Lactone Production via Low-Pressure Dehydration and Hydrogenation
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Solution Overview
Problem
Existing methods for producing 2-alkylcycloalkanones are inefficient due to multiple steps, low yield, and the difficulty in separating the aimed product from by-products, especially when high pressure is required for one-step dehydration and hydrogenation reactions.
Innovation Solution
A process involving the dehydration and hydrogenation of 2-(1-hydroxyalkyl)-cycloalkanones in a hydrogen gas flow under low pressure (20-200 kPa) with an acid and platinum group metal catalyst, followed by oxidation using percarboxylic acid to produce 2-alkylcycloalkanones with high yield and purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If dehydration and hydrogenation are carried out in one step under high pressure, then reaction rate is improved, but by-product formation increases and separation difficulty worsens
Solution Approach 1:
The patent divides the reaction process into two distinct steps: first dehydration to form 2-(alkylidene)-cycloalkanone, then hydrogenation to form 2-alkylcycloalkanone. This segmentation allows optimization of each step independently, preventing by-product formation that occurs in one-step high-pressure processes.
Solution Approach 2:
The dehydration reaction is performed first to create the intermediate 2-(alkylidene)-cycloalkanone, which is then subjected to hydrogenation. This preliminary action ensures that the carbonyl group is properly positioned before hydrogenation, preventing unwanted reduction of the carbonyl group that occurs under high-pressure one-step conditions.
2Object-generated harmful factors
If multiple steps are used for dehydration and hydrogenation, then by-product formation is reduced, but productivity deteriorates
Solution Approach 1:
The patent combines dehydration and hydrogenation into a sequential two-step process using the same catalyst system (acid catalyst followed by metal catalyst in the same solvent), eliminating the need for intermediate isolation and purification. This merging maintains high productivity while reducing by-products compared to traditional multi-step processes.
Solution Approach 2:
The reaction proceeds continuously from dehydration to hydrogenation without interrupting the reaction stream or requiring intermediate purification. The solvent system and catalyst configuration enable continuous transformation, maintaining high productivity while ensuring high purity through controlled reaction conditions.
3Manufacturing precision
If traditional two-step process is used, then yield is improved, but number of steps increases and complexity worsens
Solution Approach 1:
The patent uses the same solvent system and performs both dehydration and hydrogenation in sequence without intermediate workup or purification steps. This merging of operations maintains high yield while reducing the number of discrete steps and associated equipment complexity compared to traditional methods requiring separate purification stages.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process efficiently produces lactones with high yield and purity, suitable for perfume materials, while reducing costs and simplifying product separation.
Implementation Method 1
subjecting a 2-(1-hydroxyalkyl)-cycloalkanone to dehydration and hydrogenation reaction in a flow of a hydrogen gas under a pressure of from 20 to 200 kPa (absolute pressure) in the presence of an acid and a platinum group metal catalyst
Implementation Method 2
subjecting a 2-(1-hydroxyalkyl)-cycloalkanone to dehydration and hydrogenation reaction in a flow of a hydrogen gas under a pressure of from 20 to 200 kPa (absolute pressure)
Implementation Method 3
subjecting the 2-alkylcycloalkanone to oxidation reaction using a percarboxylic acid
Data Source
AI summary
The present invention relates to a process for producing 2-alkylcycloalkanones with a high yield and a high purity. In addition, the present invention also relates to a process for producing lactones as a useful perfume material for cosmetics, flavors, etc. More specifically, the present invention relates to a process for producing a 2-alkylcycloalkanone represented by the following general formula (2) which includes the step of subjecting a 2-(1-hydroxyalkyl)-cycloalkanone to dehydration and hydrogenation reaction in a flow of a hydrogen gas under a pressure of from 20 to 200 kPa (absolute pressure) in the presence of an acid and a platinum group metal catalyst; and a process for producing a lactone which includes the step of subjecting the 2-alkylcycloalkanone to oxidation reaction using a percarboxylic acid: wherein n is an integer of 1 or 2; and R1 and R2 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms with the proviso that R1 and R2 may form a ring through a carbon atom adjacent thereto.