2,4-Dinitrophenylhydrazine

2007-12-06T14:27:48Z

Seg06:

<noinclude>

</noinclude>{| class="toccolours" border="1" style="float: right; clear: right; margin: 0 0 1em 1em; border-collapse: collapse; width: 280px"
! {{chembox header}} | {{PAGENAME}} 
|-
| align="center" colspan="2" bgcolor="#ffffff" | [[Image:2,4-dnph.png|200px|{{PAGENAME}}]] 
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|-
! {{chembox header}} | General
|-
| [http://en.wikipedia.org/wiki/IUPAC Systematic name]
| 2,4-Dinitrophenylhydrazine

|-
| Other names
| 2,4-DNPH, Brady's Reagent
|-
| [http://en.wikipedia.org/wiki/Chemical_formula Molecular formula]
| C6H6N4O4
|-
| [http://en.wikipedia.org/wiki/Chemical_file_format SMILES] 
| [H]N([H])N([H])C1=CC=C([N+]
[O-])=O)C=C1[N+]([O-])=O
|-
| [http://en.wikipedia.org/wiki/Molar_mass Molar mass]
| 198.14
|-
| Appearance
| wet, red or orange, crystalline powder
|-
| [http://en.wikipedia.org/wiki/CAS_registry_number CAS number]
| 119-26-6
|-
! {{chembox header}} | Properties
|-
| [http://en.wikipedia.org/wiki/Solubility Solubility in water]
| slight solubility in water
|-
| [http://en.wikipedia.org/wiki/Melting_point Melting point]
| 200-202°C (473-475K) decomposes
|-
! {{chembox header}} | Hazards 
|-
| Main [[Worker safety and health|hazard]]s
| [[image:2,4-dnph-hazard.png|210px|hazard symbols of 2,4-DNPH]]
potential carcinogen
|-
| {{chembox header}} | Except where noted otherwise, data are given for materials in their [[standard state|standard state (at 25 °C, 100 kPa)]] [[wikipedia:Chemical infobox|Infobox disclaimer and references]]
|-
|}

''This article is about the compound 2,4-Dinitrophenylhydrazine, otherwise known as 2,4-DNPH or Brady's Reagent. It is a substituted hydrazine (NH2NH2) and is most commonly used as a qualitative test for the presence of the carbonyl functional group (C=O).''

=Synthesis=

2,4-DNPH can be synthesized via the electrophilic substitution reaction of hydrazine with 2,4-dinitrochlorobenzene. This synthesis was carried out by C. F. H. Allen in 1943<ref>C.F.H Allen, ''Organic Syntheses'', '''1943''', 2, p228.</ref>. The reaction scheme of this reaction is shown below.

[[Image:2,4-dnph-synthesis.png|Synthesis of 2,4-DNPH]]

==Alternative Methods of Synthesis==

Besides using hydrazine, the synthesis of 2,4-dinitrophenylhydrazine has also been carried out using hydrazine hydrate<ref>O.L. Brady;G.V. Elsmie, ''Analyst'', '''1926''', 51, p77</ref> (OH2-H2N-NH2) and hydrazine acetate (NH2NH2)(CH3COOH). On top of that, the 2,4-dinitrochlorobenzene reagent can be replaced with its respective bromine derivative.

=Reaction with Carbonyl Compounds=

2,4-dinitrophenylhydrazine, having a nitrogen atom with lone pairs, is an effective nucleophile. On the other hand, carbonyl compounds, with the polarized carbon-oxygen double bonds, have electrophilic carbon centres. As such, it is no surprise that 2,4-dinitrophenylhydrazine will react readily with carbonyl compounds in a condensation reaction, more specifically known as the Brady's Reaction. The overall reaction scheme and mechanism of this reaction is shown below.

[[Image:2,4-dnph-mechanism.png|550px|Mechanism for Reaction of 2,4-DNPH with carbonyl compounds]]

In chemical experiments, the solid 2,4-DNPH is first dissolved in a methanol/sulphuric acid solvent to give a yellow solution of 2,4-DNPH. This solution is what we call Brady's Reagent. A few drops of carbonyl compound is then added to Brady's Regeant and the reaction will proceed smoothly with no need for heating or any other reagents.

The products obtained from this reaction are water and an organic compound which is known as a dinitrophenylhydrazone. In general, a hydrazone is a class of organic compound which contains the C=N double bond, with the general formula of R2C=NR2. As water is eliminated in the Brady's Reaction, we can see why this reaction is also considered a condensation reaction. In terms of mechanism, this reaction proceeds via a ''nucleophilic addition-elimination'' mechanism. The 2,4-DNPH first adds across the carbon-oxygen double bond to form an intermediate, which then gives the final product upon the elimination of a water molecule.

[[Image:2,4-ppt.jpg|thumb|Positive test of 2,4-DNPH with the carbonyl group (Right) <ref>http://acpcommunity.acp.edu/facultystaff/genchem/GC1/lab/qual/dnp.jpg</ref>]]

==Using the Brady's Reaction==

As mentioned above, 2,4-dinitrophenylhydrazine is mainly used as a positive test for the presence of a carbonyl functional group. The addition of Brady's Reagent to a compound containing the carbonyl functional group will result in the formation of a dinitrophenylhydrazone, which is actually an orange or yellow insoluble solid. As such, with just a simple addition of a few drops of 2,4-DNPH, we are able to tell whether a carbon-oxygen double bond is present, by observing the formation (or absence) of a yellow/orange precipitate. As other functional groups will not react with the hydrazine, Brady's reagent is one of the most useful substances that enable chemists to distinguish aldehydes and ketones from other functional groups.

==Dinitrophenylhydrazones==

Besides just testing for the presence of the carbon-oxygen double bond, the Brady's Reaction can also be used to identify the specific aldehyde or ketone. The precipitate obtained is usually filtered, washed (for example, with methanol) and then recrystallised from a suitable solvent. The solvent used will vary depending on the nature of the carbonyl compound involved. For example, the hydrazones from smaller aldehydes and ketones can be recrystallised from a mixture of ethanol and water.

The 2,4-DNPH derivatives obtained from the reaction of 2,4-DNPH with the various carbonyl compounds have distinct characteristic colours and melting points. There are data tables which show the melting points of the derivatives of common aldehydes and ketones. As such, by finding the melting point of the crystals obtained after recrystallisation, it is possible to identify the carbonyl compound by comparing it with tables of known melting points to find out which carbonyl compound you are likely to have. Some examples of aldehydes and ketones and the melting points of their respective hydrazones are given below.

