:"carbon"}],"connections":[{"to":"mech-nuc","from":"nuc","color":"teal","label":"nucleophile","style":"solid"},{"to":"mech-add","from":"carbon","color":"sky","label":"addition to double bond","style":"solid"}]},"order":2,"title":"Deduce the mechanism name","description":"By looking at the roles of the reactants, we deduce that the reaction is initiated by a nucleophile and leads to addition across a double bond."},{"type":"text","order":3,"title":"State the final answer","content":"Based on our deduction, the mechanism for the reaction between potassium cyanide and butanone is:\n\n**Nucleophilic addition**","highlights":[{"text":"Nucleophilic addition","location":"specification"}]}]}],"generatedAt":"2026-06-11T08:51:39.722Z","modelVersion":"gemini-3.5-flash","explanationVersion":"v2"},"options":[]},{"id":"26c510b1-4b7e-4c90-a850-d6000fcbd58f","label":"2","content":"The 2-hydroxy-2-methylbutanenitrile formed by the reaction is a mixture of equal amounts of two isomers.\n* State the name of this type of mixture.\n* Explain how the structure of butanone leads to the formation of equal amounts of these two isomers.\n* Draw 3D representations of the two isomers of 2-hydroxy-2-methylbutanenitrile to show the relationship between them.","markscheme":"- Racemic mixture (or racemate) B1\n- Planar carbonyl ($\\text{C}=\\text{O}$) group in butanone M1\n- Equal probability (or 50% chance) of attack by the nucleophile ($\\text{CN}^-$) from either side (above or below the plane) A1\n- Draws one 3D isomer with tetrahedral geometry around the chiral carbon, showing four distinct bonds to $-\\text{OH}$, $-\\text{CN}$, $-\\text{CH}_3$, and $-\\text{CH}_2\\text{CH}_3$ (or $-\\text{C}_2\\text{H}_5$) M1\n- Draws the second 3D isomer as a non-superimposable mirror image of the first, showing the relationship across a mirror plane A1","marks":5,"order":1,"markingRubric":null,"explanation":{"methods":[{"id":"direct","label":"Standard Chemical Analysis","steps":[{"type":"text","order":0,"title":"Name the Mixture","content":"A 50:50 mixture of two optical isomers (enantiomers) is called a **racemic mixture** (or **racemate**).\n\nThis occurs because the optical activities of the two enantiomers are equal and opposite, cancelling each other out and making the overall mixture optically inactive.","highlights":[{"text":"State the name of this type of mixture.","location":"specification"}]},{"type":"text","order":1,"title":"Identify the Carbonyl Geometry","content":"To understand how the equal amounts are formed, we need to look at the geometry of the starting material, butanone ($\\text{CH}_3\\text{COCH}_2\\text{CH}_3$):\n\n* The carbonyl carbon atom in the $\\text{C}=\\text{O}$ double bond is $sp^2$ hybridized.\n* Consequently, the carbonyl group has a **planar** (flat) geometry around the reaction center.","highlights":[{"text":"Explain how the structure of butanone leads to the formation of equal amounts of these two isomers.","location":"specification"}]},{"type":"text","order":2,"title":"Explain Nucleophilic Attack","content":"Because the carbonyl reaction center is planar, the incoming cyanide nucleophile ($\\text{CN}^-$) can attack from either side:\n\n* There is an **equal probability** (or a 50% chance) of the nucleophile attacking from **above** or **below** the flat plane.\n* Attack from the top face produces one enantiomer, while attack from the bottom face produces the other.\n* Since both pathways are equally favorable, a 50:50 (racemic) mixture is formed."},{"type":"text","order":3,"title":"Draw the 3D Isomers","content":"$40","highlights":[{"text":"Draw 3D representations of the two isomers of 2-hydroxy-2-methylbutanenitrile to show the relationship between them.","location":"specification"}]}]}],"generatedAt":"2026-06-11T08:52:05.899Z","modelVersion":"gemini-3.5-flash","explanationVersion":"v2"},"options":[]},{"id":"77fdc434-1bb8-42cf-b556-a5ecbcc78840","label":"3","content":"2-Hydroxy-2-methylbutanenitrile can be used in the synthesis of the monomer, 2-methy

Aldehydes and ketones (A-level only)

Question 9

Aldehydes and ketones (A-level only) Questions

Aldehydes and ketones (A-level only)

Question 9

Aldehydes and ketones (A-level only) Questions