13.6 - Cyanides and Isocyanides
Enroll to start learning
Youβve not yet enrolled in this course. Please enroll for free to listen to audio lessons, classroom podcasts and take practice test.
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Introduction to Cyanides and Isocyanides
π Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Today we'll discuss cyanides and isocyanidesβa fascinating pair of compounds that are important in organic chemistry. Can anyone tell me what a cyanide looks like?
Isn't it a structure with a carbon triple-bonded to nitrogen?
Exactly! We write it as RβCN. Now, what about isocyanides?
Isocyanides would have the nitrogen first, right? Like RβNC?
Correct! The way they bond distinguishes them. Remember, 'cy' in cyanide emphasizes 'carbon-nitrogen'. Let's remember that!
Can you elaborate on why that is important?
Sure! Their structures impact how they behave in reactions, which we'll cover next. Letβs summarize: cyanides involve a carbon triple-bond, while isocyanides have nitrogen at the forefront.
Preparation of Cyanides and Isocyanides
π Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Now, who can tell me how we prepare cyanides?
We can use potassium cyanide with an alkyl halide!
Exactly! The reaction is Alkyl halide + KCN β RCN. What about isocyanides?
Isocyanides use silver cyanide instead, don't they?
Yes! So our formula is Alkyl halide + AgCN β RNC. Rememberβwith potassium it's cyanide, with silver it becomes isocyanide. Now, can anyone give me an example?
What if I start with bromobutane to get butyronitrile?
Great example! Now letβs summarize this session: potassium cyanide creates cyanides and silver cyanide creates isocyanides.
Reactions of Cyanides and Isocyanides
π Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Letβs dive into the reactions! What happens when we hydrolyze cyanides?
They turn into carboxylic acids and ammonia!
Correct! The reaction we see is RCN + 2HβO + HβΊ β RCOOH + NHββΊ. And what about their reduction?
When reduced, they become primary aminesβlike making methanamine from methyl cyanide.
Exactly! RCN + 2Hβ β RCHβNHβ is the reduction reaction. When studying these, remember how the transformations take place: hydrolysis for acids, reduction for amines. Any questions?
What makes these reactions so significant?
Great question! Theyβre utilized to create important compounds in pharmaceuticals and agrochemicals. Letβs wrap up this session with a summary: hydrolysis leads to acids and reduction leads to amines!
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
Cyanides and isocyanides are organic compounds characterized by their unique carbon-nitrogen bonding. The section details their structural differences, methods of preparation, and key reactions such as hydrolysis and reduction, emphasizing their roles as essential intermediates in organic chemistry.
Detailed
Detailed Summary
Cyanides and isocyanides are two important classes of organic compounds featured in this section. They are distinguished by their bonding to nitrogen:
- Cyanides (RβCN) exhibit a carbon-nitrogen triple bond.
- Isocyanides (RβNC) have a nitrogen-carbon triple bond, thus reversing the position of carbon and nitrogen.
Preparation of Cyanides and Isocyanides
-
Cyanides can be synthesized via the reaction of an alkyl halide with potassium cyanide (KCN):
Alkyl halide + KCN β RCN -
Isocyanides are produced through the interaction of alkyl halides with silver cyanide (AgCN):
Alkyl halide + AgCN β RNC
Reactions
-
Hydrolysis of Cyanides: In an aqueous acidic medium, cyanides hydrolyze into carboxylic acids and ammonium ions:
RCN + 2HβO + HβΊ β RCOOH + NHββΊ -
Reduction of Cyanides: Cyanides can be reduced to primary amines when treated with hydrogen:
RCN + 2Hβ β RCHβNHβ
These reactions underlie the utility of cyanides and isocyanides in organic synthesis, including the synthesis of pharmaceuticals and agrochemicals, thereby establishing their significance in chemistry.
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Structure of Cyanides and Isocyanides
Chapter 1 of 3
π Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
- Cyanides (RβCN): Carbon-nitrogen triple bond.
- Isocyanides (RβNC): Nitrogen-carbon triple bond.
