Nitration of methylbenzene 1). In organic chemistry, nitration is a general class of chemical processes for the introduction of a nitro group (−NO 2) into an organic compound. Toluene is predominantly used as an industrial feedstock and a solvent . As the solvent in some types of paint thinner , permanent markers , contact cement and certain types of glue, toluene is sometimes used as a recreational inhalant [ 16 ] and has the potential of causing severe neurological harm. Another example of a substitution reaction is the nitration of arenes; In these reactions, a nitro (-NO 2) group replaces a hydrogen atom on the arene; The benzene is reacted with a mixture of concentrated nitric acid The nitration of methyl benzoate is an example of electrophilic substitution. forming within the first hour after turning on the stir plate. Like. (i)€€€€€ Give the reagents used to produce the electrophile for this reaction. Ridd J. This means that the first step need to be the nitration and not the bromination. In the first step, the electrophile is generated. The carbocations formed from attack at ortho and para positions of toluene are more stable than the carbocation formed from meta position. Explain what this means with the help of simple diagrams using nitration as an example. Like any other hydrocarbons, benzene and methylbenzene burn in a plentiful supply of oxygen to give carbon dioxide and water. including the reduction of nitrobenzene and the oxidation of methylbenzene. 0. Chlorination of benzene to form chlorobenzene using chlorine in AlCl 3 catalyst . That means that you would use a lower The nitration of methylbenzene requires concentrated nitric acid (HNO₃) and sulfuric acid (H₂SO₄), usually at temperatures below 50°C. Friedel-Crafts alkylation. Also, as noted earlier, toluene undergoes nitration about 25 times faster than benzene, but chlorination of toluene is over 500 times faster than that of benzene. Nitration is an example of an electrophilic substitution reaction; The nitration of benzene requires a mixture of concentrated nitric acid (HNO 3) and sulfuric acid (H 2 SO 4) refluxed with benzene between 25 o C and 60 o C; Since phenol is more reactive, nitration can occur under milder conditions by reacting it with dilute nitric acid at room temperature shown below, can be prepared from methylbenzene by a sequence of nitration reactions. 3. freesciencelessons. 8. (iii) complete oxidation of the side-chain to give a benzoic acid. To produce benzenesulfonic acid from benzene, fuming sulfuric acid and sulfur trioxide are added. M. . 1. Concentrated HNO₃ and H₂SO₄ react to form The nitration of methylbenzene (toluene) Methylbenzene reacts rather faster than benzene - in nitration, the reaction is about 25 times faster. That means that you would use a lower temperature to prevent more than one nitro group being substituted - in this case, 30°C rather The nitration of methylbenzene (toluene) Methylbenzene reacts rather faster than benzene - in nitration, the reaction is about 25 times faster. That means that you would use a What is the mechanism for nitrating benzene? or methyl benzene? The nitrating mixture consists of concentrated nitric acid (source of the nitro group - NO2) and concentrated sulfuric acid which acts as a catalyst and as a strong acid. 2) A conversion from the nitro group to an amine. Nitration. Aromatic nitration. Another example of a substitution reaction is the nitration of arenes; In these reactions, a nitro (-NO 2) group replaces a hydrogen atom on the arene; The benzene is reacted with a mixture of concentrated nitric acid (HNO 3) and concentrated sulfuric acid (H 2 SO 4) at a temperature between 25 and 60 o C In this video we go through the 5 Must-Know Reactions of Benzene and 3 Must-Know Reactions of MethylBenzene. The experiment using methylbenzene took about six minutes to start making the products, but it took roughly five hours to completely use up the Nitration of methylbenzene Methyl benzene used to be called toluene. In this experiment, methyl benzoate is reacted with the nitronium ion to form methyl nitrobenzoate. Calculations described 1 Methylbenzene, C 6 H 5 CH 3 , is an aromatic hydrocarbon and is used widely as a solvent. The term also is applied incorrectly to the different process of forming nitrate esters (−ONO 2) between alcohols and nitric acid (as occurs in the synthesis of nitroglycerin). Nitration of benzene to form nitrobenzene using concentrated HNO 3 in concentrated H 2 SO 4 at 50 to 60 degree celsius . We'll explore specific examples of electrophilic substitution reactions, including nitration, chlorination, Friedel-Crafts acylation, and