{| class="wikitable" style="margin: 1em auto 1em auto;text-align:center; background:silver" border="1" cell-padding=5
|- style="background:silver"
| width=200 | ''' Ketone ''' || width=50 | ''' BP/°C ''' || width=200| ''' MP of 2,4-DNP derivative/°C ''' || style="background:silver" | || style="background:silver" | || style="background:silver" | || width=200| '''Aldehyde''' || width=50 | '''BP/°C''' || width=200| '''MP of 2,4-DNP derivative/°C'''
|- style="background:white"
| Acetone (Propanone) || 56 || 128 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Propanal || 48|| 150
|- style="background:white"
| Butanone || 82 || 117 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Butanal || 75 || 123
|- style="background:white"
| 3-pentanone || 102 || 156 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Pentanal || 103 || 98
|- style="background:white"
| Cyclohexanone || 156|| 162 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Hexanal|| 131 || 104
|- style="background:white"
| 1-Phenyl-2-propanone || 216 || 191 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Benzaldehyde|| 179 || 237

|}

=Similar Addition-Elimination Reactions=

[[image: general.png|thumb|left|general equation for addition-elimination reactions involving nitrogen]]

The reaction between 2,4-dinitrophenylhydrazine and carbonyl compounds is actually a very common reaction. It can be observed from the reaction scheme that only the NH2 part of the molecule reacts and the rest remain unchanged. If the NH2 group is attached to other things, similar reactions can also occur via the same mechanism. Some examples of such reactions are shown below<ref>MSU Department of Chemistry, ''Virtual Textbook of Organic Chemistry'', http://www.cem.msu.edu/%7Ereusch/VirtualText/aldket1.htm#rx1</ref> In each reaction, water is lost (condensation process) and a C=N double bond is formed, giving different functional groups in the final products. These reactions are very useful for functional group interconversions.

[[image:similarreactions.png|examples of similiar addition-elimination reactions]]

=References=
<references />

2,4-Dinitrophenylhydrazine

2007-12-06T14:01:30Z

Seg06: /* Similar Addition-Elimination Reactions */

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|-
! {{chembox header}} | General
|-
| [http://en.wikipedia.org/wiki/IUPAC Systematic name]
| 2,4-Dinitrophenylhydrazine

|-
| Other names
| 2,4-DNPH, Brady's Reagent
|-
| [http://en.wikipedia.org/wiki/Chemical_formula Molecular formula]
| C6H6N4O4
|-
| [http://en.wikipedia.org/wiki/Chemical_file_format SMILES] 
| [H]N([H])N([H])C1=CC=C([N+]
[O-])=O)C=C1[N+]([O-])=O
|-
| [http://en.wikipedia.org/wiki/Molar_mass Molar mass]
| 198.14
|-
| Appearance
| wet, red or orange, crystalline powder
|-
| [http://en.wikipedia.org/wiki/CAS_registry_number CAS number]
| 119-26-6
|-
! {{chembox header}} | Properties
|-
| [http://en.wikipedia.org/wiki/Solubility Solubility in water]
| slight solubility in water
|-
| [http://en.wikipedia.org/wiki/Melting_point Melting point]
| 200-202°C (473-475K) decomposes
|-
! {{chembox header}} | Hazards 
|-
| Main [[Worker safety and health|hazard]]s
| [[image:2,4-dnph-hazard.png|210px|hazard symbols of 2,4-DNPH]]
potential carcinogen
|-
| {{chembox header}} | Except where noted otherwise, data are given for materials in their [[standard state|standard state (at 25 °C, 100 kPa)]] [[wikipedia:Chemical infobox|Infobox disclaimer and references]]
|-
|}

''This article is about the compound 2,4-Dinitrophenylhydrazine, otherwise known as 2,4-DNPH or Brady's Reagent. It is a substituted hydrazine (NH2NH2) and is most commonly used as a qualitative test for the presence of the carbonyl functional group (C=O).''

=Synthesis=

2,4-DNPH can be synthesized via the electrophilic substitution reaction of hydrazine with 2,4-dinitrochlorobenzene. This synthesis was carried out by C. F. H. Allen in 1943<ref>C.F.H Allen, ''Organic Syntheses'', '''1943''', 2, p228.</ref>. The reaction scheme of this reaction is shown below.

[[Image:2,4-dnph-synthesis.png|Synthesis of 2,4-DNPH]]

==Alternative Methods of Synthesis==

Besides using hydrazine, the synthesis of 2,4-dinitrophenylhydrazine has also been carried out using hydrazine hydrate<ref>O.L. Brady;G.V. Elsmie, ''Analyst'', '''1926''', 51, p77</ref> (OH2-H2N-NH2) and hydrazine acetate (NH2NH2)(CH3COOH). On top of that, the 2,4-dinitrochlorobenzene reagent can be replaced with its respective bromine derivative.

=Reaction with Carbonyl Compounds=

2,4-dinitrophenylhydrazine, having a nitrogen atom with lone pairs, is an effective nucleophile. On the other hand, carbonyl compounds, with the polarized carbon-oxygen double bonds, have electrophilic carbon centres. As such, it is no surprise that 2,4-dinitrophenylhydrazine will react readily with carbonyl compounds in a condensation reaction, more specifically known as the Brady's Reaction. The overall reaction scheme and mechanism of this reaction is shown below.

[[Image:2,4-dnph-mechanism.png|550px|Mechanism for Reaction of 2,4-DNPH with carbonyl compounds]]

In chemical experiments, the solid 2,4-DNPH is first dissolved in a methanol/sulphuric acid solvent to give a yellow solution of 2,4-DNPH. This solution is what we call Brady's Reagent. A few drops of carbonyl compound is then added to Brady's Regeant and the reaction will proceed smoothly with no need for heating or any other reagents.

The products obtained from this reaction are water and an organic compound which is known as a dinitrophenylhydrazone. In general, a hydrazone is a class of organic compound which contains the C=N double bond, with the general formula of R2C=NR2. As water is eliminated in the Brady's Reaction, we can see why this reaction is also considered a condensation reaction. In terms of mechanism, this reaction proceeds via a ''nucleophilic addition-elimination'' mechanism. The 2,4-DNPH first adds across the carbon-oxygen double bond to form an intermediate, which then gives the final product upon the elimination of a water molecule.

[[Image:2,4-ppt.jpg|thumb|Positive test of 2,4-DNPH with the carbonyl group (Right) <ref>http://acpcommunity.acp.edu/facultystaff/genchem/GC1/lab/qual/dnp.jpg</ref>]]

==Using the Brady's Reaction==

As mentioned above, 2,4-dinitrophenylhydrazine is mainly used as a positive test for the presence of a carbonyl functional group. The addition of Brady's Reagent to a compound containing the carbonyl functional group will result in the formation of a dinitrophenylhydrazone, which is actually an orange or yellow insoluble solid. As such, with just a simple addition of a few drops of 2,4-DNPH, we are able to tell whether a carbon-oxygen double bond is present, by observing the formation (or absence) of a yellow/orange precipitate. As other functional groups will not react with the hydrazine, Brady's reagent is one of the most useful substances that enable chemists to distinguish aldehydes and ketones from other functional groups.

