Difference between revisions of "Urea"

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'''Urea''' or '''carbamide''', is an organic compound commonly used as a fertilizer. It has the chemical formula (NH<sub>2</sub>)<sub>2</sub>CO. Urea was the first organic chemical produced from inorganic chemicals, a breakthrough in chemistry, which proved organic substances can be produced from inorganic substances, disproving the notion of vitalism.
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| Name = Urea
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| Reference =
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| IUPACName = Urea
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| PIN =
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| SystematicName = Carbonic diamide
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| OtherNames = Carbamide<br>Carbonyl diamide<br>Carbonyldiamine<br>Diaminomethanal<br>Diaminomethanone
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| ImageFile = Urea.jpg
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| ImageSize = 270
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| ImageCaption = Urea crystals obtained from AdBlue
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| ImageFile1 = Urea ball and stick.png
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| ImageCaption1 = Ball and stick model of urea.
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| Section1 = {{Chembox Identifiers
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| 3DMet =
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| Abbreviations =
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| SMILES =
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| Section2 = {{Chembox Properties
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| AtmosphericOHRateConstant =
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| Appearance = White solid
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| BoilingPt =
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| BoilingPtC =
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| BoilingPt_ref =
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| BoilingPt_notes = Decomposes
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| Density = 1.32 g/cm<sup>3</sup>
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| Formula = CH<sub>4</sub>N<sub>2</sub>O<br>(NH<sub>2</sub>)<sub>2</sub>CO
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| HenryConstant =
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| LogP =
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| MolarMass = 60.06 g/mol
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| MeltingPt =
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| MeltingPtC = 133 - 135
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| MeltingPt_ref =
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| MeltingPt_notes =
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| pKa =
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| pKb =
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| Solubility = 107.9 g/100 ml (20 °C)<br>167 g/100 ml (40 °C)<br>251 g/100 ml (60 °C)<br>400 g/100 ml (80 °C)
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| SolubleOther = Soluble in glacial [[acetic acid]]<br>Insoluble in [[benzene]], [[toluene]], [[xylene]]
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| Solubility1 = 0.4 g/100 ml
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| Solvent1 = acetonitrile
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| Solubility2 = 5 g/100 ml
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| Solvent2 = ethanol
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| Solubility3 = 50 g/100 ml
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| Solvent3 = glycerol
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| Solubility4 = 16.6 g/100 ml
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| Solvent4 = methanol
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| VaporPressure =
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| Section4 = {{Chembox Thermochemistry
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| DeltaGf = -47.12 kcal/mol
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| DeltaHc =
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| DeltaHf = -79.634 kcal/mol
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| HeatCapacity =
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| Section6 = {{Chembox Hazards
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| AutoignitionPt =
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| ExternalMSDS = [https://www.docdroid.net/X15Opy8/urea-sa.pdf.html Sigma-Aldrich]
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| LD50 = 8500 mg/kg (oral, rat)
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| LC50 =
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| MainHazards = Irritant
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| Section7 = {{Chembox Related
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| OtherCompounds = [[Biuret]]
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'''Urea''' or '''carbamide''', is an organic compound commonly used as a fertilizer. It has the chemical formula '''(NH<sub>2</sub>)<sub>2</sub>CO'''. Urea was the first organic chemical produced from inorganic chemicals, a breakthrough in chemistry, which proved organic substances can be produced from inorganic substances, disproving the notion of vitalism.
  
 
==Properties==
 
==Properties==
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:NH<sub>2</sub>CONH<sub>2</sub> → NH<sub>4</sub>NCO → HNCO + NH<sub>3</sub>
 
:NH<sub>2</sub>CONH<sub>2</sub> → NH<sub>4</sub>NCO → HNCO + NH<sub>3</sub>
  
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Urea is a weak organic base. It forms salts with strong acids. Despite its two amino groups, it acts as a monoprotic base, only accepting one H+ cation. With diprotic acids such as sulfuric, urea forms two types of salts: monocarbamide dihydrosulfate (carbamonium bisulfate, analogous to inorganic bisulfates) and dicarbamide dihydrosulfate (carbamonium sulfate, analogous to inorganic sulfates).
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Urea is a weak organic base. It forms salts with strong acids.<ref>
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https://books.google.com/books?id=Y87aAAAAMAAJ&pg=PA12&lpg=PA12&dq=urea+tartrate&source=bl&ots=PYI2nVC-By&sig=7IbwzeNy5bCPdVWiKmzSzQzq7mw&hl=en&sa=X&sqi=2&ved=0ahUKEwimvPTNmKDLAhXCdx4KHaUGDfkQ6AEIMzAE#v=onepage&q=urea%20tartrate&f=false</ref>  Despite its two amino groups, it acts as a monoprotic base, only accepting one H+ cation. With diprotic acids such as sulfuric, urea forms two types of salts: monocarbamide dihydrosulfate (carbamonium bisulfate, analogous to inorganic bisulfates) and dicarbamide dihydrosulfate (carbamonium sulfate, analogous to inorganic sulfates).
  