Friedel-Crafts alkylation. These halogen carriers include: 10. Aromatic rings can undergo nitration when treated with nitric acid HNO 3 in addition to the strong acid H 2 SO 4. The facts. Hydrogenation. That means that you would use a lower temperature to prevent more than one nitro group being substituted - Hint: As we know that nitration is a process where we can introduce a nitro group into an organic compound where nitrogen is attached with oxygen on one hand and carbon on the other hand. 0. Chlorination of Methylbenzene Chlorination of methylbenzene (also known as toluene) involves the substitution of a hydrogen atom in the methyl group by a chlorine atom. particularly benzene and methylbenzene. 1. See also Electrophilic substitution - nitration of benzene and If we use the nitration of benzene as a reference, we can assign the rate of reaction at one of the carbons to be 1. Outline the mechanism for the formation of 4-nitromethylbenzene from methylbenzene using NO 2 + as the electrophile. Find step-by-step Chemistry solutions and your answer to the following textbook question: Write the structure(s) of the major product(s) that you expect from each of the following electrophilic aromatic substitutions. Since there are six equivalent carbons in benzene, the total rate would be 6. Nitration . Alkylarenes are nitrated on the 2 or 4 position. Aromatic nitro compounds are important intermediates to anilines by Nitration of Benzene Questions. Step 1: Generation of electrophile nitronium ion NO HNO 3 + 2H 2 SO 4 → NO 2 + + H 3 O + + 2HSO 4 –. Fuming sulfuric acid, also refered to as oleum, is a concentrated solution of dissolved sulfur trioxide in sulfuric acid. Jones: Electrophilic Aromatic Substitution, Nitration, 14. With larger alkyl substituents the para position becomes favored. The difference between the resulting molecular structures of nitro The electrophilic substitution reaction between benzene and nitric acid. The Nitration of Methylbenzene (Toluene) Methylbenzene reacts rather faster than benzene – in nitration, the reaction is about 25 times faster. 1039/JR9650006845; Substituent effects of positive poles in aromatic substitution. The reaction below shows one common method of reducing the nitro group. Billions of kilograms of ethylbenzene and cumene are produced annually. 2. 12. 1965, 6845-6851 DOI: 10. Sulfonation of Benzene Nucleophilic Elimination Reactions. The kinetics of aromatic nitration depend on the nitrating method, which also bear directly or indirectly on the subject of nitration. The orientation of products in aromatic substitution (1,2-; 1,3-; and pathways and products are also explained for the reaction mechanisms of aromatic hydrocarbons like benzene and methylbenzene. The nitronium ion (NO 2 +) present in the mixture is the active species that attacks the organic compound to form an unstable complex. sulfuric acid & nitric acid with benzene/methylbenzene. (a) €€€€The mechanism of the nitration of methylbenzene is an electrophilic substitution. What type of reaction is nitration of toluene? You will find everything you need on the page about the nitration of benzene and methylbenzene. C. Alternative mechanisms have been proposed, as the one involving single electron transfer (SET). . (a)4-Nitromethylbenzene can be formed by the nitration of methylbenzene. The carbonyl group withdraws electron density from the ring deactivating it towards electrophilic substitution. Although all three intermediates are resonance-stabilized, the ortho and para intermediates are more Question: 5. Friedel-Crafts acylation. As such, its systematic IUPAC name is methylbenzene. a) The methyl group in methylbenzene is 2,4-directing. Outline the mechanism for the formation of 4-nitromethylbenzene from methylbenzene using NO 2 + as the Nitration. This leads to the formation of the nitronium ion NO 2 + which is the active electrophile. Nitration is an electrophilic aromatic substitution reaction where a nitro group (NO2) is introduced into an aromatic compound. One of the most famous is 2-methyl-1,3,5-trinitrobenzene, originally called trinitrotoluene or TNT. That means that you would use a lower temperature to prevent more than one nitro group being Friedel-Crafts acylation of methylbenzene (toluene) The reaction is just the same with methylbenzene except that you have to worry about where the acyl group attaches to the ring relative to the methyl group. The nitration reactivity order is: methylbenzene > benzene > nitrobenzene. Once the electrophile has been generated, it will carry out an electrophilic attack on the benzene ring. Explain briefly why. In the nitration of methylbenzene, a nitro group replaces a hydrogen atom on the benzene ring. There is good evidence that the synthesis of phenol from chlorobenzene does not proceed by the addition-elimination mechanism (S N Ar) as previously described. The electrophile NO 2 + ion is generated by reacting concentrated nitric acid (HNO 3) and concentrated sulfuric acid (H 2 SO 4). 