Nitrolim calcium cyanamide

 NITROLIM or CALCIUM CYANAMIDE

Nitrolim or calcium cyanamide is one of the most important fertilizers in the present day, contain about 20% of nitrogen. The formula of nitrolim or calcium cyanamide is CaNCN or CaCN₂ and it is represented as N≡C―N=Ca or [(Ca²⁺) (^-N=C=N^-)], it is a derivative of cyanamide, N≡C―NH₂. Nitrolim is grey powdered fertilizer.

When limestone means calcium oxide (CaO) and coke (C) heated in an electric furnace at about 2000⁰C, calcium carbide (CaC₂) is formed.

At 2000⁰C,   CaO + 3C ------> CaC₂ + CO

When this calcium carbide (CaC₂) treated with nitrogen (N₂), calcium cyanamide or nitrolim is formed, this reaction is highly exothermic.

CaC₂ + N₂ -------> CaNCN + C       ΔH = - 72.7 Kcal

Some important considerations during this manufacturing process are---

Temperature: Since the reaction is exothermic, so according to Le-chatelier principle, this reaction is highly favorable at low temperature, but this off set the activation energy of the reaction.

Activator: CaF₂ is used as an activator to overcome the above difficulty. At low temperature, CaF₂ activates the process of the reaction at a reasonably in speed.

Fixation: Nitrogen (N₂) fixation limit cannot pass over 85% limit.

Raw Materials

Raw materials required for the manufactured of nitrolim or calcium cyanamide are calcium carbide (CaC₂) [which is prepared from lime stone or calcium oxide (CaO) and coke (C)] and nitrogen (N₂).

Manufacturing Process

Powdered calcium carbide (CaC₂) along with CaF₂ (activator) are taken in the electric furnace fitted with pipe to get supply of nitrogen (N₂). In the electric furnace, the central carbon electrode is connected to high voltage mains. When the temperature of the electric furnace reaches to 900⁰C, highly exothermic reaction leading to the formation of the calcium cyanamide or nitrolim. Allowing the reaction to continue by its own liberated heat at about 40-60 hours for completion. During this process temperature is maintained at about 1000⁰C. After completion the reaction solid chank are taken out, and then disintegrated, powdered. Now first water is sprayed over the powdered to destroy any residual carbide and then spray oil. The grey powdered thus obtained is suitable for use.

Uses of Nitrolim or Calcium Cyanamide

Nitrolim or calcium cyanamide is used as a fertilizer due to its slow conversion into ammonia (NH₃) and nitrate (NO₃^-). So, it is a good fertilizer as its effects are prolonged nature.

Action of Calcium Cyanamide or Nitrolim as Fertilizer

In the soil, when finely powdered nitrolim is applied, it gets hydrolyzed to calcium hydroxide [Ca(OH)₂] and urea (H₂N―CO―NH₂). This hydrolysis process is catalysed by soil catalysis or microorganisms, which are present in the soil.

CaCN₂ + 4H₂O ------> Ca(OH)₂ + CO(NH₂)₂ + H₂O

Or, CaCN₂ + 3H₂O ------> Ca(OH)₂ + CO(NH₂)₂

The urea formed in this process, is then hydrolysed with the help of enzyme urease into ammonia. The ammonia is then converted to nitrates by oxidation with the help of enzyme of bacteria.

CO(NH₂)₂ + H₂O ------> CO + 2NH₃

2NH₃ + 3O₂ -----> 2NO₂^- . 2H₂O + 2H⁺ + Energy

2NO₂^- + O₂ -------> 2NO₃^- + Energy

Albendazole and Mebendazole

 Synthesis of Albendazole and Mebendazole

Albendazole

Albendazole is a benzimidazole derivative, widely used across the globe for the treatment of neurocysticerosis and echinococcosis and other intestinal nematode infection. Albendazole is found to be quite effective as a single dose treatment for ascariasis. Albendazole is also found in the treatment of infection caused by various worms such as roundworm, whipworm, threadworm and hookworm. A recommended multi dose therapy with albendazole is found to be very effective in the complete eradication of pinworm chlonorchiasis and capillariasis.

Synthesis of Albendazole

Albendazole is prepared by three steps----

Step – 1-----

In this step at first, 3-chloro-6-nitroacetanilide is reacted with propyl mercaptan, as a result 3-propylthio-6-nitroacetanilide is formed. The nitro group present at position 6 in 3-propylthio-6-nitroacetanilide is reduced by hydrogen in presence of palladium on carbon (Pd-C) as a catalyst. As a result, 4-(propylthio)-o-phenylenediamine is formed.

Step – 2-----

In this step, s-methylisothiourea sulfate is reacted with methylchloro formate in presence of NaOH at p^H 8. As a result, methyl-s-methylthiourea carboxylate is formed.

Step – 3------

In the final step, 4-(propylthio)-o-phenylenediamine formed in step–1 and methyl-s-methylthiourea carboxylate formed in step–2, are reacted. As a result, albendazole is formed.

Mebendazole

Mebendazole is also a benzimidazole derivative, widely used across the globe for the treatment of infection caused by hookworm, pinworm, roundworm, whipworm, guinea worm. Mebendazole is used for the treatment of infection caused by Trichuris trichiura, Enterobius vermicularis. Mebendazole is also used as an alternative medicine for Visceral Larva Migrans. Mebendazole is found very effective against nematodes and cestodes.

Synthesis of Mebendazole

Mebendazole is prepared by three steps---

Step – 1-----

In this step at first, 4-chlorobenzophenone reacted with mixed acid (HNO₃+H₂SO₄), as a result 4-chloro-3-nitrobenzophenone is formed. Now 4-chloro-3-nitrobenzophenone reacted with ammonia in presence of methanol at 125⁰C. As a result, 4-amino-3-nitrobenzophenone is produced. The nitro group present at position 3 in 4-amino-3-nitrobenzophenone is reduced by hydrogen in presence of palladium on carbon (Pd-C) as a catalyst. As a result, diaminobenzophenone is formed.

Step – 2-----

In this step, s-methylisothiourea sulfate reacted with methylchloro formate in presence of NaOH at p^H 8. As a result, methyl-s-methylthiourea carboxylate is produced.

Step – 3-----

In the final step, diaminobenzophenone formed in step-1 and methyl-s-methylthiourea carboxylate formed in step-2 are reacted. As a result, mebendazole is formed.