==Dinitrophenylhydrazones==

Besides just testing for the presence of the carbon-oxygen double bond, the Brady's Reaction can also be used to identify the specific aldehyde or ketone. The precipitate obtained is usually filtered, washed (for example, with methanol) and then recrystallised from a suitable solvent. The solvent used will vary depending on the nature of the carbonyl compound involved. For example, the hydrazones from smaller aldehydes and ketones can be recrystallised from a mixture of ethanol and water.

The 2,4-DNPH derivatives obtained from the reaction of 2,4-DNPH with the various carbonyl compounds have distinct characteristic colours and melting points. There are data tables which show the melting points of the derivatives of common aldehydes and ketones. As such, by finding the melting point of the crystals obtained after recrystallisation, it is possible to identify the carbonyl compound by comparing it with tables of known melting points to find out which carbonyl compound you are likely to have. Some examples of aldehydes and ketones and the melting points of their respective hydrazones are given below.

{| class="wikitable" style="margin: 1em auto 1em auto;text-align:center; background:silver" border="1" cell-padding=5
|- style="background:silver"
| width=200 | ''' Ketone ''' || width=50 | ''' BP/°C ''' || width=200| ''' MP of 2,4-DNP derivative/°C ''' || style="background:silver" | || style="background:silver" | || style="background:silver" | || width=200| '''Aldehyde''' || width=50 | '''BP/°C''' || width=200| '''MP of 2,4-DNP derivative/°C'''
|- style="background:white"
| Acetone (Propanone) || 56 || 128 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Propanal || 48|| 150
|- style="background:white"
| Butanone || 82 || 117 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Butanal || 75 || 123
|- style="background:white"
| 3-pentanone || 102 || 156 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Pentanal || 103 || 98
|- style="background:white"
| Cyclohexanone || 156|| 162 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Hexanal|| 131 || 104
|- style="background:white"
| 1-Phenyl-2-propanone || 216 || 191 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Benzaldehyde|| 179 || 237

|}

=Similar Addition-Elimination Reactions=

[[image: general.png|thumb|left|general equation for addition-elimination reactions involving nitrogen]]

The reaction between 2,4-dinitrophenylhydrazine and carbonyl compounds is actually a very common reaction. It can be observed from the reaction scheme that only the NH2 part of the molecule reacts and the rest remain unchanged. If the NH2 group is attached to other things, similar reactions can also occur via the same mechanism. Some examples of such reactions are shown below. In each reaction, water is lost (condensation process) and a C=N double bond is formed, giving different functional groups in the final products.

=References=
<references />

2,4-Dinitrophenylhydrazine

2007-12-06T13:59:41Z

Seg06:

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|-
! {{chembox header}} | General
|-
| [http://en.wikipedia.org/wiki/IUPAC Systematic name]
| 2,4-Dinitrophenylhydrazine

|-
| Other names
| 2,4-DNPH, Brady's Reagent
|-
| [http://en.wikipedia.org/wiki/Chemical_formula Molecular formula]
| C6H6N4O4
|-
| [http://en.wikipedia.org/wiki/Chemical_file_format SMILES] 
| [H]N([H])N([H])C1=CC=C([N+]
[O-])=O)C=C1[N+]([O-])=O
|-
| [http://en.wikipedia.org/wiki/Molar_mass Molar mass]
| 198.14
|-
| Appearance
| wet, red or orange, crystalline powder
|-
| [http://en.wikipedia.org/wiki/CAS_registry_number CAS number]
| 119-26-6
|-
! {{chembox header}} | Properties
|-
| [http://en.wikipedia.org/wiki/Solubility Solubility in water]
| slight solubility in water
|-
| [http://en.wikipedia.org/wiki/Melting_point Melting point]
| 200-202°C (473-475K) decomposes
|-
! {{chembox header}} | Hazards 
|-
| Main [[Worker safety and health|hazard]]s
| [[image:2,4-dnph-hazard.png|210px|hazard symbols of 2,4-DNPH]]
potential carcinogen
|-
| {{chembox header}} | Except where noted otherwise, data are given for materials in their [[standard state|standard state (at 25 °C, 100 kPa)]] [[wikipedia:Chemical infobox|Infobox disclaimer and references]]
|-
|}

''This article is about the compound 2,4-Dinitrophenylhydrazine, otherwise known as 2,4-DNPH or Brady's Reagent. It is a substituted hydrazine (NH2NH2) and is most commonly used as a qualitative test for the presence of the carbonyl functional group (C=O).''

=Synthesis=

2,4-DNPH can be synthesized via the electrophilic substitution reaction of hydrazine with 2,4-dinitrochlorobenzene. This synthesis was carried out by C. F. H. Allen in 1943<ref>C.F.H Allen, ''Organic Syntheses'', '''1943''', 2, p228.</ref>. The reaction scheme of this reaction is shown below.

[[Image:2,4-dnph-synthesis.png|Synthesis of 2,4-DNPH]]

==Alternative Methods of Synthesis==

Besides using hydrazine, the synthesis of 2,4-dinitrophenylhydrazine has also been carried out using hydrazine hydrate<ref>O.L. Brady;G.V. Elsmie, ''Analyst'', '''1926''', 51, p77</ref> (OH2-H2N-NH2) and hydrazine acetate (NH2NH2)(CH3COOH). On top of that, the 2,4-dinitrochlorobenzene reagent can be replaced with its respective bromine derivative.

=Reaction with Carbonyl Compounds=

2,4-dinitrophenylhydrazine, having a nitrogen atom with lone pairs, is an effective nucleophile. On the other hand, carbonyl compounds, with the polarized carbon-oxygen double bonds, have electrophilic carbon centres. As such, it is no surprise that 2,4-dinitrophenylhydrazine will react readily with carbonyl compounds in a condensation reaction, more specifically known as the Brady's Reaction. The overall reaction scheme and mechanism of this reaction is shown below.

[[Image:2,4-dnph-mechanism.png|550px|Mechanism for Reaction of 2,4-DNPH with carbonyl compounds]]

In chemical experiments, the solid 2,4-DNPH is first dissolved in a methanol/sulphuric acid solvent to give a yellow solution of 2,4-DNPH. This solution is what we call Brady's Reagent. A few drops of carbonyl compound is then added to Brady's Regeant and the reaction will proceed smoothly with no need for heating or any other reagents.

The products obtained from this reaction are water and an organic compound which is known as a dinitrophenylhydrazone. In general, a hydrazone is a class of organic compound which contains the C=N double bond, with the general formula of R2C=NR2. As water is eliminated in the Brady's Reaction, we can see why this reaction is also considered a condensation reaction. In terms of mechanism, this reaction proceeds via a ''nucleophilic addition-elimination'' mechanism. The 2,4-DNPH first adds across the carbon-oxygen double bond to form an intermediate, which then gives the final product upon the elimination of a water molecule.

