DCMU
{{hatnote group|
{{Distinguish|text = the mercurial diuretic Diurone}}
{{for|the DC comics Movie Universe|DC Extended Universe}}
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{{chembox
| ImageFile = Diuron.svg
| ImageAlt = Skeletal formula of DCMU
| ImageFile1 = DCMU-3D-balls.png
| ImageAlt1 = Ball-and-stick model of the DCMU molecule
| PIN = N′-(3,4-Dichlorophenyl)-N,N-dimethylurea
| OtherNames = 3-(3,4-Dichlorophenyl)-1,1-dimethylurea, Karmex, Diuron, Direx
| Section1 = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 3008
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 116509
| SMILES = Clc1ccc(NC(=O)N(C)C)cc1Cl
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 278489
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C9H10Cl2N2O/c1-13(2)9(14)12-6-3-4-7(10)8(11)5-6/h3-5H,1-2H3,(H,12,14)
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = XMTQQYYKAHVGBJ-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 330-54-1
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = C18428
| PubChem = 3120
| EC_number = 206-354-4
| RTECS = YS8925000
| UNNumber = 3077, 2767
| UNII = 9I3SDS92WY
}}
| Section2 = {{Chembox Properties
| C=9|H=10|Cl=2|N=2|O=1
| Density = 1.48 g/cm3
| MeltingPtC = 158
| BoilingPtC = 180
| Solubility = 42 mg/L
| Appearance = white crystalline solid
| VaporPressure = 0.000000002 mmHg (20°C)
}}
| Section7 = {{Chembox Hazards
| PEL = none{{PGCH|0247}}
| FlashPt = noncombustible
| GHSPictograms = {{GHS07}}{{GHS08}}{{GHS09}}
| GHSSignalWord = Warning
| HPhrases = {{H-phrases|302|351|373|410}}
| PPhrases = {{P-phrases|201|202|260|264|270|273|281|301+312|308+313|314|330|391|405|501}}
}}
}}
DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea) is an algicide and herbicide of the aryl urea class that inhibits photosynthesis. It was introduced by Bayer in 1954 under the trade name of Diuron.
History
In 1952, chemists at E. I. du Pont de Nemours and Company patented a series of aryl urea derivatives as herbicides. Several compounds covered by this patent were commercialized as herbicides: chlortoluron (3-chloro-4-methylphenyl) and DCMU, the (3,4-dichlorophenyl) example.{{cite patent |country=US |number=2655445 |status=patent |gdate=1953-10-13 |fdate=1952-02-14 |pridate=1949-12-06 |invent1 =Todd C.W. |title=3-(Halophenyl)-1-methyl-1-(methyl or ethyl) ureas and herbicidal compositions and methods employing same |assign1=E. I. du Pont de Nemours & Co.}}{{cite book |doi=10.1016/B978-0-12-374367-1.00080-X |chapter=Phenylurea Herbicides |title=Hayes' Handbook of Pesticide Toxicology |year=2010 |last1=Liu |first1=Jing |pages=1725–1731 |isbn=9780123743671 }} Subsequently, over thirty related urea analogs with the same mechanism of action reached the market worldwide.{{cite web |url=http://www.alanwood.net/pesticides/class_herbicides.html#urea_herbicides |title=Urea herbicides |website=alanwood.net|access-date=2021-03-26}}
Synthesis
As described in the du Pont patent, the starting material is 3,4-dichloroaniline, which is treated with phosgene to form a isocyanate derivative. This is subsequently reacted with dimethylamine to give the final product.
:Aryl-NH2 + COCl2 → Aryl-NCO
:Aryl-NCO + NH(CH3)2 → Aryl-NHCON(CH3)2
Mechanism of action
DCMU is a very specific and sensitive inhibitor of photosynthesis. It blocks the QB plastoquinone binding site of photosystem II, disallowing the electron flow from photosystem II to plastoquinone.{{Cite journal | doi = 10.1016/0014-5793(86)80911-5 | title = Evidence for a dual function of the herbicide-binding D1 protein in photosystem II | year = 1986 | last1 = Metz | first1 = J | last2 = Pakrasi | first2 = H | last3 = Seibert | first3 = M | last4 = Arntzer | first4 = C | journal = FEBS Letters | volume = 205 | issue = 2 | pages = 269| s2cid = 84205263 | doi-access = free }} This interrupts the photosynthetic electron transport chain in photosynthesis and thus reduces the ability of the plant to turn light energy into chemical energy (ATP and reductant potential).
DCMU only blocks electron flow from photosystem II, it has no effect on photosystem I or other reactions in photosynthesis, such as light absorption or carbon fixation in the Calvin cycle.{{Citation needed|reason=reliable source needed for the whole sentence|date=April 2014}}
However, because it blocks electrons produced from water oxidation in PS II from entering the plastoquinone pool, "linear" photosynthesis is effectively shut down, as there are no available electrons to exit the photosynthetic electron flow cycle for reduction of NADP+ to NADPH.
In fact, it was found that DCMU not only does not inhibit the cyclic photosynthetic pathway, but, under certain circumstances, actually stimulates it.HUBER, S.C. EDWARDS, G.E. (1976), Studies on the Pathway of Cyclic Electron Flow in Mesophyll Chloroplasts of a C4 Plant, Biochimica et Biophysica Acta (BBA) - Bioenergetics, Volume 449, Issue 3, 6 December 1976, Pages 420-433, {{doi|10.1016/0005-2728(76)90153-5}}{{cite journal | pmc = 1056483 | pmid=16665372 | volume=83 | issue=4 | title=Regulation of Cyclic Photophosphorylation during Ferredoxin-Mediated Electron Transport : Effect of DCMU and the NADPH/NADP Ratio |date=April 1987 | journal=Plant Physiol. | pages=965–9 | doi=10.1104/pp.83.4.965| last1=Hosler | first1=J. P. | last2=Yocum | first2=C. F. }}
Because of these effects, DCMU is often used to study energy flow in photosynthesis.
Toxicity
DCMU (Diuron) has been characterized as a known/likely human carcinogen based on animal testing.{{cite web |title=Diuron |url=https://pubchem.ncbi.nlm.nih.gov/source/hsdb/382 |website=National Center for Biotechnology Information |publisher=United States National Library of Medicine |number=382 |access-date=9 November 2021}}{{cite tech report |type=Memorandum |first1=Taylor |last1=Linda |first2=Rinde |last2=Esther |title=Carcinogenicity Peer Review of Diuron |number=20460 |institution=United States Environmental Protection Agency |date=1997-05-08 |url=https://www3.epa.gov/pesticides/chem_search/cleared_reviews/csr_PC-035505_8-May-97_042.pdf |format=PDF |place=Washington, D.C.}}
References
{{Reflist}}
{{Herbicides}}
{{phenylurea herbicides}}
Category:Chlorobenzene derivatives