查看“︁乙酸酐”︁的源代码

{{Chembox
| Name = 乙酸酐
| ImageFileL1 = Acetic anhydride2DACS.svg
| ImageNameL2 = Acetic anhydride
| ImageFileR1 = Acetic-anhydride-3D-vdW.png
| ImageNameR1 = Acetic anhydride
|  ImageFile2 = Acetic_anhydride_liquid.jpg
|  ImageSize2 = 150px
|  ImageName2 = 乙酸酐的样品，它是无色液体
| IUPACName = acetic anhydride
| OtherNames = 醋酸酐，乙酐，醋酐，無水醋酸
|Section1={{Chembox Identifiers
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 36610
| SMILES = O=C(OC(=O)C)C
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 2E48G1QI9Q
| InChIKey = WFDIJRYMOXRFFG-UHFFFAOYAH
| SMILES1 = CC(=O)OC(=O)C
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C4H6O3/c1-3(5)7-4(2)6/h1-2H3
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = WFDIJRYMOXRFFG-UHFFFAOYSA-N
| CASNo = 108-24-7
| CASNo_Ref = {{cascite|correct|CAS}}
| PubChem = 7918
| EINECS = 203-564-8
| RTECS = AK1925000
| InChI = 1/C4H6O3/c1-3(5)7-4(2)6/h1-2H3
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 7630
 }}
|Section2 = {{Chembox Properties
| Formula = C<sub>4</sub>H<sub>6</sub>O<sub>3</sub>
| MolarMass = 102.09
| Appearance = 无色澄清液体
| Density = 1.08 g/cm<sup>3</sup> (液態)
| Solubility = 反应
| MeltingPt = −73.1&nbsp;°C
| BoilingPt = 139.8&nbsp;°C
  }}
| Section3 = {{Chembox Structure
| Dipole =
  }}
| Section7 = {{Chembox Hazards
| ExternalMSDS =
| wxxfh={{wxxfh|C}}
| RPhrases = {{R10}}, {{R20/22}}, {{R34}}
| SPhrases = {{S1/2}}, {{S26}}, {{S36/37/39}}, {{S45}}
| FlashPt = 54&nbsp;°C
  }}
| Section8 = {{Chembox Related
| Function = [[酸酐]]
| OtherFunctn = [[丙酸酐]]
| OtherCpds = [[乙酸]]<br />[[乙酰氯]]
  }}
}}

'''乙酸酐'''是由[[乙酸]]衍生出来的[[酸酐]]，分子式为{{化學式|{{官能基|碳|氫|3|碳|氧|link=}}|2|氧}}，常缩写为[[乙酰基|Ac]]<sub>2</sub>O。在[[有机合成]]中常用它作[[乙酰化]]试剂或失水剂。在室温下乙酸酐为无色液体，与空气中的[[水分子|水分]]反应，从而散发出乙酸的强烈味道。

== 生产 ==

乙酸酐可由[[乙酸甲酯]]的[[孟山都法]][[一氧化碳|羰基化]]制得，常以[[铑]]和[[锂]]的[[碘化物]]作催化剂：<ref>Zoeller, J. R.; Agreda, V. H.; Cook, S. L.; Lafferty, N. L.; Polichnowski, S. W.; Pond, D. M.  "Eastman Chemical Company Acetic Anhydride Process" Catalysis Today (1992), volume 13, pp.73-91. doi:10.1016/0920-5861(92)80188-S</ref>

: <math>\mathrm{CH}_3\mathrm{CO}_2\mathrm{CH}_3 + \mathrm{CO} \rightarrow \left( \mathrm{CH}_3\mathrm{CO}\right)_2\mathrm{O}</math>

该反应中，乙酸甲酯先被转化为[[碘甲烷]]和一个乙酸盐。然后碘甲烷的羰基化得到[[乙酰碘]]，和乙酸盐或乙酸反应生成产物。由于乙酸酐在水中不稳定，该反应需在无水环境中进行。相比之下，孟山都乙酸合成法虽然也涉及含铑催化剂催化羰基化碘甲烷，但起码有部分反应是在水溶液中的。

1922年，随着由乙酸酐合成的[[醋酸纤维]]需求量大大增加，瓦克（Wacker Chemie）发明了一种新的制取乙酸酐的方法，即以[[乙烯酮]]和乙酸反应来制取。该反应中的乙烯酮可由乙酸高温失水获得。<!-- [http://books.google.com/books?id=36kHHvzx6M8C&pg=PA200&lpg=PA200&dq=wacker+verfahren+essigs%C3%A4ureanhydrid&source=web&ots=n4is04tlMR&sig=NZFcsmFpA1p6p0PBp0zNzAWmFo4#PPA201,M1], [http://www.wacker.com/cms/en/wacker_group/wacker_facts/history/history.jsp] -->

