Carbohydrazide is the chemical compound with the formula OC(N2H3)2.
It is a white, water-soluble solid.
It decomposes upon melting.
A number of carbazides are known where one or more N-H groups are replaced by other substituents.
They occur widely in the drugs, herbicides, plant growth regulators, and dyestuffs.
IUPAC name: 1,3-Diaminourea
CAS Number: 497-18-7
Chemical formula: CH6N4O
Molar mass: 90.09 g/mol
Density: 1.341 g/cm3
Melting point: 153 to 154 °C
Carbohydrazide is white crystal powder.
Carbohydrazide is very soluble in water and soluble in alcohol.
Carbohydrazide decomposes on heating or exposure to uv to form ammonia, hydrogen, and nitrogen, which may be explosive with a blue flame when catalyzed by metal oxides and some metals such as platinum or raney nickel
Carbohydrazide has dibasic and very reactive properties.
Carbohydrazide is used as a component in jet fuels because it produce a large amount of heat when burned.
Carbohydrazide is used as rocket fuel. Carbohydrazide is used as an oxygen scavenger for water boiler feed and heating systems to prevent corrosion damage.
Carbohydrazide is used as a reducing agent for the recovery of precious metals.
Carbohydrazide is used as a polymerization catalyst and a chain extender in urethane coatings.
Carbohydrazide is used as an auxiliary in photographic industry to prevent discolouration.
Carbohydrazide is used as an intermediate for pharmaceuticals, stabilizers and water treatment chemicals.
Carbohydrazide and its derivatives are versatile intermediates.
They have active applications in organic synthesis for agrochemicals, pharmaceuticals, photographic, heat stabilizers, polymerization catalysts, flame- retardants, blowing agents for plastics, explosives, and dyes.
Carbohydrazide Chemical Properties, Uses, Production
Carbohydrazide is a white crystalline thin and short columnar crystal or white powder at room temperature.
Carbohydrazide is insoluble in alcohol, easily soluble in water with dissolution absorbing heat.
Carbohydrazide is insoluble in alcohol, ether, and benzene.
Owing to that, it is a kind of derivative of hydrazine and thus having strong reduction ability. It is non-toxic, and can replace hydrazine and oximes.
Carbohydrazide has a broad range of application in industry.
For example, it can be used as the oxygen scavenging agent of boiler water in the field of water treatment and is regarded as most advanced materials for oxygen scavenging of boiler water.
Carbohydrazide has a low toxicity and high melting point with its deoxidizing efficiency being far greater than the current materials used and is a idea product for both safety and environmental protection;
Carbohydrazide can also be used as a rocket propellant components; moreover, owing to that its hydrogen atoms attached to the nitrogen atom is easily substituted by other groups, it can be used as the cross-linking agents of elastic fibers in the textile field, the formaldehyde scavenger, as well as the antioxidant of carotene pigment.
In addition, adding an appropriate amount of carbohydrazide to the phenol fungicides containing can play a role on preventing discoloration and rancidity.
As a chemical raw material and chemical industry intermediates, it is widely used in medicine, herbicides, plant growth regulators, dyes and other industries.
Oxygen scavenger of the boiler water
When acting as the oxygen scavenger of boiler water, carbohydrazide may be directly added into the water while its aqueous solution can also be used.
The usage amount of carbohydrazide for scavenging 1mol O2 is 0.5mol, and should be appropriately in excess.
The proper temperature range is 87.8-176.7 ℃.
The optimal time for applying carbohydrazide is after the thermal scavenging of oxygen.
The reaction of oxygen and carbohydrazide is as follows: CON4H6 + 2O2 = 2N2 + 3H2O + CO2
Reference quality standards
Appearance: fine white crystals or white short columnar crystals
Free hydrazine ≤250.0mg/L
Loss of weight by drying ≤0.2%
PH (12% aqueous solution) 8.45 ± 1.25
Carbohydrazide is widely used in the production of pharmaceuticals, herbicides, plant growth regulators, dyes, etc.
(1) carbohydrazide is a derivative of hydrazine with a strong reduction.
Carbohydrazide can be not only used as the intermediates for producing energy-containing materials, but also can be used directly as the components of explosives and propellants.
(2) it can be used as the preservative of refinery equipment and can also be used as the oxygen scavenger of boiler water treatment agent
(3) It can be used as the cross-linking agent of the elastic fiber in the field of chemical fiber industry
(4) it can be used as the chemical raw materials and chemical industrial intermediates and is widely used in medicine, herbicides, plant growth regulators, dyes and other industries.
