Unit process

Brief presentation on Unit processes of chemical engineering.

1. Unit Process es of Chemi cal engineering

2. Chemical process is combination of unit processes and Unit operation. A process may require many unit operations to obtain the desired product from the starting materials, or feedstocks. Unit process involves Principle chemical conversions leading to synthesis of various useful product and provide basic information regarding the reaction temperature and pressure, extent of chemical conversions and yield of product of reaction nature of reaction whether endothermic or exothermic, type of catalyst used. Unit operations involve the physical separation of the products obtained during various unit processes. Various unit processes in chemical industries are given in following Table INTRODUCTION

3. SULPHONATION Overall transformation: Ar/R-H to Ar/R-SO3H Reagents: Conc. H2SO4, chlorosulfonic acid, metallic sulfates,etc. Electrophilic species: SO3 which can be formed by the loss of water from the sulphuric acid. It is exothermic, but not highly corrosive. Unlike the other electrophilic aromatic substitution reactions, sulphonation is reversible. Reaction mechanism Typical conditions involve heating the aromatic compound with sulfuric acid. Sulfur trioxide or its protonated derivative is the actual electrophile in this electrophilic aromatic substitution. To drive the equilibrium, dehydrating agents such as  thionylchloride  can be added. Applications : In production of linear alkyl benzene sulphonates, toluene sulphonates, saccharin,etc.

4. REACTION MECHANISM

5. HALOGENATION Overall transformation: Ar/R-H to Ar/R-X Reagents : Chlorine, hypochloite ,hydrobromic acid,etc. It is carried out in the presence of a catalyst which acts as a halogen carrier. The main function of halogen carrier is to polarise the halgen-halogen bond and generate the electrophile. Halogenation of aromatic compounds differs from the halogenation of alkenes ,which do not require a lewis acid catalyst. Halogenation by reaction type:- 1)Free radical halogenation 2)Addition of halogens to alkenes and alkynes 3) Halogenation of aromatic compounds Applications : In formation of halogen derivatives such as CCl4, CFCs, Alkyl halides,etc.

6. REACTION MECHANISM

7. NITRATION Overall transformation: Ar/R-H to Ar/R-NO 2. Reagents: Fuming Conc. HNO 3 , mixture of HNO 3 & H 2 SO 4. It involves introduction of nitro group into a compound. Aromatic compounds are nitrated via EAS mechanism. The formation of a nitronium ion from HNO 3 & H 2 SO 4 and subsequent reaction of the ion with the sample takes place. Nitration reactions are notably used for the production of explosives, for example the conversion of guanidine to nitroguanidine and the conversion of toluene to trinitrotoluene. Applications: The nitrated derivatives have applications in industry as solvents, explosives, TNT, Nitro benzene, etc.

8. REACTION MECHANISM Step 1: Nitric acid accepts a proton from sulphuric acid and then dissociates to form nitronium ion. Step 2: The nitronium ion acts as an electrophile in the process which further reacts with benzene to form arenium ion.

9. Step 3: The arenium ion then loses its proton to Lewis base forming nitrobenzene. Examples :-

10. ESTERIFICATION When alcohols or phenols reacts with carboxylic acid in presence of acidic media formation of ester take place this process is know as Esterification reaction . Reversible reaction. Known as (ficher-speier Esterification ). Uses of Esterification reaction 1.Polymer industry Terylene,PMMA and cellulose ester. 2.Food industry Synthetic oils,soap and artificial sweetening agent. 3.Pharmaceutical industry Aspirin- in treatment of fever,as pain killer,to prevent heart attacks.

11. EXAMPLES OF ESTERIFICATION REACTION

12. MECHANISM OF REACTION

13. HYDROGENATION When unsaturated organic compound reacts with Hydrogen gas in presence of a catalyst such as Ni,Pd,or Pt.formation of less unsaturated organic compound take place .these types of reaction is called Hydrogenation. Industrial application of Hydrogenation reaction Food industry Processing of vegetable oils. Petro chemical industry To convert alkenes and aromatics into saturated alkanes and cycloalkanes. Organic chemistry

14. EXAMPLES OF HYDROGENATION REACTION

15. MECHANISM OF REACTION AND EXAMPLE

16. OXIDATION In reference to organic molecules, carbon atom gain bond to more electro negative elements, most commonly oxygen. some important oxidising agents. KMnO4,K2Cr2O7, conc.H2So4,O2,O3, H2O2,Mno2, Oso4,pcc,m-cpba etc. Important products of oxidation reaction and their application ketone Acetone-nail paint remover and for acne treatment. Organic solvent. 2. Aldehyde Formaldehyde + 37% H2O=formalin. Germicide, fungicide and insecticide for plant and vegetables. For bakelite,u.f resin and melamine. Solvent Perfumes and flavouring agent.

17. 3.Vanillin Flavouring agent of vanilla beans . 4.Benzoic acid It’s salts are used as food preservatives. 5.Acetic acid Solvent Food preservative. 3-9% acetic acid by volume is vinegar.

