Title: A process for recovery of benzoic acid from benzoylation reaction.
Field of the invention:
The present invention relates to an economical process for recycling of benzoic acid from
benzoylation reaction.
Background of the invention:
Benzoic acid (Formula-I), also known as aromatic hydroxy acid is used in various fields like
medicine, dye carriers, plasticizers, preservatives and other spices and food production, alkyd
paint performance improvements. In chemistry, benzoic acid is the key material for
benzoylation reaction. Benzoic acid having a benzene or formaldehyde odor scaly or needlelike
crystals, melting point 122.13 ° C, and boiling point of 249 ° C, It is slightly soluble in
water, soluble in alcohol, ether and other organic solvents. Its molecular formula is C7H6O2,
and relative molecular mass of 122.1214.
Or*-
Formula-I
Benzoic acid is produced commercially by partial oxidation of toluene with oxygen. The
process is catalyzed by cobalt or manganese naphthenates. The process of preparing benzoic
acid requires the use of heavy metal cobalt or manganese as a catalyst. In the cause of the
heavy metal pollution also increases the cost.
Thus there is a requirement of recovery of benzoic acid with the help of green chemistry. The
present invention provides recovery process for benzoic acid by applying green chemistry.
Green chemistry is an important concept to the waste management industry because it
focuses on reducing the amount of waste created instead of simply focusing on how to handle
waste that has already been created. Due to this focus, green chemistry helps with source
reduction, which is when products are designed, manufactured, packaged, and used in a way
that limits the amount or toxicity of waste created.
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The first goal of source reduction is to reduce the overall amount of waste that is produced.
The second goal is to conserve resources by not using raw, virgin materials. In other words,
by following source reduction, fewer raw materials will have to be used to produce products.
Green chemistry supports source reduction because it reduces the overall amount of
hazardous substances used, which leads to a decrease in the hazardous waste produced and
the need for raw materials to make hazardous substances.
Green chemistry seeks to reduce the use of energy and resources, reduce waste, eliminate
costly treatments, produce safer products and improve competition in the marketplace. The
philosophy is that it's better to be proactive in the prevention of waste than to react after
development. The principles and framework for this approach include using benign
substances instead of toxic ones, using fewer materials and natural resources whenever
possible, using renewable materials, designing for energy efficiency, and planning for end of
product life by using recyclable or biodegradable materials.
12 principles of Green Chemistry:
1.Prevention
It is better to prevent waste than to treat or clean up waste after it has been created
2. AtomEconomy
Synthetic methods should be designed to maximize the incorporation of all materials
used in the process into the final product.
3. Less Hazardous Chemical Syntheses
Wherever practicable, synthetic methods should be designed to use and generate
substances that possess little or no toxicity to human health and the environment.
4. Designing Safer Chemicals
Chemical products should be designed to affect their desired function while
minimizing their toxicity.
5. Safer Solvents and Auxiliaries
The use of auxiliary substances (e.g., solvents, separation agents, etc.) should be made
unnecessary wherever possible and innocuous when used.
6. Design for Energy Efficiency
Energy requirements of chemical processes should be recognized for their
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environmental and economic impacts and should be minimized. If possible, synthetic
methods should be conducted at ambient temperature and pressure.
7. Use of Renewable Feedstocks
A raw material or feedstock should be renewable rather than depleting whenever
technically and economically practicable.
8. Reduce Derivatives
Unnecessary derivatization (use of blocking groups, protection/ deprotection,
temporary modification of physical/chemical processes) should be minimized or
avoided if possible, because such steps require additional reagents and can generate
waste.
9. Catalysis
Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.
10. Design for Degradation
Chemical products should be designed so that at the end of their function they break
down into innocuous degradation products and do not persist in the environment.
11. Real-time analysis for Pollution Prevention
Analytical methodologies need to be further developed to allow for real-time, inprocess
monitoring and control prior to the formation of hazardous substances.
12. Inherently Safer Chemistry for Accident Prevention
Substances and the form of a substance used in a chemical process should be chosen
to minimize the potential for chemical accidents, including releases, explosions, and
fires.
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In the light of above drawbacks there is necessity to develop an economical, ecofriendly and
commercially compatible process to recover benzoic acid.
The major advantages of the present invention are reducing waste, eliminating costly
remediation and saving energy. Moreover process is having fewer steps allowing faster
recovery of product, increasing plant capacity.
The major advantage of the present invention is reducing atom economy and Chemical
Oxygen Demand (COD) to help environment clean.
Summary of the invention:
The present invention relates to a process for recovery of benzoic acid (Formula-I).
0^0H
Formula-I
In one aspect, the present invention relates to recovey process for benzoic acid from benzoate
salt which comprises;
(a) Hydrolysing mother liquor of benzoylation reaction with inorganic mineral acid at
ambient temperature
(b) recovering benzoic acid with high purity
Detail description of the invention:
The present invention relates to an environmentally friendly and economical process for
recovery of benzoic acid (Formula-I).
Formula-I
In one embodiment, the present invention relates to recovery process for benzoic acid' from
benzoate salt which comprises;
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(a) Hydrolysing mother liquor of benzoylation reaction with inorganic mineral acid at
ambient temperature
(b) Stirring for 1 hr and washing filtered slurry with water and;
(c) recovering benzoic acid with high purity
The inorganic mineral acid used in step (a) is selected from the group consisting of
hydrochloric acid, hydrobromic acid, hydroiodic acid, sulphuric acid, nitric acid; phosphoric
acid. The reaction temperature for the above said process is 25-30°C.
The recovered benzoic acid is further used to prepare benzoic anhydride. Almost 70 %
benzoic anhydride prepared from recovered benzoic acid by using present invention method.
Hence 70 % atom economy reduces and results in cheaper, industrially feasible process.
Examples:
Example-1: Recovery of benzoic acid from benzyl chloride
To the 250 mL of aqueous layer of mother liquor of benzoylation reaction added concentrate
15 mL HC1 and stirred the reaction mixture at room temperature for 1 h. Filtered the slurry
and washed with 50 mL water, suck, dried for 15 - 30 min. The wet solid dried u/vacuum or
hot air oven at 70 - 75 °C for 5 -
1. A process for recovering of benzoic acid (Formula-I) comprising
0
"OH
Formula-I
(a) Hydrolysing mother liquor of benzoylation reaction with inorganic mineral acid at ambient temperature
(b) recovering benzoic acid

2. The process according to claim 1, wherein the inorganic mineral acid is selected from the group consisting of hydrochloric acid, hydrobromic acid, hydroiodic acid, sulphuric acid, nitric acid; phosphoric acid.
3. The process according to any of the preceding claims wherein the purity of benzoic acid is more than 99.96 %.