<?xml version='1.0' encoding='utf-8'?>
<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>J.A. Leenheer</dc:contributor>
  <dc:contributor>I.F. McVey</dc:contributor>
  <dc:creator>S.E. Cabaniss</dc:creator>
  <dc:date>1998</dc:date>
  <dc:description>&lt;div id="abstracts" class="Abstracts"&gt;&lt;div id="aep-abstract-id12" class="abstract author"&gt;&lt;div id="aep-abstract-sec-id13"&gt;&lt;p&gt;&lt;span&gt;Aqueous&amp;nbsp;attenuated total reflectance&amp;nbsp;Fourier transform infrared (ATR-FTIR) spectra of 18 aliphatic&amp;nbsp;di-carboxylic acids&amp;nbsp;are reported as a function of pH. The spectra show isosbestic points and intensity changes which indicate that Beer's law is obeyed, and peak frequencies lie within previously reported ranges for aqueous carboxylates and pure carboxylic acids. Intensity sharing from the symmetric carboxylate stretch is evident in many cases, so that bands which are nominally due to&amp;nbsp;alkyl groups&amp;nbsp;show increased intensity at higher pH. The asymmetric stretch of the HA&lt;/span&gt;&lt;sup&gt;−&lt;/sup&gt;&lt;span&gt;&amp;nbsp;species is linearly related to the microscopic&amp;nbsp;acidity constantof the H&lt;/span&gt;&lt;sub&gt;2&lt;/sub&gt;A species, with&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;σ&lt;/i&gt;&lt;sub&gt;p&lt;i&gt;K&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&amp;lt;0.25 log units; this relationship falls on the same line as previously observed for&amp;nbsp;mono-carboxylic acids. The linear relationship applies to the acidity constant of the HA&lt;/span&gt;&lt;sup&gt;−&lt;/sup&gt;&lt;span&gt;&amp;nbsp;species only when the two acid groups are well separated (&amp;gt;2 intervening atoms). The results suggest that aqueous&amp;nbsp;ATR-FTIR&amp;nbsp;may be able to estimate `intrinsic' p&lt;/span&gt;&lt;i&gt;K&lt;/i&gt;&lt;sub&gt;a&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;values of carboxylic acids, in addition to providing quantitative estimates of ionization.&lt;/p&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1016/S1386-1425(97)00258-8</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Elsevier</dc:publisher>
  <dc:title>Aqueous infrared carboxylate absorbances: Aliphatic di-acids</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>