10 • Synthesis of Polysubstituted Benzenes As discussed in the Introduction to Organic Synthesis in Section 9. Again, due to the electron-donating alkyl groups in alkylarenes, nitration of methylbenzene will occur on the 2 and 4 position; Nitration of alkylarenes. b) Write the equation for the formation of the electrophile from the nitrating mixture of concentrated nitric and sulphuric acids. Phenol (C 6 H 5 OH) and phenylamine (C 6 H 5 NH 2) are also activated in the 2 and 4 positions Aromatic rings undergo nitration and sulfonation through the electrophilic aromatic substitution mechanism. Examples of aromatic nitration substitution reactions (i) + HNO 3 ==> + H 2 O. be prepared from methylbenzene by a sequence of nitration reactions. Methylbenzene is more reactive towards electrophiles than benzene itself. Benzene is mainly used in the manufacture of other more complex chemicals, such as ethylbenzene and cumene. Many aromatic nitro compounds are used as explosives. 23 days ago. This can be nitrated in the 2,4,6 position: 2) Halogenation of benzene Benzene will not react with bromine on its own. In what way does changing the We find, for example, that nitration of nitrobenzene occurs smoothly at 95 ºC, giving meta-dinitrobenzene, whereas bromination of nitrobenzene (ferric catalyst) requires a temperature of 140 ºC. Write an equation or equations to show the formation of this electrophile. Nitration of Methyl Benzoate . 1) A nitration. The nitrated hydrocarbon is formed when a proton is removed from the complex [1-4]. Concentrated HNO₃ and H₂SO₄ react to form the nitronium ion (NO₂⁺), the active electrophile in the reaction. The nitration of toluene forms nitro toluene. 9, pp 704-717. There Reacting methylbenzene with a mixture of concentrated nitric and sulphuric acids gives both 2-nitromethylbenzene and 4-nitromethylbenzene. In this context, the methyl group (CH₃) is an electron-donating group. The methyl group has a small, but not insignificant effect of raising the electron density around the ring, particularly at the ring carbons 2 (= 6) and 4 (the 'fuzzy' Arene reactivity, especially during nitration, depends significantly on the structure of the arene itself. 3 During both of our experiments today that is what we did. What is benzene? Before we go any further, let’s first remind ourselves about benzene. Nitration of Mechanism. Continue reading. In "aromatic nitration," aromatic organic compounds are nitrated via an electrophilic aromatic substitution mechanism involving the attack of the electron-rich benzene ring by the nitronium ion. While the nitro group could replace any of the hydrogens on the ring, giving drop zone potential isomers, not all of them are equally likely. and methylbenzene: Nitration is important synthetically because it is one of the best ways to add an amino group to a benzene ring. Organic synthesis of nitro aromatic compounds by reaction of conc. That means that you would use a lower temperature to prevent more than one nitro group being substituted - 7. ; Aromatic rings can undergo sulfonylation when treated with The overall reaction of nitration of arenes. The electrophilic substitution reaction between benzene and nitric acid. Mechanism: This involves the following steps. You just have to be careful about the way that you draw the structure of the intermediate ion. This can be done by reducing the nitro group into an amino group through the process of hydrogenation. 1(c) and 30. However the 3-position is less deactivated towards Reacting methylbenzene with a mixture of concentrated nitric and sulfuric acids gives both 2-nitromethylbenzene and 4-nitromethylbenzene. (a) The nitration of methylbenzene (toluene) happens about 25 times faster than the nitration of benzene. Due to the directing effect of the methyl group, the main products will be 1-methyl- drop zone-nitrobenzene and 1-methyl- drop zone-nitrobenzene. 