[[Image:2,4-ppt.jpg|thumb|Positive test of 2,4-DNPH with the carbonyl group (Right) <ref>http://acpcommunity.acp.edu/facultystaff/genchem/GC1/lab/qual/dnp.jpg</ref>]]

==Using the Brady's Reaction==

As mentioned above, 2,4-dinitrophenylhydrazine is mainly used as a positive test for the presence of a carbonyl functional group. The addition of Brady's Reagent to a compound containing the carbonyl functional group will result in the formation of a dinitrophenylhydrazone, which is actually an orange or yellow insoluble solid. As such, with just a simple addition of a few drops of 2,4-DNPH, we are able to tell whether a carbon-oxygen double bond is present, by observing the formation (or absence) of a yellow/orange precipitate. As other functional groups will not react with the hydrazine, Brady's reagent is one of the most useful substances that enable chemists to distinguish aldehydes and ketones from other functional groups.

==Dinitrophenylhydrazones==

Besides just testing for the presence of the carbon-oxygen double bond, the Brady's Reaction can also be used to identify the specific aldehyde or ketone. The precipitate obtained is usually filtered, washed (for example, with methanol) and then recrystallised from a suitable solvent. The solvent used will vary depending on the nature of the carbonyl compound involved. For example, the hydrazones from smaller aldehydes and ketones can be recrystallised from a mixture of ethanol and water.

The 2,4-DNPH derivatives obtained from the reaction of 2,4-DNPH with the various carbonyl compounds have distinct characteristic colours and melting points. There are data tables which show the melting points of the derivatives of common aldehydes and ketones. As such, by finding the melting point of the crystals obtained after recrystallisation, it is possible to identify the carbonyl compound by comparing it with tables of known melting points to find out which carbonyl compound you are likely to have. Some examples of aldehydes and ketones and the melting points of their respective hydrazones are given below.

{| class="wikitable" style="margin: 1em auto 1em auto;text-align:center; background:silver" border="1" cell-padding=5
|- style="background:silver"
| width=200 | ''' Ketone ''' || width=50 | ''' BP/°C ''' || width=200| ''' MP of 2,4-DNP derivative/°C ''' || style="background:silver" | || style="background:silver" | || style="background:silver" | || width=200| '''Aldehyde''' || width=50 | '''BP/°C''' || width=200| '''MP of 2,4-DNP derivative/°C'''
|- style="background:white"
| Acetone (Propanone) || 56 || 128 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Propanal || 48|| 150
|- style="background:white"
| Butanone || 82 || 117 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Butanal || 75 || 123
|- style="background:white"
| 3-pentanone || 102 || 156 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Pentanal || 103 || 98
|- style="background:white"
| Cyclohexanone || 156|| 162 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Hexanal|| 131 || 104
|- style="background:white"
| 1-Phenyl-2-propanone || 216 || 191 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Benzaldehyde|| 179 || 237

|}

=Similar Addition-Elimination Reactions=

[[image: general.png|thumb| general equation for addition-elimination reactions involving nitrogen]]

The reaction between 2,4-dinitrophenylhydrazine and carbonyl compounds is actually a very common reaction. It can be observed from the reaction scheme that only the NH2 part of the molecule reacts and the rest remain unchanged. If the NH2 group is attached to other things, similar reactions can also occur via the same mechanism. Some examples of such reactions are shown below. In each reaction, water is lost (condensation process) and a C=N double bond is formed, giving different functional groups in the final products.

=References=
<references />

File:General.png

2007-12-04T23:41:10Z

Seg06:

2,4-Dinitrophenylhydrazine

2007-12-04T23:27:47Z

Seg06:

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|-
! {{chembox header}} | General
|-
| [http://en.wikipedia.org/wiki/IUPAC Systematic name]
| 2,4-Dinitrophenylhydrazine

|-
| Other names
| 2,4-DNPH, Brady's Reagent
|-
| [http://en.wikipedia.org/wiki/Chemical_formula Molecular formula]
| C6H6N4O4
|-
| [http://en.wikipedia.org/wiki/Chemical_file_format SMILES] 
| [H]N([H])N([H])C1=CC=C([N+]
[O-])=O)C=C1[N+]([O-])=O
|-
| [http://en.wikipedia.org/wiki/Molar_mass Molar mass]
| 198.14
|-
| Appearance
| wet, red or orange, crystalline powder
|-
| [http://en.wikipedia.org/wiki/CAS_registry_number CAS number]
| 119-26-6
|-
! {{chembox header}} | Properties
|-
| [http://en.wikipedia.org/wiki/Solubility Solubility in water]
| slight solubility in water
|-
| [http://en.wikipedia.org/wiki/Melting_point Melting point]
| 200-202°C (473-475K) decomposes
|-
! {{chembox header}} | Hazards 
|-
| Main [[Worker safety and health|hazard]]s
| [[image:2,4-dnph-hazard.png|210px|hazard symbols of 2,4-DNPH]]
potential carcinogen
|-
| {{chembox header}} | Except where noted otherwise, data are given for materials in their [[standard state|standard state (at 25 °C, 100 kPa)]] [[wikipedia:Chemical infobox|Infobox disclaimer and references]]
|-
|}

''This article is about the compound 2,4-Dinitrophenylhydrazine, otherwise known as 2,4-DNPH or Brady's Reagent. It is a substituted hydrazine (NH2NH2) and is most commonly used as a qualitative test for the presence of the carbonyl functional group (C=O).''

=Synthesis=

2,4-DNPH can be synthesized via the electrophilic substitution reaction of hydrazine with 2,4-dinitrochlorobenzene. This synthesis was carried out by C. F. H. Allen in 1943<ref>C.F.H Allen, ''Organic Syntheses'', '''1943''', 2, p228.</ref>. The reaction scheme of this reaction is shown below.

[[Image:2,4-dnph-synthesis.png|Synthesis of 2,4-DNPH]]

==Alternative Methods of Synthesis==

Besides using hydrazine, the synthesis of 2,4-dinitrophenylhydrazine has also been carried out using hydrazine hydrate<ref>O.L. Brady;G.V. Elsmie, ''Analyst'', '''1926''', 51, p77</ref> (OH2-H2N-NH2) and hydrazine acetate (NH2NH2)(CH3COOH). On top of that, the 2,4-dinitrochlorobenzene reagent can be replaced with its respective bromine derivative.