18. TABLE OF IMPORTANT OXIDATION REACTIONS

19. Hydrolysis is a chemical reaction that occurs between water and another compound. During the reaction, chemical bonds are broken in both molecules, causing them to break apart. The water molecule splits to form positively Charged  hydrogen (H + ) and negatively charged hydroxide (OH - ) ions, and the other molecule splits into two simpler sections, also with positive and negative charges. H +  and OH -  ions attach to each of these sections. HYDROLYSIS

20. Hydrolysis is used both in inorganic and organic chemical industry. Typical application is in oil and fats industry during soap manufacture where hydrolysis of fats are carried out to obtain fatty acid and glycerol followed by addition of sodium hydroxide to form soap. Other application is in the manufacture of amyl alcohols. Some of the major product using hydrogen is methanol, propane, butane, production of alcohol.

21. Various types of hydrolysis reaction may be pure hydrolysis, hydrolysis with aqueous acid or alkali, dilute or concentrated, alkali fusion, hydrolysis with enzyme and catalyst. Preparation of ethanol from ethylene: CH 2 = CH 2 (g) + H 2 O (g) catalyst CH 3 CH 2 OH (g) + H H = - 45 kJ mol -1

22. Polymerization is a chemical process by which polymer molecule is formed the same or different types of monomers. Polymerization maybe carried out either with single monomer or with co monomer. Polymerization reaction can be addition or condensation reaction. Various polymerization methods may be bulk, emulsion, solution, suspension. Application : Manufacture of polymer, synthetic fiber, synthetic rubber, polyurethane, paint and petroleum industry for high octane gasoline. POLYMERIZATION

23. Typical important products from polymerization are : Polyethylene , PVC, poly styrene, nylon, polyester, poly butadiene, poly styrene, phenyl, urea, melamine and alkyd resins epoxy resin, silicon polymers, poly vinyl alcohol etc. Example of polymerization reaction :

24. Case Study

25. “WHAT IS BHOPAL GAS TRAGEDY ?” The  Bhopal gas tragedy  (commonly referred to as  Bhopal disaster ) was a gas leak incident in India, considered one of the world's worst industrial catastrophes. It occurred on the night of 2nd–3rd December 1984 at the Union Carbide India Limited (UCIL) pesticide plant in Bhopal, Madhya Pradesh. A leak of  methyl isocyanate (MIC) gas and other chemicals from the plant resulted in the exposure of hundreds of thousands of people.

26. THE ACCIDENT During the night of 2–3 December 1984, water entered Tank E610 containing 42 tons of MIC. The resulting exothermic reaction increased the temperature inside the tank to over  200°C (392 °F) and raised the pressure. About 30 metric tons of methyl isocyanate (MIC) escaped from the tank into the atmosphere of Bhopal in 45 to 60 minutes.

27. FACTORS LEADING TO THE GAS LEAK Storing MIC in large tanks and filling beyond recommended levels, Poor maintenance, Failure of several safety systems, Safety systems being switched off to save money—including the MIC tank refrigeration system which could have mitigated the disaster severity, Plant location close to a densely populated area, Undersized safety devices, The dependence on manual operations,

28. THE DEVASTATION The official immediate death toll was 2,259 and the government of Madhya Pradesh has confirmed a total of 3,787 deaths related to the gas release. Others estimate 8,000 died within two weeks and another 8,000 or more have since died from gas-related diseases. A government affidavit in 2006 stated the leak caused 5,58,125 injuries including 38,478 temporary partial and approximately 3,900 severely and permanently disabling injuries. 2,000 bloated animal carcasses had to be disposed.

29. HEALTH EFFECTS Short term health effects Apart from MIC, the dense gas cloud may have contained  phosgene,  hydrogen cyanide,  carbon monoxide,  hydrogen chloride,  oxides of nitrogen,  monomethyl amine (MMA) and  carbon dioxide, either produced in the storage tank or in the atmosphere. The initial effects of exposure were coughing, vomiting, severe eye irritation and a feeling of suffocation. The acute symptoms were burning in the respiratory tract and eyes, blepharospasm, breathlessness, stomach pains and vomiting .

30. Bibliography http://www.hindustantimes.com/india/bhopal-gas-tragedy-burning-of-toxic-waste-begins-secretly/story-6iqgPOBcpuQvF0aErdwYYJ.html http://timesofindia.indiatimes.com/city/bhopal/Sabotage-led-to-Bhopal-gas-tragedy-Former-plant-manager-of-UCIL/articleshow/53303945.cms http://www.dnaindia.com/analysis/column-bhopal-gas-tragedy-will-the-suffering-ever-end-2040370 http://byjus.com/chemistry/benzene-reactions/ http://nptel.ac.in/courses/103107082/module1/lecture3/lecture3.pdf https://en.wikipedia.org/wiki/Unit_operation BOOKS:- Organic Chemistry by Dr.O.P Tandon & R.T Morrison , Unit Processes in Organic Synthesis. By P. H. Groggins .

31. Thank you A Presentation By:- Makineedi Venkat, Raj Patel &Yash Soni. SCHOOL OF TECHNOLOGY GSFC UNIVERSITY VADODARA, GUJARAT