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A frequent contaminant of urea is [[Biuret]].  A high concentration of Biuret mitigates against using urea as a crop fertilizer, but makes it more valuable as an animal feed additive.
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A frequent contaminant of urea is [[biuret]].  A high concentration of biuret mitigates against using urea as a crop fertilizer, but makes it more valuable as an animal feed additive.
  
 
===Physical===
 
===Physical===
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Urea is a white crystalline substance. Its melting point is between 133-135 °C. Urea is soluble in water (107.9 g/100 ml at 20 °C) and when dissolved, it is neutral on the pH scale. Urea is soluble in [[glycerol]] (500 g/L) and slightly less soluble in [[ethanol]].
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Urea is a white crystalline substance. Its melting point is between 133-135 °C. Urea is soluble in water (107.9 g/100 ml at 20 °C) and when dissolved, it is neutral on the pH scale. Urea is soluble in [[glycerol]] (500 g/L) and slightly less soluble in [[ethanol]]. Urea is soluble in [[dimethyl sulfoxide]] (40 g/100 ml at 20-30 °C, 110 g/100 ml at 90-100 °C).  <ref>http://www.gaylordchemical.com/uploads/images/pdfs/literature/102B_english.pdf Gaylord Chemical Company</ref>
  
 
==Availability==
 
==Availability==
−
Urea is available as a fertilizer, either pure or mixed with other substances. It can be very cheaply purchased online, often at less than $5/kg.  
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Urea is available as a fertilizer, either pure or mixed with other substances. It can be very cheaply purchased online, often at less than $5/kg. Most of the OTC urea is coated with a special coating which slows its release in the soil, to prevent fertilizer burn. Recrystallization is required to remove this coating.
  
 
[http://www.sciencecompany.com/Urea-500g-P16216.aspx ScienceCompany] sells 500g of lab grade urea at 16.95 $.
 
[http://www.sciencecompany.com/Urea-500g-P16216.aspx ScienceCompany] sells 500g of lab grade urea at 16.95 $.
  
 
Ebay has many listings for urea as a [http://www.ebay.com/sch/Lab-Chemicals-/104233/i.html?_from=R40&_nkw=urea&_sop=15 lab chemical] and as [http://www.ebay.com/sch/Fertilizers-/119683/i.html?_from=R40&_nkw=urea&_sop=15 fertilizer]
 
Ebay has many listings for urea as a [http://www.ebay.com/sch/Lab-Chemicals-/104233/i.html?_from=R40&_nkw=urea&_sop=15 lab chemical] and as [http://www.ebay.com/sch/Fertilizers-/119683/i.html?_from=R40&_nkw=urea&_sop=15 fertilizer]
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AdBlue, used for reduction of nitrous oxide gases from car exhausts, is a quite strong solution of urea in water with little other additives.
  
 
==Preparation==
 
==Preparation==
 
Urea was first synthesized by reacting [[silver cyanate]] with [[ammonium chloride]].
 
Urea was first synthesized by reacting [[silver cyanate]] with [[ammonium chloride]].
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:AgNCO + NH<sub>4</sub>Cl → (NH<sub>2</sub>)<sub>2</sub>CO + AgCl
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:AgOCN + NH<sub>4</sub>Cl → (NH<sub>2</sub>)<sub>2</sub>CO + AgCl
  
 
Industrially it is produced by the thermal decomposition of [[ammonium carbamate]].
 
Industrially it is produced by the thermal decomposition of [[ammonium carbamate]].
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==Reactions==
 
==Reactions==
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Urea forms many adducts with acids and other inorganic and organic compounds. It also acts as a source of ammonia in certain reactions, such as in the production of [[amide]]s and [[citrazinic acid]].
  