=Reaction with Carbonyl Compounds=

2,4-dinitrophenylhydrazine, having a nitrogen atom with lone pairs, is an effective nucleophile. On the other hand, carbonyl compounds, with the polarized carbon-oxygen double bonds, have electrophilic carbon centres. As such, it is no surprise that 2,4-dinitrophenylhydrazine will react readily with carbonyl compounds in a condensation reaction, more specifically known as the Brady's Reaction. The overall reaction scheme and mechanism of this reaction is shown below.

[[Image:2,4-dnph-mechanism.png|Mechanism for Reaction of 2,4-DNPH with carbonyl compounds]]

In chemical experiments, the solid 2,4-DNPH is first dissolved in a methanol/sulphuric acid solvent to give a yellow solution of 2,4-DNPH. This solution is what we call Brady's Reagent. A few drops of carbonyl compound is then added to Brady's Regeant and the reaction will proceed smoothly with no need for heating or any other reagents.

The products obtained from this reaction are water and an organic compound which is known as a dinitrophenylhydrazone. In general, a hydrazone is a class of organic compound which contains the C=N double bond, with the general formula of R2C=NR2. As water is eliminated in the Brady's Reaction, we can see why this reaction is also considered a condensation reaction. In terms of mechanism, this reaction proceeds via a ''nucleophilic addition-elimination'' mechanism. The 2,4-DNPH first adds across the carbon-oxygen double bond to form an intermediate, which then gives the final product upon the elimination of a water molecule.

[[Image:2,4-ppt.jpg|thumb|Positive test of 2,4-DNPH with the carbonyl group (Right) <ref>http://acpcommunity.acp.edu/facultystaff/genchem/GC1/lab/qual/dnp.jpg</ref>]]

==Using the Brady's Reaction==

As mentioned above, 2,4-dinitrophenylhydrazine is mainly used as a positive test for the presence of a carbonyl functional group. The addition of Brady's Reagent to a compound containing the carbonyl functional group will result in the formation of a dinitrophenylhydrazone, which is actually an orange or yellow insoluble solid. As such, with just a simple addition of a few drops of 2,4-DNPH, we are able to tell whether a carbon-oxygen double bond is present, by observing the formation (or absence) of a yellow/orange precipitate. As other functional groups will not react with the hydrazine, Brady's reagent is one of the most useful substances that enable chemists to distinguish aldehydes and ketones from other functional groups.

==Dinitrophenylhydrazones==

Besides just testing for the presence of the carbon-oxygen double bond, the Brady's Reaction can also be used to identify the specific aldehyde or ketone. The precipitate obtained is usually filtered, washed (for example, with methanol) and then recrystallised from a suitable solvent. The solvent used will vary depending on the nature of the carbonyl compound involved. For example, the hydrazones from smaller aldehydes and ketones can be recrystallised from a mixture of ethanol and water.

The 2,4-DNPH derivatives obtained from the reaction of 2,4-DNPH with the various carbonyl compounds have distinct characteristic colours and melting points. There are data tables which show the melting points of the derivatives of common aldehydes and ketones. As such, by finding the melting point of the crystals obtained after recrystallisation, it is possible to identify the carbonyl compound by comparing it with tables of known melting points to find out which carbonyl compound you are likely to have. Some examples of aldehydes and ketones and the melting points of their respective hydrazones are given below.

{| class="wikitable" style="margin: 1em auto 1em auto;text-align:center; background:silver" border="1" cell-padding=5
|- style="background:silver"
| width=200 | ''' Ketone ''' || width=50 | ''' BP/°C ''' || width=200| ''' MP of 2,4-DNP derivative/°C ''' || style="background:silver" | || style="background:silver" | || style="background:silver" | || width=200| '''Aldehyde''' || width=50 | '''BP/°C''' || width=200| '''MP of 2,4-DNP derivative/°C'''
|- style="background:white"
| Acetone (Propanone) || 56 || 128 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Propanal || 48|| 150
|- style="background:white"
| Butanone || 82 || 117 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Butanal || 75 || 123
|- style="background:white"
| 3-pentanone || 102 || 156 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Pentanal || 103 || 98
|- style="background:white"
| Cyclohexanone || 156|| 162 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Hexanal|| 131 || 104
|- style="background:white"
| 1-Phenyl-2-propanone || 216 || 191 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Benzaldehyde|| 179 || 237

|}

=Similar Addition-Elimination Reactions=

The reaction between 2,4-dinitrophenylhydrazine and carbonyl compounds is actually a very common reaction. It can be observed from the reaction scheme that only the NH2 part of the molecule reacts and the rest remain unchanged. If the NH2 group is attached to other things, similar reactions can also occur via the same mechanism.

[[image: general.png|thumb| general equation for addition-elimination reactions involving nitrogen]]
=References=
<references />

2007-11-29T17:14:34Z

Seg06:

2,4-Dinitrophenylhydrazine

2007-11-29T17:01:49Z

Seg06:

<noinclude>

</noinclude>{| class="toccolours" border="1" style="float: right; clear: right; margin: 0 0 1em 1em; border-collapse: collapse; width: 280px"
! {{chembox header}} | {{PAGENAME}} 
|-
| align="center" colspan="2" bgcolor="#ffffff" | [[Image:2,4-dnph.png|200px|{{PAGENAME}}]] 
|-
! {{chembox header}} | General
|-
| [http://en.wikipedia.org/wiki/IUPAC Systematic name]
| 2,4-Dinitrophenylhydrazine

|-
| Other names
| 2,4-DNPH, Brady's Reagent
|-
| [http://en.wikipedia.org/wiki/Chemical_formula Molecular formula]
| C6H6N4O4
|-
| [http://en.wikipedia.org/wiki/Chemical_file_format SMILES] 
| [H]N([H])N([H])C1=CC=C([N+]
[O-])=O)C=C1[N+]([O-])=O
|-
| [http://en.wikipedia.org/wiki/Molar_mass Molar mass]
| 198.14
|-
| Appearance
| wet, red or orange, crystalline powder
|-
| [http://en.wikipedia.org/wiki/CAS_registry_number CAS number]
| 119-26-6
|-
! {{chembox header}} | Properties
|-
| [http://en.wikipedia.org/wiki/Solubility Solubility in water]
| slight solubility in water
|-
| [http://en.wikipedia.org/wiki/Melting_point Melting point]
| 200-202°C (473-475K) decomposes
|-
! {{chembox header}} | Hazards 
|-
| Main [[Worker safety and health|hazard]]s
| [[image:2,4-dnph-hazard.png|210px|hazard symbols of 2,4-DNPH]]
potential carcinogen
|-
| {{chembox header}} | Except where noted otherwise, data are given for materials in their [[standard state|standard state (at 25 °C, 100 kPa)]] [[wikipedia:Chemical infobox|Infobox disclaimer and references]]
|-
|}

''This article is about the compound 2,4-Dinitrophenylhydrazine, otherwise known as 2,4-DNPH or Brady's Reagent. It is a substituted hydrazine (NH2NH2) and is most commonly used as a qualitative test for the presence of the carbonyl functional group (C=O).''