9, one of the surest ways to learn organic chemistry is to work synthesis problems. Step 2: The nitronium ion acts as an electrophile in the process which further reacts with benzene to form an arenium ion. It is readily nitrated and it can form mono-, di-, or tri-nitromethylbenzenes. Anderson. You can also ignore the final green box on the page. Because the end product is meta a meta directing group must be utilized. The nitration of an aromatic ring is an important synthetic pathway to generating arylamines. This page gives you the facts and a simple, uncluttered mechanism for the free radical substitution reaction between methylbenzene (previously known as toluene) and chlorine. Step 1: The alkene reacts with the HCl in the same way as in electrophilic addition : reactions: C Mechanism. The ability of compounds such as nitronium tetrafluoroborate to bring about the nitration of aromatic compounds is good evidence in support of the proposed mechanism. Arenes are aromatic hydrocarbons (most commonly based on benzene rings) such as benzene and methylbenzene. If you want the mechanism explained to you in detail, there is a link at the bottom of the page. If we examine the nitration of toluene, tert-butylbenzene, chlorobenzene and ethyl benzoate in the same manner, we can assign relative rates to the ortho, meta and para sites in each of these Nitration. Halogenation . For example: For benzene:. Once again, ignore any links to the mechanisms for these reactions for now. Manufacture . Steven W. 1 Methylbenzene, C 6H 5CH 3, is an aromatic hydrocarbon and is used widely as a solvent. That is energetically easier because it doesn't involve breaking the delocalised electron system. Alkylarenes such as methylbenzene undergo halogenation on the 2 or 4 positions. In some cases it may be necessary to have an activating group to facilitate substitution, which otherwise would be very difficult. The methyl group of methylbenzene directs nitration preferentially to the 4 position, and subsequent oxidation with chromic acid yields 4-nitrobenzoic acid: Figure 24-5: Synthetic routes to 1,4-dinitrobenzene. co. The mechanism for nitration of benzene: Step 1: Nitric acid accepts a proton from sulphuric acid and then dissociates to form nitronium ion. (a) 4-Nitromethylbenzene can be formed by the nitration of methylbenzene. 7. Draw their structures and give their names. Step 3: The arenium ion then loses its proton to Lewis base forming nitrobenzene. If you want the nitration mechanism explained to you in detail, there is a link at the bottom of the page. Statement 30. Following nitration, TNT is stabilized using a procedure known as sulfation, in which the crude TNT is treated with an aqueous sodium, sulfite solution to get rid of any less stable isomers of TNT and other undesirable reactions by-products. Of the nitro, bromine, and amine group, only the nitro group is meta direction. Whether you would get addition to the ring if you used a large excess of chlorine and did the reaction for a long time, I don't know. Discussion Nitration is the process of adding a nitro group (NO 2 ) to a benzene ring. The ability to plan a successful multistep synthesis of a complex molecule requires a working knowledge of the uses and limitations of a great many organic reactions. (a) The mechanism of the nitration of methylbenzene is an electrophilic substitution. Normally, the methyl group in methylbenzene directs new groups into the 2- and 4- positions (assuming the methyl group is in the 1 be prepared from methylbenzene by a sequence of nitration reactions. Soc. Like benzene, chlorobenzene The nitration of methylbenzene might be considered an oddball compared to nitration of other monoalkylated benzene rings. 5. For example, the para product is favored (around 55%) for the nitration of ethylbenzene. benzene + nitric acid ==> nitrobenzene + water- Conclusion: In conclusion, the nitration of methylbenzene results in 1-methyl-2-nitrobenzene and 1-methyl-4-nitro-benzene making it ortho/para and a deactivator thanks to the nitro group. explain the Chlorination and nitration of methylbenzene. Draw the most likely product from the reaction between methylbenzene and limited amount of nitric acid in the presence of sulfuric acid, and at a low temperature. Arenes like benzene, methylbenzene, and ethylbenzene vary in reactivity when undergoing nitration reactions due to substituent effects. Friedel-Crafts reactions. The manufacture of arenes from petroleum by reforming. H. (a) Nitration of methylbenzene (toluene); (b) sulfonation of methylbenzene (toluene); (c) nitration of 1,1-dimethylethylbenzene (tert-butylbenzene); (d) sulfonation of 1,1 Toluene | C6H5CH3 or C7H8 | CID 1140 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological activities, safety Using the exact same experimental conditions we can then measure the rate of the reaction when toluene (methylbenzene, The nitration of the anilinium ion in 90—100% sulphuric acid Madeline Brickman and J. If I keep on with the reaction after a few hours I will Nitration to give nitro-aromatics like nitrobenzene. 