Carbohydrazide can be used as the component of the rocket propellant, the stabilizer of color development and soap quality, the antioxidants of rubber, the oxygen scavenger of boiler water, and the passivation agent of metal.
Carbohydrazide is a derivative of hydrazine with a strong reduction.
Carbohydrazide can be used as the intermediate of producing energy-containing materials and also be used directly for the components of explosives and rocket propellant.
Carbohydrazide can also be used as the oxygen scavenger of boiler water and is the most advanced materials for scavenging oxygen of boiler water in the world today.
Carbohydrazide has low toxicity, high melting point and a deoxidation efficiency being far greater than the materials currently used.
Carbohydrazide is an ideal product for both safety and environmental protection.
In addition, it can be used as the cross-linking agent of the elastic fiber in the field of chemical fiber industry.
Carbohydrazide can also be used as the chemical raw materials and chemical industrial intermediates and is widely used in medicine, herbicides, plant growth regulators, dyes and other industries.
Intraperitoneal-mouse LD50: 167 mg/kg; Intravenous-Mouse LD50: 120 mg/kg.
Explosive and hazardous characteristics
it is explosive upon heating; it can generate explosive diazide compound upon reaction with nitrous acid.
Flammability and hazard characteristics
thermal decomposition into toxic nitric oxide gas.
Water, carbon dioxide, dry powder, foam.
Organic intermediate and photographic chemical.
ChEBI: A carbohydrazide obtained by formal condensation between hydrazinecarboxylic acid and hydrazine.
Poison by intravenous and intraperitoneal routes. Reacts with nitrous acid to form the explosive carbonic dazide. When heated to decomposition it emits toxic fumes of NOx.
Carbohydrazide is a white crystalline powder or pellets. The active content of carbohydrazide is 98.0 % - 100.9%.
Carbohydrazide can be used as an oxygen scavenger to prevent corrosion especially in a boiler feed system, rocket propellant components, color images and the quality of soap stabilizers, antioxidants rubber, boiler water deoxidants, and metal passivation agents.
It is also used as an intermediate for organic synthesis.
CAS No.: 497-18-7
Molecular Formula: CH6N4O
Molecular Weight: 90.09
hydrazide hydrazinecarboxylic acid
Carbohydrazide can be used:
• As an oxygen scavenger.
• In the synthesis of polydentate Schiff base ligands with various aldehydes and ligands by condensation.
• In the synthesis of trifluoromethyl-containing (E)-N′-arylidene-1H-pyrazole-1-carbohydrazides by cyclocondensation reaction which shows antioxidant and antimicrobial properties.
Industrially the compound is produced by treatment of urea with hydrazine:
OC(NH2)2 + 2 N2H4 → OC(N2H3)2 + 2 NH3
It can also be prepared by reactions of other C1-precursors with hydrazine, such as carbonate esters.
It can be prepared from phosgene, but this route cogenerates the hydrazinium salt [N2H5]Cl and results in some diformylation.
Carbazic acid is also a suitable precursor:
N2NH3CO2H + N2H4 → OC(N2H3)2 + H2O
The molecule is nonplanar.
All nitrogen centers are at least somewhat pyramidal, indicative of weaker C-N pi-bonding.
The C-N and C-O distances are about 1.36 and 1.25 Å, respectively.
Oxygen scrubber: carbohydrazide is used to remove oxygen in boiler systems.
Oxygen scrubbers prevent corrosion.
Precursor to polymers: carbohydrazide can be used as a curing agent for epoxide-type resins.
Photography: carbohyrazide is used in the silver halide diffusion process as one of the toners.
Carbohydrazide is used to stabilize color developers that produce images of the azo-methine and azine classes.
Carbohydrazide has been used to develop ammunition propellants, stabilize soaps, and used a reagent in organic synthesis.
Heating carbohydrazide may result in an explosion.
Carbohydrazide is harmful if swallowed, irritating to eyes, respiratory system, and skin.
Carbohydrazide is toxic to aquatic organisms.
Dissolved oxygen is a prime contributor to corrosion in power plant steam cycles and the use of oxygen scavengers is one way to keep it as low as possible.
DO2 (dissolved oxygen) is a prime contributor to corrosion in power plant steam cycles and is affected by a number of design and chemistry related parameters.
Correct plant operations and reliable instrumentation information contribute to maintain low oxygen levels.