=Synthesis=

2,4-DNPH can be synthesized via the electrophilic substitution reaction of hydrazine with 2,4-dinitrochlorobenzene. This synthesis was carried out by C. F. H. Allen in 1943<ref>C.F.H Allen, ''Organic Syntheses'', '''1943''', 2, p228.</ref>. The reaction scheme and mechanism of this reaction is shown below.

[[Image:2,4-dnph-synthesis.png|Synthesis of 2,4-DNPH]]

==Alternative Methods of Synthesis==

Besides using hydrazine, the synthesis of 2,4-dinitrophenylhydrazine has also been carried out using hydrazine hydrate<ref>O.L. Brady;G.V. Elsmie, ''Analyst'', '''1926''', 51, p77</ref> (OH2-H2N-NH2) and hydrazine acetate (NH2NH2)(CH3COOH). On top of that, the 2,4-dinitrochlorobenzene reagent can be replaced with its respective bromine derivative.

=Reaction with Carbonyl Compounds=

2,4-dinitrophenylhydrazine, having a nitrogen atom with lone pairs, is an effective nucleophile. On the other hand, carbonyl compounds, with the polarized carbon-oxygen double bonds, have electrophilic carbon centres. As such, it is no surprise that 2,4-dinitrophenylhydrazine will react readily with carbonyl compounds in a condensation reaction, more specifically known as the Brady's Reaction. The overall reaction scheme and mechanism of this reaction is shown below.

[[Image:2,4-dnph-mechanism.png|Mechanism for Reaction of 2,4-DNPH with carbonyl compounds]]

In chemical experiments, the solid 2,4-DNPH is first dissolved in a methanol/sulphuric acid solvent to give a yellow solution of 2,4-DNPH. This solution is what we call Brady's Reagent. A few drops of carbonyl compound is then added to Brady's Regeant and the reaction will proceed smoothly with no need for heating or any other reagents.

The products obtained from this reaction are water and an organic compound which is known as a dinitrophenylhydrazone. In general, a hydrazone is a class of organic compound which contains the C=N double bond, with the general formula of R2C=NR2. As water is eliminated in the Brady's Reaction, we can see why this reaction is also considered a condensation reaction. In terms of mechanism, this reaction proceeds via a ''nucleophilic addition-elimination'' mechanism. The 2,4-DNPH first adds across the carbon-oxygen double bond to form an intermediate, which then gives the final product upon the elimination of a water molecule.

[[Image:2,4-ppt.jpg|thumb|Positive test of 2,4-DNPH with the carbonyl group (Right) <ref>http://acpcommunity.acp.edu/facultystaff/genchem/GC1/lab/qual/dnp.jpg</ref>]]

==Using the Brady's Reaction==

As mentioned above, 2,4-dinitrophenylhydrazine is mainly used as a positive test for the presence of a carbonyl functional group. The addition of Brady's Reagent to a compound containing the carbonyl functional group will result in the formation of a hydrazone, which is actually an orange or yellow precipitate. As such, with just a simple addition of a few drops of 2,4-DNPH, we are able to tell whether a carbon-oxygen double bond is present, by observing the formation (or absence) of a precipitate. As other functional groups will not react with the hydrazine, Brady's reagent is one of the most useful substances that enable chemists to distinguish aldehydes and ketones from other functional groups.

==Dinitrophenylhydrazones==

The 2,4-DNPH derivatives obtained from the reaction of 2,4-DNPH with the various carbonyl compounds have distinct characteristic colours and boiling points. As such, it is possible to identify the carbonyl compound given the hydrazone product. Some examples of aldehydes and ketones and the boiling points of their respective hydrazones are given below.

{| class="wikitable" style="margin: 1em auto 1em auto;text-align:center; background:silver" border="1" cell-padding=5
|- style="background:silver"
| width=200 | ''' Ketone ''' || width=50 | ''' BP/°C ''' || width=200| ''' MP of 2,4-DNP derivative/°C ''' || style="background:silver" | || style="background:silver" | || style="background:silver" | || width=200| '''Aldehyde''' || width=50 | '''BP/°C''' || width=200| '''MP of 2,4-DNP derivative/°C'''
|- style="background:white"
| Acetone (Propanone) || 56 || 128 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Propanal || 48|| 150
|- style="background:white"
| Butanone || 82 || 117 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Butanal || 75 || 123
|- style="background:white"
| 3-pentanone || 102 || 156 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Pentanal || 103 || 98
|- style="background:white"
| Cyclohexanone || 156|| 162 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Hexanal|| 131 || 104
|- style="background:white"
| 1-Phenyl-2-propanone || 216 || 191 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Benzaldehyde|| 179 || 237

|}

=Interesting Facts=

=References=
<references />

2007-11-29T15:00:13Z

Seg06:

2,4-Dinitrophenylhydrazine

2007-11-29T14:56:15Z

Seg06:

<noinclude>

</noinclude>{| class="toccolours" border="1" style="float: right; clear: right; margin: 0 0 1em 1em; border-collapse: collapse; width: 280px"
! {{chembox header}} | {{PAGENAME}} 
|-
| align="center" colspan="2" bgcolor="#ffffff" | [[Image:2,4-dnph.png|200px|{{PAGENAME}}]] 
|-
! {{chembox header}} | General
|-
| [http://en.wikipedia.org/wiki/IUPAC Systematic name]
| 2,4-Dinitrophenylhydrazine

|-
| Other names
| 2,4-DNPH, Brady's Reagent
|-
| [http://en.wikipedia.org/wiki/Chemical_formula Molecular formula]
| C6H6N4O4
|-
| [http://en.wikipedia.org/wiki/Chemical_file_format SMILES] 
| [H]N([H])N([H])C1=CC=C([N+]
[O-])=O)C=C1[N+]([O-])=O
|-
| [http://en.wikipedia.org/wiki/Molar_mass Molar mass]
| 198.14
|-
| Appearance
| wet, red or orange, crystalline powder
|-
| [http://en.wikipedia.org/wiki/CAS_registry_number CAS number]
| 119-26-6
|-
! {{chembox header}} | Properties
|-
| [http://en.wikipedia.org/wiki/Solubility Solubility in water]
| {{{Sol_Water}}} g/100 ml (25°C) 
|-