乙酸酐价格很便宜，在实验室中通常不需制取，直接购买使用。

== 用途 ==

Ac<sub>2</sub>O主要用来[[乙酰化]]纤维素制取[[醋酸纤维]]，应用在胶片和其他领域中。

一般[[醇]]类和[[胺]]类可被乙酰化。<ref>{{cite web | title=Science is Fun… | work=Chemical of the Week | url=http://scifun.chem.wisc.edu/CHEMWEEK/AceticAcid/AceticAcid.html | accessdate=2006-03-25 | deadurl=yes | archiveurl=https://web.archive.org/web/20060303081507/http://scifun.chem.wisc.edu/chemweek/AceticAcid/AceticAcid.html | archivedate=2006-03-03 | df= }}</ref>
例如乙酸酐与[[乙醇]]的反应为：

: (CH<sub>3</sub>CO)<sub>2</sub>O  +  CH<sub>3</sub>CH<sub>2</sub>OH → [[乙酸乙酯|CH<sub>3</sub>CO<sub>2</sub>CH<sub>2</sub>CH<sub>3</sub>]]  +  CH<sub>3</sub>CO<sub>2</sub>H

通常以碱，如[[吡啶]]作为催化剂。具有[[路易斯酸]]性的[[钪]]盐也可作为催化剂。<ref>Macor, J.; Sampognaro, A. J.; Verhoest, P. R.; Mack, R. A. "(R)-(+)-2-Hydroxy-1,2,2-Triphenylethyl Acetate" Organic Syntheses, Collected Volume 10, p.464 (2004). {{cite web |url=http://www.orgsyn.org/orgsyn/pdfs/V77P0045.pdf |title=存档副本 |accessdate=2008-04-23 |deadurl=yes |archiveurl=https://web.archive.org/web/20080910083951/http://www.orgsyn.org/orgsyn/pdfs/V77P0045.pdf |archivedate=2008-09-10 }}</ref>

[[阿司匹林]]（乙酰水杨酸），是用乙酸酐对[[水杨酸]]乙酰化来制取的。乙酸酐与[[吗啡]]反应可用于合成[[海洛因]]，因此它被[[美国缉毒局]]列为第二类易制毒化学品，[[中华人民共和国刑法|《中华人民共和国刑法》]]第350条也将其列为违禁。

: <math>\rm (CH_3CO)_2O + C_{17}H_{19}NO_3 {=\!=\!=\!=} C_{21}H_{23}NO_5 + H_2O </math>

== 水解 ==

乙酸酐在水中的溶解度大约是2.6%（以质量）。<ref>{{cite web |title=British Petroleum |work=Acetic Anhydride: Frequently Asked Questions (PDF) |url=http://www.bp.com/liveassets/bp_internet/globalbp/STAGING/global_assets/downloads/pdfs/acetyls_aromatics_pta/AceticAnhydrideFAQ.pdf |accessdate=2006-05-03 |deadurl=yes |archiveurl=https://web.archive.org/web/20071011104749/http://www.bp.com/liveassets/bp_internet/globalbp/STAGING/global_assets/downloads/pdfs/acetyls_aromatics_pta/AceticAnhydrideFAQ.pdf |archivedate=2007-10-11 }}</ref>但是和其他酸酐一样，其水溶液不稳定，容易发生[[水解反应]]生成乙酸：<ref>{{cite web |title=Celanese |work=Acetic Anhydride: Material Safety Data Sheet (PDF) |url=http://www.celanese.com/msds/pdf/570-22027587.pdf |accessdate=2006-05-03 |deadurl=yes |archiveurl=https://web.archive.org/web/20070927025258/http://www.celanese.com/msds/pdf/570-22027587.pdf |archivedate=2007-09-27 }}</ref>

: <math>\left( \mathrm{CH}_3\mathrm{CO}\right)_2\mathrm{O} + \mathrm{H}_2\mathrm{O} \rightarrow 2\mathrm{CH}_3\mathrm{COOH}</math>

== 安全 ==

乙酸酐具有刺激性而且可燃。由于它可与水反应，灭火时常选用二氧化碳或醇泡沫。<ref>{{cite web | title=Data Sheets | work=International Occupational Safety and Health Information Centre | url=http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc02/icsc0209.htm | accessdate=2006-04-13 | archive-date=2006-09-04 | archive-url=https://web.archive.org/web/20060904222415/http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc02/icsc0209.htm | dead-url=no }}</ref>乙酸酐蒸汽对人有害。<ref>{{cite web | title=NIOSH | work=Pocket Guide to Chemical Hazards | url=http://www.cdc.gov/niosh/npg/npgd0003.html | accessdate=2006-04-13 | archive-date=2006-04-22 | archive-url=https://web.archive.org/web/20060422144317/http://www.cdc.gov/niosh/npg/npgd0003.html | dead-url=no }}</ref>

== 参考资料 ==

<div class="references-small">
<references/>
</div>

== 参见 ==

* [[酸酐]]

{{Authority control}}
[[Category:羧酸酐]]
[[Category:化学武器]]
[[Category:催泪剂]]
[[Category:易制毒化学品]]
[[Category:乙酰基化合物]]