The addition of oxygen scavengers is one solution that is commonly applied to meet this goal.
There are many criteria for the choice of a specific scavenger.
The first criteria is that it should not generate solids, which can either damage turbine blades or generate deposits in heat exchangers with thermal transfer decrease.
The consequence is to look first for organic, non-solid scavengers.
Other criteria of interest are:
¢ Quick reaction efficiency at any temperature
¢ No carcinogenic risk or special handling
¢ Good thermal stability at high temperature
¢ No by-products generated in the condensate circuit, promotion to the formation of a passivating metal film
¢ No interaction with other chemicals used, no reaction with materials
¢ No contribution to lowering the pH to corrosive levels (pH<8)
¢ Low cost
The carbohydrazide is a white crystalline solid with a melting point of 153°C.
It decomposes upon melting and is highly water soluble.
1. Indirect reaction (> 180°C) (N2 H3 )2CO + H2 O i 2N2 H4 + CO2 2N2 H4 + 2O2 i 4H2 O + 2N2
2. Decomposition (> 200°C) (N2 H3 )2CO + H2 O i 2NH3 + N2 + H2 + CO2 The theoretical dosage required to scavenge one part DO2 is 1.4 parts carbohydrazide.
Many of the same benefits of hydrazine are provided but without the carcinogen risk: ammonia generation with pH increase and efficient corrosion protection, magnetite creation as protective layer.
For these reasons, carbohydrazide is a good alternative to hydrazine.
Dosification and measuring spots
Oxygen scavengers injection and measurement are carried out where DO2 concentrations can be found:
¢ Polishing plant outlet
¢ Condensates pump discharge.
Condensate are the major source of contamination because they may be in contact with the external source of pollution (raw water) when there are condenser tube leaks.
Oxygen scavengers are added to the deaerated boiler feedwater to remove the last traces of oxygen that were not removed by the de-aerator
For optimising the efficiency of the boiler, extending its lifespan and ensuring the steam quality, quality requirements of feed water are essential.
The scavenger avoids the pre-boiler corrosion risks. The quantity of oxygen scavenger to inject is either:
Determined from the initial DO2 content at the deaerator outlet (before the scavenger addition).
Theoretically, 1.0 ppb of hydrazine is required to react with 1.0 ppb of dissolved oxygen, however, in practice 1.5-2.0 parts of hydrazine are injected per part of oxygen.
Generally [N2 H4 ]= initial [DO2 ] x 3 ¢ Fixed to obtain a minimum residual hydrazine concentration. Generally, residual [DO2 ] +7 to 10μg/l.
Continuous analysis of DO2 is combined with oxygen scavenger and made on the boiler feed water, de-aerator outlet and the condensate discharge.
Injection is done via dosing pumps with a solution at 35%.
At temperatures below 150°C the reaction with oxygen is very slow, the use of hydroquinone as catalyst increases the reaction rate from 10 to 100 times.
Carbohydrazide reacts with dissolved oxygen to produce water and carbon dioxide as shown in the following reaction formula.
Carbohydrazide is known to have a higher dissolved oxygen removal rate than hydrazine up to 85 ° C.
It hydrolyzes to 150 ° C to generate hydrazine and carbon dioxide, and decomposes to ammonia, nitrogen and hydrogen at temperatures above 200 ° C.
Unlike hydrazine, however, carbohydrazide is not recognized as a carcinogen and is less toxic than hydrazine.
Carbazic acid, hydrazide
Carbonic acid, dihydrazide
Hydrazinecarboxylic acid, hydrazide
hydrazide hydrazinecarboxylic acid
Carbohydrazide, which is marketed under different trade names, was believed to be a good alternative to hydrazinethat provides all of the additional benefits desired of an alternative oxygen scavenger of being safe to handle but without the deleterious impact on the cycle chemistry.
When used as de-oxidant in boiler, put this product into water or use its water solution, the dosage of 0.5mol or above of carbohydrazide for 1mol O2 is preferred.
The suitable temperature range is 87.8-176.7℃. The reaction for carbohydrazide with O2 is CON4H6+ 2O2= 2N2 + 3H2O + CO2
Carbohydrazide is added to boiler system water as an oxygen scavenger to control corrosion.
Carbohydrazide is a safer alternative to hydrazine, which is toxic.
Carbohydrazide reacts with oxygen at low temperatures and pressures.
The products of the reaction are volatile and do not contribute dissolved solids to the boiler water.