| [http://en.wikipedia.org/wiki/Melting_point Melting point]
| 200-202°C (473-475K) decomposes
|-
! {{chembox header}} | Hazards 
|-
| [[Material safety data sheet|MSDS]]
| [[{{PAGENAME}} (data page)#Material Safety Data Sheet|External MSDS]] 
|-
| Main [[Worker safety and health|hazard]]s
| [[image:2,4-dnph-hazard.png|210px|hazard symbols of 2,4-DNPH]] 
|-
| [[NFPA 704]]
| {{{NFPA}}}
|-
| [[Risk and Safety Statements|R/S statement]]
| [[List of R-phrases|R]]: {{{R-S}}} [[List of S-phrases|S]]: ?
|-
| [[RTECS]] number
| {{{RTECS}}}
|-
! {{chembox header}} | [[{{PAGENAME}} (data page)|Supplementary data page]]
|-
| [[{{PAGENAME}} (data page)#Structure and properties|Structure and properties]]
| [http://en.wikipedia.org/wiki/Refractive_index ''n''], [http://en.wikipedia.org/wiki/Dielectric_constant εr], etc.
|-
| [[{{PAGENAME}} (data page)#Thermodynamic properties|Thermodynamic data]]
| Phase behaviour Solid, liquid, gas
|-
| [[{{PAGENAME}} (data page)#Spectral data|Spectral data]]
| [[UV/VIS spectroscopy|UV]], [[Infrared spectroscopy|IR]], [[nuclear magnetic resonance spectroscopy|NMR]], [[Mass spectrometry|MS]]

|-
| {{chembox header}} | Except where noted otherwise, data are given for materials in their [[standard state|standard state (at 25 °C, 100 kPa)]] [[wikipedia:Chemical infobox|Infobox disclaimer and references]]
|-
|}

''This article is about the compound 2,4-Dinitrophenylhydrazine, otherwise known as 2,4-DNPH or Brady's Reagent. It is a substituted hydrazine (NH2NH2) and is most commonly used as a qualitative test for the presence of the carbonyl functional group (C=O).''

=Synthesis=

2,4-DNPH can be synthesized via the electrophilic substitution reaction of hydrazine with 2,4-Dinitrochlorobenzene. This synthesis was carried out by C. F. H. Allen in 1943<ref>C.F.H Allen, ''Organic Syntheses'', '''1943''', 2, p228.</ref>. The reaction scheme and mechanism of this reaction is shown below.

[[Image:2,4-dnph-synthesis.png|Synthesis of 2,4-DNPH]]

==Alternative Methods of Synthesis==

Besides using hydrazine, the synthesis of 2,4-dinitrophenylhydrazine has also been carried out using hydrazine hydrate<ref>O.L. Brady;G.V. Elsmie, ''Analyst'', '''1926''', 51, p77</ref> (OH2-H2N-NH2) and hydrazine acetate (NH2NH2)(CH3COOH). On top of that, the 2,4-dinitrochlorobenzene reagent can be replaced with its respective bromine derivative.

=Reaction with Carbonyl Compounds=

As mentioned, 2,4-dinitrophenylhydrazine is mainly used as a positive test for the carbonyl group. In chemical experiments, the solid 2,4-DNPH is first dissolved in a methanol/sulphuric acid solvent to give a yellow solution of 2,4-DNPH. This solution is what we call Brady's Reagent. The addition of Brady's Reagent to a compound containing the carbonyl functional group will result in the formation of an orange or red precipitate. Other functional groups will not react with the hydrazine. As such, 2,4-DNPH is one of the most useful compounds that enable chemists to distinguish aldehydes and ketones from other functional groups.

[[Image:2,4-dnph-mechanism.png|Mechanism for Reaction of 2,4-DNPH with carbonyl compounds]]

The products obtained from this reaction are water and an organic compound which is known as a dinitrophenylhydrazone. In general, a hydrazone is a class of organic compound which contains the C=N double bond, with the general formula of R2C=NR2. As water is eliminated in the Brady's Reaction, we can see that this reaction is a simple condensation process.

==Dinitrophenylhydrazones==

The 2,4-DNPH derivatives obtained from the reaction of 2,4-DNPH with the various carbonyl compounds have distinct characteristic colours and boiling points. As such, it is possible to identify the carbonyl compound given the hydrazone product. Some examples of aldehydes and ketones and the boiling points of their respective hydrazones are given below.

{| class="wikitable" style="margin: 1em auto 1em auto;text-align:center; background:silver" border="1" cell-padding=5
|- style="background:silver"
| width=200 | ''' Ketone ''' || width=50 | ''' BP/°C ''' || width=200| ''' MP of 2,4-DNP derivative/°C ''' || style="background:silver" | || style="background:silver" | || style="background:silver" | || width=200| '''Aldehyde''' || width=50 | '''BP/°C''' || width=200| '''MP of 2,4-DNP derivative/°C'''
|- style="background:white"
| Acetone (Propanone) || 56 || 128 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Propanal || 48|| 150
|- style="background:white"
| Butanone || 82 || 117 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Butanal || 75 || 123
|- style="background:white"
| 3-pentanone || 102 || 156 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Pentanal || 103 || 98
|- style="background:white"
| Cyclohexanone || 156|| 162 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Hexanal|| 131 || 104
|- style="background:white"
| 1-Phenyl-2-propanone || 216 || 191 || style="background:silver"| || style="background:silver"| || style="background:silver"| || Benzaldehyde|| 179 || 237

|}

=Interesting Facts=

=References=
<references />

2007-11-29T00:11:15Z

Seg06:

2,4-Dinitrophenylhydrazine

2007-11-28T23:53:57Z

Seg06:

<noinclude>

</noinclude>{| class="toccolours" border="1" style="float: right; clear: right; margin: 0 0 1em 1em; border-collapse: collapse; width: 280px"
! {{chembox header}} | {{PAGENAME}} 
|-
| align="center" colspan="2" bgcolor="#ffffff" | [[Image:2,4-dnph.png|200px|{{PAGENAME}}]] 
|-
! {{chembox header}} | General
|-
| [http://en.wikipedia.org/wiki/IUPAC Systematic name]
| 2,4-Dinitrophenylhydrazine

|-
| Other names
| 2,4-DNPH, Brady's Reagent
|-
| [http://en.wikipedia.org/wiki/Chemical_formula Molecular formula]
| C6H6N4O4
|-
| [http://en.wikipedia.org/wiki/Chemical_file_format SMILES] 
| [H]N([H])N([H])C1=CC=C([N+]
[O-])=O)C=C1[N+]([O-])=O
|-
| [http://en.wikipedia.org/wiki/Molar_mass Molar mass]
| {{{MolarMass}}}
|-
| Appearance
| wet, red or orange, crystalline powder
|-
| [http://en.wikipedia.org/wiki/CAS_registry_number CAS number]
| 119-26-6
|-
! {{chembox header}} | Properties
|-
| [http://en.wikipedia.org/wiki/Density Density] & [http://en.wikipedia.org/wiki/Phase_%28matter%29 phase]
| {{{Density}}} g/cm³ 
|-
| [http://en.wikipedia.org/wiki/Solubility Solubility in water]
| {{{Sol_Water}}} g/100 ml (25°C) 
|-



