C_{5} H_{4} O_{8}

Identify which isomer, V, W, X or Y, is used in this reaction.

4(d)(ii)Oxidation Reduction Redox EquationsMedium1 mark

Complete the equation for this reaction.

3 C_{5} H_{12} O_{4} +__C r_{2} O_{7}^{2 -} +__H^{+} \to 3 C_{5} H_{4} O_{8} +__C r^{3 +} +__H_{2} O

The four missing coefficients, for

C r_{2} O_{7}^{2 -}

H^{+}

C r^{3 +}

and

H_{2} O

in that order, separated by commas