4e, pp 686-687. It requires the help of a type of catalyst called a halogen carrier. Chem. Friedel-Crafts reactions are also electrophilic substitution reactions; Remember that benzene, methylbenzene and similar hydrocarbons based on benzene rings are collectively known as arenes. uk/a-level-revision-videos/a-level-chemistry/In this video, w Benzene and three of its chemical derivatives, chlorobenzene, methylbenzene and phenol, are aromatic compounds which have a variety of industrial applications. Combustion. This compound, shown below, can be prepared from methylbenzene by a Nitration. Normally, the methyl group in methylbenzene directs new groups into the 2- and 4- positions (assuming the methyl group is in the 1 methylbenzene: (i) substitution reactions with chlorine and with bromine. The nitrating mixture of HNO 3 and H 2 SO 4 is The nitration of methylbenzene. This is facilitated by the electrophile, the nitronium ion (NO_2^+), formed from the reaction of In this video we go through the 5 Must-Know Reactions of Benzene and 3 Must-Know Reactions of MethylBenzene. A slight majority but the percent para increases with larger alkyl Problem 4-10 Why is nitration with ethanoyl nitrate accelerated by added fluoroboric acid, \ but retarded by added hydrochloric acid? Problem 4-11 Why do fairly reactive arenes, such as benzene, methylbenzene, and ethylbenzene, react with excess nitric acid in nitromethane solution at a rate that is independent of the concentration of the Benzene Nitration Peyton Posey April 7 th, 2020 Virtual Chemistry Lab Organic Chemistry 1 Lab Section 1: Abstract In this experiment I monitored and observed the nitration of methylbenzene and benzaldehyde separately. Our first experiment started with methylbenzene as the reagent and a mixture of nitric acid/sulfuric Step 1: Understanding Nitration. Answer Created with AI. Write an The diagram below shows the 2, 4 and 6 activated sites on the methylbenzene molecule. (ii) nitration. About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright Nitration of toluene might occur either ortho, meta, or para to the methyl group, giving the three carbocation intermediates shown in in Figure \(\PageIndex{3}\). Benzene is treated with a mixture of concentrated nitric acid and concentrated sulfuric acid at a temperature not exceeding 50°C. This question is about substitution in methylbenzene and nitrobenzene. Notes to the Instructor: This experiment is suitable for an advanced project in the full year organic laboratory or as a project in an upper level organic course. Questions; Answers; Methylbenzene undergoes a similar reaction to the one above. Another example of a substitution reaction is the nitration of arenes; In these reactions, a nitro (-NO 2) group replaces a hydrogen atom on the arene; The benzene is reacted with a mixture of concentrated nitric acid (HNO 3) and concentrated sulfuric acid (H 2 SO 4) at a temperature between 25 and 60 o C Let us understand this on the basis of potential energy diagram for nitration of methylbenzene (Fig. The sulfur in sulfur trioxide is electrophilic because the oxygens pull electrons away from it because oxygen is very electronegative. For example, aromatic nitration displays second-order kinetics in sulphuric acid (when used in nitrating mixture), and first-order kinetics in We'll explore specific examples of electrophilic substitution reactions, including nitration, chlorination, Friedel-Crafts acylation, and Friedel-Crafts alkylation. FAQs. Aromatic nitro compounds are generally prepared by direct nitration of arenes with nitrate mixture. Nitration is an introduction of nitrogen dioxide into a chemical compound acid . This is facilitated by the electrophile, the nitronium ion (NO_2^+), formed from the reaction of concentrated nitric and sulphuric acid. 1(d) (a) Nitration of methylbenzene (toluene); (b) sulfonation of methylbenzene (toluene); (c) nitration of 1,1 -dimethylethylbenzene (tert-butylbenzene); (d) sulfonation of 1,1 -dimethylethylbenzene (tert-butylbenzene). An introduction to the arenes and their physical properties. The mechanism is exactly the same as the nitration of benzene. shown below, can be prepared from methylbenzene by a sequence of nitration reactions. In the process the methyl benzoate was nitrated to form a methyl m-nitro benzoate . The nitration of methylbenzene (toluene) Methylbenzene reacts rather faster than benzene - in nitration, the reaction is about 25 times faster. That means that you would use a lower temperature to prevent more than one nitro group being substituted - Nitration benzene reacts with a mixture of concentrated nitric acid and concentrated sulphuric acid at 50°C to form nitrobenzene. (iv) hydrogenation of the benzene ring to form a cyclohexane ring (b) (i) describe the mechanism of electrophilic substitution in arenes, as exemplified by the Product Distribution in the Nitration of Toluene. 