Like hydrazine, carbohydrazide will also passivate metal surfaces.
Other names: Carbonic dihydrazide; Carbazide; Carbodihydrazide; Carbonic acid, dihydrazide; Carbonohydrazide; Hydrazine, carbonylbis-; Hydrazinecarboxamide, N-amino-; Hydrazinecarboxylic acid, hydrazide; Urea, N,N'-diamino-; Carbazic acid, hydrazide; Hydrazine, carbonyldi-; Semicarbazide, 4-amino-; Urea, 1,3-diamino-; 1,3-Diaminourea; Cabazide; 1,3-Diaminomocovina; Karbazid; NSC 1934
NOTES: Carbohydrazide is a good oxygen scavenger for use in water treatment applications, especially for protecting boiler feed systems.
It is also commony used as a specialty chemical intermediate in organic synthesis.
CLASS: Specialty Chemicals, Chemical Intermediates, Organic Intermediates and Compounds, Water Treatment Chemicals, Industrial Chemicals
FUNCTIONS: Intermediates,Chemical Intermediate
INDUSTRY: Industrial, Water Treatment, Specialty Chemicals
BENEFITS OF CARBOHYDRAZIDE
Carbohydrazide is an oxygen scavenger that contributes no inorganic solids to the feed water or boiler water
Carbohydrazide is an oxygen scavenger that DOES NOT decomposes in organic acid species
Carbohydrazide contributes to passivation
Carbohydrazide controls oxygen corrosion
Efficient operation of boilers and other steam-run equipment requires chemical treatment of feed water to control corrosion.
Corrosion in such systems usually arises as a result of oxygen attack on steel in water supply equipment, pre-boiler systems, boiler and condensate return lines.
Unfortunately, oxygen attack on steel is accelerated by the unavoidably high temperatures found in boilers.
In most modern boiler systems, dissolved oxygen is handled firstly mechanically and then chemically scavenging the remainder.
Chemical scavenging of the remaining dissolved oxygen is widely accomplished by treating the water with Hydrazine.
However, Hydrazine is recognized as an extremely toxic chemical and possesses severe health threats.
Carbohydrazide based oxygen scavenger contains corrosion owing to dissolved oxygen, without adding any inorganic solids to the boiler water.
This particular class of oxygen scavenger does not decompose into organic acid species and works by promoting the formation of passivating metal oxide films without interfering with the action of other treatment chemicals.
It minimizes oxygen induced corrosion and pitting, iron oxide deposition and scaling of feed-water lines, de-aerators, and internal steam boiler with these advanced boiler oxygen scavengers.
This boiler water treatment is mainly available in two variants - powder and liquid.
In solid form, it is white crystalline in appearance, completely soluble in water, decomposes around 153°C/ 307.4 F.
The liquid variant is based on volatile chemistry which leaves no dissolved solids, and ammonia to the boiler system.
Carbohydrazide prevents corrosion by forming a protective passive film on metal and boosting pH in condensate line, thereby increasing the shelf-life of boilers.
Although it may be added to the boiler system at any point, it is most efficient to treat the boiler feed water, preferably as it comes from the de-gasifiers.
Residence times prior to steam formation should be maximized to obtain maximum corrosion protection.
Carbohydrazide is an effective oxygen scavenger and metal passivator over the entire range of temperatures to which the boiler is generally subjected.
Key Features and Benefits of this Boiler Water Treatment:
Long time protection and control against corrosion
Non carcinogenic nature
Easy to dose
Promotes passivation on metal surfaces
Carbohydrazide is an urea derivative in which both the amide groups of urea have been replaced by hydrazine residues.
It is a white crystals; melting point 153 C; very soluble in alcohol and water.
Chemical oxygen scavengers are used to scavenge remaining oxygen water to prevent the corrosion in the closed water system.
Oxygen scavengers include several organic and inorganic types such as hydrazine, hydroquinone, diethylhydroxyethanol, oximes, and sulfites.
Sulfite reacts with remaining oxygen and forms sulfate. Hydrazine reacts with remaining oxygen to generate water and nitrogen.
Carbohydrazide, an analogue of hydrazine, is used to replace hydrazine which is associated safety hazards and handling precautions.
Carbohydrazide can be used when thermal and pressure stability is required such as in boiler feed system.
Carbohydrazide is used as an auxiliary in photographic industry to prevent discolouration.
It is used as an intermediate for pharmaceuticals, stabilizers and water treatment chemicals.