 
{|  class="wikitable collapsible collapsed" width="100%" border="0"
 
{|  class="wikitable collapsible collapsed" width="100%" border="0"
 
!Urea reacts with:|| catalyst|| solvent || product || reaction notes  
 
!Urea reacts with:|| catalyst|| solvent || product || reaction notes  
 
|- style="border=1 cellpadding=2"
 
|- style="border=1 cellpadding=2"
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| [[nitric acid]]||  || water || [[urea nitrate]] || exothermic
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| [[Nitric acid]]||  || water || [[urea nitrate]] || exothermic
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|-
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| [[Potassium nitrate]] <ref>[http://www.angelfire.com/empire/megapyro6/Pyro/UN.html Making Urea Nitrate without Nitric Acid]</ref> || [[hydrochloric acid]] || water|| [[urea nitrate]] || replacement
 +
|-
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| [[Hydrogen peroxide]] || ||water|| [[urea peroxide]] || exothermic
 
|-
 
|-
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| [[potassium nitrate]] <ref>[http://www.angelfire.com/empire/megapyro6/Pyro/UN.html Making Urea Nitrate without Nitric Acid]</ref> || [[hydrochloric acid]] || water|| [[urea nitrate]] || replacement
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| [[Citric acid]] <ref>http://link.springer.com/article/10.1007/s11167-005-0579-2#page-1</ref> || || water || [[urea citrate]] ||
 
|-
 
|-
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| [[hydrogen peroxide]] || ||water|| [[urea peroxide]] || exothermic
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| [[Sodium carbonate]] || || water || [[sodium cyanate]] || produces ammonia gas
 
|-
 
|-
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| [[citric acid]] <ref>http://link.springer.com/article/10.1007/s11167-005-0579-2#page-1</ref> || || water || [[urea citrate]] ||
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| [[Malonic acid]] and [[sodium ethoxide]] || ||anhydrous [[ethanol]] || [[barbituric acid]] || condensation
 
|}
 
|}
  
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*[[Sodium azide]] synthesis
 
*[[Sodium azide]] synthesis
 
*[[Hydrazine sulfate]](Hoffman Rearrangement)
 
*[[Hydrazine sulfate]](Hoffman Rearrangement)
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*[[Calcium cyanamide]] synthesis
 
*Thermal decomposition of molten urea to biuret and ammonia.
 
*Thermal decomposition of molten urea to biuret and ammonia.
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*Make sodium cyanate and [[sodium cyanide]]
  
 
==Handling==
 
==Handling==
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===Storage===
 
===Storage===
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Urea doesn't require any special storage, and can be safely stored in glass, metal, plastic or ceramic containers.
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Urea doesn't require any special storage, and can be safely stored in glass, metal, plastic or ceramic containers. Make sure to keep it in a dry place, as urea will absorb water from air and harden itself after a while, if kept in a moist place.
  
 
===Disposal===
 
===Disposal===
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===Relevant Sciencemadness threads===
 
===Relevant Sciencemadness threads===
 
*[http://www.sciencemadness.org/talk/viewthread.php?tid=3386 Urea Synthesis]
 
*[http://www.sciencemadness.org/talk/viewthread.php?tid=3386 Urea Synthesis]
 +
*[http://www.sciencemadness.org/talk/viewthread.php?tid=63013 Recrystallation of Fertilizer Grade Urea]
  
 
[[Category:Chemical compounds]]
 
[[Category:Chemical compounds]]
 
[[Category:Organic compounds]]
 
[[Category:Organic compounds]]
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[[Category:Nitrogen compounds]]
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[[Category:Amines]]
 
[[Category:Bases]]
 
[[Category:Bases]]
 
[[Category:Organic bases]]
 
[[Category:Organic bases]]
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[[Category:Ureas]]
 
[[Category:Readily available chemicals]]
 
[[Category:Readily available chemicals]]
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[[Category:Essential reagents]]