3) A bromination. Nitration to give nitro-aromatics like nitrobenzene. Nitration of benzene to form nitrobenzene using concentrated HNO3 in concentrated H2SO4 at 50 to 60 degree celsius. The electrophile in nitration is the nitronium ion which is generated from nitric acid by protonation and loss of water , using sulphuric acid as the dehydrating agent. 1 The reagents, reaction conditions and equations for the nitration of aromatic compounds. (b) When you substitute a single nitro group into methylbenzene, you get a mixture of two products. This procedure has been adapted from the microscale procedure described in the third edition of With methylbenzene under those conditions, you get substitution in the methyl group. Due to a highly activating effect of the hydroxyl group in phenols, they Nitration is one of the most important examples of electrophilic substituition. Step 2: The electrophile NO 2 + attacks the benzene ring to form a carbocation Methylbenzene can undergo nitration, sulphonation, and halogenation through the aid of a halogen carrier. o. The nitration of benzene and methylbenzene. Overall completion of the reaction though took four hours to occur. Disubstituted Benzenes: ortho, meta, and para Substitution, 14. Since most of the examples listed above are benzene derivatives, we shall discuss the mechanism of benzene nitration. This. Background . The nitration of methylbenzene, also known as toluene, involves introducing a nitro group (NO₂) to the benzene ring via an electrophilic aromatic substitution (EAS). If you substitute a nitro group, -NO 2, into the benzene ring in methylbenzene, you could possibly get any of the following products: The carbon with the methyl group attached is thought of as the number 1 carbon, The nitration of methylbenzene requires concentrated nitric acid (HNO₃) and sulfuric acid (H₂SO₄), usually at temperatures below 50°C. Friedel-Crafts acylation of methylbenzene (toluene) The reaction is just the same with methylbenzene except that you have to worry about where the acyl group attaches to the ring relative to the methyl group. For example, treatment of para-chlorotoluene with sodium hydroxide solution at temperatures above 350 ºC gave an equimolar mixture of meta- and para-cresols 7. Alkylbenzenes other than methylbenzene can be formed by reacting benzene with alkenes in the presence of HCl and AlCl: 3, under reflux at temperatures below 50. The mechanism is exactly the same as the How to write the mechanism for the nitration of methylbenzene. Halogenation of Phenols. (i) Give the reagents used to produce the electrophile for this reaction. 2 The electrophilic substitution of an arene - nitration mechanism. The nitration of methylbenzene (toluene) Methylbenzene reacts rather faster than benzene - in nitration, the reaction is about 25 times faster. Must-Know Benzene Reaction. That is energetically easier because it doesn't involve breaking the delocalized electron system. In the case of methylbenzene (toluene), the reaction typically involves the use of concentrated nitric acid (HNO3) and concentrated sulfuric acid (H2SO4) as a nitrating mixture. Complete answer:As we know that nitration is a process where we can introduce a nitro group When phenol is treated with concentrated nitric acid, the nitration results in the formation of 2, 4, 6-trinitrophenol (commonly called picric acid). Methylbenzene has a methyl group attached to a benzene ring. Reacting methylbenzene with a mixture of concentrated nitric and sulphuric acids gives both 2-nitromethylbenzene and 4 In the nitration of methylbenzene, a nitro group replaces a hydrogen atom on the benzene ring. The reaction is shown below : HNO3 + 2H2SO4 NO2+ + H3O+ + 2HSO4- In this experiment we will put 16. Benzene is treated with a mixture of concentrated nitric acid and concentrated sulphuric acid at a temperature not exceeding 50°C. However, all You can find all my A Level Chemistry videos fully indexed at https://www. With methylbenzene under those conditions, you get substitution in the methyl group. This is due to the electron-donating alkyl groups which activate these positions. The reagents were added very slow to avoid a vigrous reactions and the temperature was maintained low to avoid formation of dinitro product . qkavj jdtvd yjsnqmf hepbus wgjjc igulx sdul oqzdu dxf qstnb