| [http://en.wikipedia.org/wiki/Melting_point Melting point]
| {{{Mp}}} K 
|-
| [http://en.wikipedia.org/wiki/Boiling_point Boiling point]
| {{{Bp}}} K
|-
| [http://en.wikipedia.org/wiki/Specific_rotation Chiral rotation <nowiki>[α]</nowiki>D] 
| {{{Rotation}}}°
|-
| [http://en.wikipedia.org/wiki/Viscosity Viscosity]
| {{{Viscosity}}} [[Poise|cP]] at 25°C 
|-
! {{chembox header}} | Structure
|-
| [http://en.wikipedia.org/wiki/Orbital_hybridisation Molecular shape] 
| {{{Mol_Shape}}} 
|-
| [http://en.wikipedia.org/wiki/Coordination_geometry Coordination geometry] 
| {{{Coordination}}} 
|-
| [http://en.wikipedia.org/wiki/Crystal_structure Crystal structure] 
| {{{Crystal_Structure}}} 
|-
| [[Dipole#Molecular_dipoles|Dipole moment]]
| {{{DM}}} [[Debye|D]]
|-
! {{chembox header}} | Hazards 
|-
| [[Material safety data sheet|MSDS]]
| [[{{PAGENAME}} (data page)#Material Safety Data Sheet|External MSDS]] 
|-
| Main [[Worker safety and health|hazard]]s
| {{{Hazards}}} 
|-
| [[NFPA 704]]
| {{{NFPA}}}
|-
| [[Flash point]]
| {{{Fp}}}°C
|-
| [[Risk and Safety Statements|R/S statement]]
| [[List of R-phrases|R]]: {{{R-S}}} [[List of S-phrases|S]]: ?
|-
| [[RTECS]] number
| {{{RTECS}}}
|-
! {{chembox header}} | [[{{PAGENAME}} (data page)|Supplementary data page]]
|-
| [[{{PAGENAME}} (data page)#Structure and properties|Structure and properties]]
| [http://en.wikipedia.org/wiki/Refractive_index ''n''], [http://en.wikipedia.org/wiki/Dielectric_constant εr], etc.
|-
| [[{{PAGENAME}} (data page)#Thermodynamic properties|Thermodynamic data]]
| Phase behaviour Solid, liquid, gas
|-
| [[{{PAGENAME}} (data page)#Spectral data|Spectral data]]
| [[UV/VIS spectroscopy|UV]], [[Infrared spectroscopy|IR]], [[nuclear magnetic resonance spectroscopy|NMR]], [[Mass spectrometry|MS]]

|-
| {{chembox header}} | Except where noted otherwise, data are given for materials in their [[standard state|standard state (at 25 °C, 100 kPa)]] [[wikipedia:Chemical infobox|Infobox disclaimer and references]]
|-
|}

''This article is about the compound 2,4-Dinitrophenylhydrazine, otherwise known as 2,4-DNPH or Brady's Reagent. It is a substituted hydrazine (H2NNH2) and is most commonly used as a qualitative test for the presence of the carbonyl functional group (C=O).''

=Synthesis=

2,4-DNPH can be synthesized via the electrophilic substitution reaction of hydrazine with 2,4-Dinitrochlorobenzene. This synthesis was carried out by C. F. H. Allen in 1943<ref>C.F.H Allen, ''Organic Syntheses'', '''1943''', 2, p228.</ref>. The reaction scheme and mechanism of this reaction is shown below.

[[Image:2,4-dnph-synthesis.png|Synthesis of 2,4-DNPH]]

==Alternative Methods of Synthesis==

Besides using hydrazine, the synthesis of 2,4-dinitrophenylhydrazine has also been carried out using hydrazine hydrate<ref>O.L. Brady;G.V. Elsmie, ''Analyst'', '''1926''', 51, p77</ref> (OH2-H2N-NH2) and hydrazine acetate (NH2NH2)(CH3COOH). On top of that, the 2,4-dinitrochlorobenzene reagent can be replaced with its respective bromine derivative.

=Reaction with Carbonyl Compounds=

As mentioned, 2,4-dinitrophenylhydrazine is mainly used as a positive test for the carbonyl group. In chemical experiments, the solid 2,4-DNPH is first dissolved in a methanol/sulphuric acid solvent to give a yellow solution of 2,4-DNPH. This solution is what we call Brady's Reagent. The addition of Brady's Reagent to a compound containing the carbonyl functional group will result in the formation of an orange or red precipitate. Other functional groups will not react with the hydrazine. As such, 2,4-DNPH is one of the most useful compounds that enable chemists to distinguish aldehydes and ketones from other functional groups.

The products obtained from this reaction are water and an organic compound which is known as a dinitrophenylhydrazone. In general, a hydrazone is a class of organic compound which contains the C=N double bond, with the general formula of R2C=NR2. As water is eliminated in the Brady's Reaction, we can see that this reaction is a simple condensation process.

==Dinitrophenylhydrazones==

The 2,4-DNPH derivatives obtained from the reaction of 2,4-DNPH with the various carbonyl compounds have distinct characteristic colours and boiling points. As such, it is possible to identify the carbonyl compound given the hydrazone product. Some examples of aldehydes and ketones and the boiling points of their respective hydrazones are given below.

=Interesting Facts=

=References=
<references />

2,4-Dinitrophenylhydrazine

2007-11-28T23:36:27Z

2,4-Dinitrophenylhydrazine

2007-11-27T23:25:20Z

Seg06: New page: ''This article is about the compound 2,4-Dinitrophenylhydrazine, otherwise known as 2,4-DNPH or Brady's Reagent. It is a substituted hydrazine (H2N=NH2) and is most commonly used as a qual...

''This article is about the compound 2,4-Dinitrophenylhydrazine, otherwise known as 2,4-DNPH or Brady's Reagent. It is a substituted hydrazine (H2N=NH2) and is most commonly used as a qualitative test for the presence of the carbonyl functional group (C=O).''

=Synthesis=

2,4-DNPH can be synthesized via the electrophilic substitution reaction of hydrazine with 2,4-Dinitrochlorobenzene. This synthesis was carried out by . The reaction scheme and mechanism of this reaction is shown below.

=Reaction with Carbonyl Compounds=

The products obtained from this reaction are water and a hydrazone. A hydrazone is a class of organic compound which contains the C=N double bond, with the general formula of R2C=NR2. As water is eliminated in the Brady's Reaction, we can see that this reaction is a simple condensation process.

The 2,4-DNPH derivatives obtained from the reaction of 2,4-DNPH with the various carbonyl compounds have distinct characteristic colours and boiling points. As such, it is possible to identify the carbonyl compound given the hydrazone product. Some examples of aldehydes and ketones and the boiling points of their respective hydrazones are given below.

=Interesting Facts=