Latest revision as of 13:27, 10 July 2022

Urea
Urea.jpg
Urea crystals obtained from AdBlue
Urea ball and stick.png
Ball and stick model of urea.
Names
IUPAC name
Urea
Systematic IUPAC name
Carbonic diamide
Other names
Carbamide
Carbonyl diamide
Carbonyldiamine
Diaminomethanal
Diaminomethanone
Properties
CH4N2O
(NH2)2CO
Molar mass 60.06 g/mol
Appearance White solid
Density 1.32 g/cm3
Melting point 133–135 °C (271–275 °F; 406–408 K)
Boiling point Decomposes
107.9 g/100 ml (20 °C)
167 g/100 ml (40 °C)
251 g/100 ml (60 °C)
400 g/100 ml (80 °C)
Solubility Soluble in glacial acetic acid
Insoluble in benzene, toluene, xylene
Solubility in acetonitrile 0.4 g/100 ml
Solubility in ethanol 5 g/100 ml
Solubility in glycerol 50 g/100 ml
Solubility in methanol 16.6 g/100 ml
Thermochemistry
-79.634 kcal/mol
Hazards
Safety data sheet Sigma-Aldrich
Lethal dose or concentration (LD, LC):
8500 mg/kg (oral, rat)
Related compounds
Related compounds
 Biuret
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Urea or carbamide, is an organic compound commonly used as a fertilizer. It has the chemical formula (NH2)2CO. Urea was the first organic chemical produced from inorganic chemicals, a breakthrough in chemistry, which proved organic substances can be produced from inorganic substances, disproving the notion of vitalism.

Properties

Chemical

Thermal decomposition of urea produces ammonium isocyanate, who in turn yields isocyanuric acid.

NH2CONH2 → NH4NCO → HNCO + NH3

Urea is a weak organic base. It forms salts with strong acids.[1] Despite its two amino groups, it acts as a monoprotic base, only accepting one H+ cation. With diprotic acids such as sulfuric, urea forms two types of salts: monocarbamide dihydrosulfate (carbamonium bisulfate, analogous to inorganic bisulfates) and dicarbamide dihydrosulfate (carbamonium sulfate, analogous to inorganic sulfates).

A frequent contaminant of urea is biuret. A high concentration of biuret mitigates against using urea as a crop fertilizer, but makes it more valuable as an animal feed additive.

Physical

Urea is a white crystalline substance. Its melting point is between 133-135 °C. Urea is soluble in water (107.9 g/100 ml at 20 °C) and when dissolved, it is neutral on the pH scale. Urea is soluble in glycerol (500 g/L) and slightly less soluble in ethanol. Urea is soluble in dimethyl sulfoxide (40 g/100 ml at 20-30 °C, 110 g/100 ml at 90-100 °C). [2]

Availability

Urea is available as a fertilizer, either pure or mixed with other substances. It can be very cheaply purchased online, often at less than $5/kg. Most of the OTC urea is coated with a special coating which slows its release in the soil, to prevent fertilizer burn. Recrystallization is required to remove this coating.

ScienceCompany sells 500g of lab grade urea at 16.95 $.

Ebay has many listings for urea as a lab chemical and as fertilizer

AdBlue, used for reduction of nitrous oxide gases from car exhausts, is a quite strong solution of urea in water with little other additives.

Preparation

Urea was first synthesized by reacting silver cyanate with ammonium chloride.

AgOCN + NH4Cl → (NH2)2CO + AgCl

Industrially it is produced by the thermal decomposition of ammonium carbamate.

It can also be produced from the reaction of phosgene and ammonia

COCl2 + 4 NH3 → (NH2)2CO + 2 NH4Cl

Reactions

Urea forms many adducts with acids and other inorganic and organic compounds. It also acts as a source of ammonia in certain reactions, such as in the production of amides and citrazinic acid.

Projects

Handling

Safety

Urea is non-toxic, though is may cause irritations to sensitive tissues. It may corrode metallic surfaces, even the more resistant forms of stainless steel.

Storage

Urea doesn't require any special storage, and can be safely stored in glass, metal, plastic or ceramic containers. Make sure to keep it in a dry place, as urea will absorb water from air and harden itself after a while, if kept in a moist place.

Disposal

As urea is a good fertilizer, it can be safely dumped in the soil, although it's recommended to avoid dumping it in water reservoirs to prevent the growth on unwanted algae. It can also be used to as a nitrogen source for aerobic bacteria in the conversion of sawdust to compost.

References

  1. ↑ https://books.google.com/books?id=Y87aAAAAMAAJ&pg=PA12&lpg=PA12&dq=urea+tartrate&source=bl&ots=PYI2nVC-By&sig=7IbwzeNy5bCPdVWiKmzSzQzq7mw&hl=en&sa=X&sqi=2&ved=0ahUKEwimvPTNmKDLAhXCdx4KHaUGDfkQ6AEIMzAE#v=onepage&q=urea%20tartrate&f=false
  2. ↑ http://www.gaylordchemical.com/uploads/images/pdfs/literature/102B_english.pdf Gaylord Chemical Company
  3. ↑ Making Urea Nitrate without Nitric Acid
  4. ↑ http://link.springer.com/article/10.1007/s11167-005-0579-2#page-1

Relevant Sciencemadness threads

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