Detailed Explanation
Cyanides are compounds that contain a carbon-nitrogen triple bond, represented by the formula RβCN, where R is any alkyl or aryl group. This means that the carbon atom is triple-bonded to the nitrogen atom, creating a very strong connection. On the other hand, isocyanides have a nitrogen-carbon triple bond, represented as RβNC. Here, the nitrogen is bonded to the carbon with a triple bond. These structural differences significantly affect the properties and reactivity of the two types of compounds.
Examples & Analogies
Think of cyanides like a tightly-knit group of friends who are inseparable (the carbon-nitrogen triple bond), while isocyanides are like a different group that stays close but has a different dynamic (the nitrogen-carbon triple bond). Both groups are strong, but their connections and behaviors differ.
Preparation of Cyanides and Isocyanides
Chapter 2 of 3
π Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
- Alkyl halide + KCN β RCN (Cyanide)
- Alkyl halide + AgCN β RNC (Isocyanide)
Detailed Explanation
Cyanides can be synthesized by reacting an alkyl halide with potassium cyanide (KCN). In this reaction, the halide group of the alkyl halide is replaced by the cyanide group, forming a cyanide compound. Isocyanides are prepared by a similar method, where an alkyl halide is reacted with silver cyanide (AgCN). This substitution reaction also leads to the formation of an isocyanide.
Examples & Analogies
Imagine making a sandwich. For a cyanide, you take a piece of bread (alkyl halide), and replace the ham (halide group) with turkey (cyanide group) using KCN as your helper. For an isocyanide, you do something similar but use a different ingredient (silver cyanide) to replace the ham with chicken (isocyanide).
Reactions of Cyanides
Chapter 3 of 3
π Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
- Cyanides undergo hydrolysis:
- RCN + 2HβO + HβΊ β RCOOH + NHββΊ
- Reduction:
- RCN + 2Hβ β RCHβNHβ
Detailed Explanation
Cyanides can undergo hydrolysis, which is the reaction with water to produce a carboxylic acid and ammonium ion. In this reaction, two molecules of water and a hydrogen ion (HβΊ) interact with the cyanide, leading to the formation of RCOOH (a carboxylic acid) and NHββΊ (ammonium). Additionally, cyanides can be reduced, which means they can gain hydrogen to form primary amines. In this case, two hydrogen atoms are added to RCN, resulting in the formation of RCHβNHβ, a primary amine.
Examples & Analogies
Think of cyanides like a frozen food (RCN) that transforms into a meal when cooked (hydrolysis), producing a tasty dish (carboxylic acid) and a side of nutrients (ammonium). Meanwhile, the reduction reaction is like adding a bit of seasoning (hydrogen) to complement the dish, changing its flavor to make it more enjoyable (primary amine).
Key Concepts
-
Cyanides: Defined as organic compounds featuring a carbon-nitrogen triple bond.
-
Isocyanides: Defined as organic compounds with a nitrogen-carbon triple bond.
-
Preparation Methods: Cyanides are prepared using KCN; isocyanides use AgCN.
-
Reactions: Cyanides hydrolyze to form acids and can be reduced to primary amines.
Examples & Applications
Example of Cyanide: When 1-bromopropane reacts with KCN, it forms propionitrile (C2H5CN).
Example of Isocyanide: When 1-bromopentane reacts with AgCN, it forms pentyl isocyanide (C4H9NC).
Memory Aids
Interactive tools to help you remember key concepts
Rhymes
Cyanides are blue, with carbon and nitrogen too!
Stories
In the laboratory, a chemist found a single carbon held tightly to nitrogen. When he added the right reagents, it transformed, forming important syntheses, just like isocyanides in a mix with silver.
Memory Tools
Cyanides are 'C' with 'N' in the tight bond; Isocyanides have 'N' linked to 'C' beyond.
Acronyms
CuaNC
Cyanides (Triple bond Carbon-Nitrogen)
isouC
Flash Cards
Glossary
- Cyanide
An organic compound with a carbon-nitrogen triple bond, represented as RβCN.
- Isocyanide
An organic compound with a nitrogen-carbon triple bond, represented as RβNC.
- Hydrolysis
The chemical process that involves the breaking down of a compound by water.
- Reduction
A chemical reaction that involves the gain of electrons or a decrease in oxidation state.
Reference links
Supplementary resources to enhance your learning experience.