Oxidation/Reduction of Biomolecules - Revision history

Bes: /* Bulk Electrolysis/Electrosynthesis */

2019-11-17T14:35:28Z

Bulk Electrolysis/Electrosynthesis

Bes: /* Bulk Electrolysis/Electrosynthesis */

2019-11-17T14:34:23Z

Bulk Electrolysis/Electrosynthesis

Bes: /* Bulk Electrolysis/Electrosynthesis */

2019-11-17T14:33:57Z

Bulk Electrolysis/Electrosynthesis

Bes: /* Analytical Chemistry Introduction */

2019-11-17T14:33:00Z

Analytical Chemistry Introduction

Bes: /* Analytical Chemistry Introduction */

2019-11-09T14:40:58Z

Analytical Chemistry Introduction

Bes: /* General Chemistry Introduction */

2019-11-09T14:25:51Z

General Chemistry Introduction

Bes: /* General Chemistry Introduction */

2019-11-09T14:24:32Z

General Chemistry Introduction

Bes: /* General Chemistry Introduction */

2019-11-09T14:23:29Z

General Chemistry Introduction

Bes: /* General Chemistry Introduction */

2019-11-09T14:20:52Z

General Chemistry Introduction

Bes: /* Introduction */

2018-07-18T12:27:03Z

Introduction

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	==Bulk Electrolysis/Electrosynthesis==		==Bulk Electrolysis/Electrosynthesis==
−	[[:Media:cen-09743-cover.pdf]]	+	[[:Media:cen-09743-cover.pdf\|'''AMPING UP THE PHARMA LAB''' Companies explore the potential of electrochemistry]]

← Older revision		Revision as of 14:34, 17 November 2019
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	==Bulk Electrolysis/Electrosynthesis==		==Bulk Electrolysis/Electrosynthesis==
−	[[:~~File~~:cen-09743-cover.pdf]]	+	[[:Media:cen-09743-cover.pdf]]

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	==Bulk Electrolysis/Electrosynthesis==		==Bulk Electrolysis/Electrosynthesis==
		+	[[:File:cen-09743-cover.pdf]]

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	Let us consider an example more related to molecules of biological origin, like ascorbic acid and α-tocopherol, also known as vitamin C and E, respectively and glutathione (in the figure below the label is “reduced” glutathione. This is an indication that the thiol moiety is an R–S-H. There is also “oxidized” glutathione where the thiol moiety is R-S-S-R, this is clearly a bad/unclear naming convention).		Let us consider an example more related to molecules of biological origin, like ascorbic acid and α-tocopherol, also known as vitamin C and E, respectively and glutathione (in the figure below the label is “reduced” glutathione. This is an indication that the thiol moiety is an R–S-H. There is also “oxidized” glutathione where the thiol moiety is R-S-S-R, this is clearly a bad/unclear naming convention).
		+
		+	==Bulk Electrolysis/Electrosynthesis==

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 ==Analytical Chemistry Introduction==
-We can be more quantitative and use the standard reduction potentials (see [[Chemistry02-07-2002.pdf|Chemistry Reference Document]]). Note that each redox reaction has one oxidation reaction and one reduction reaction, but the tabulated values are only for the reduction potentials. We can lookup the reduction half reactions (inverse of Eq. 3 and Eq. 4):
+In the above conversation we used the ''activity series'' to indicate whether a reaction would occur or not (or if the reverse reaction would occur). We can be more quantitative by using the standard reduction potentials (see [[Chemistry02-07-2002.pdf|Chemistry Reference Document]]). Each redox reaction consist of one oxidation reaction and one reduction reaction, but the tabulated values are only for the ''reduction potentials''. We can lookup the reduction half reactions (inverse of Eq. 3 and Eq. 4):
-:Ered (V)
+:E<sub>red</sub> (V)
-:Fe3+(aq) + 3e- → Fe(s)	-0.036
+:Fe<sup>3+</sup>(aq) + 3e- → Fe(s) = -0.036
-:Cu2+(aq) + 2e- → Cu(s)	+0.34
+:Cu<sup>2+</sup>(aq) + 2e- → Cu(s) = +0.34
-To compensate for the oxidation reaction (Eq. 3), we need to reverse the iron reduction potential to make it oxidation and in doing so we change the sign of the Ered. In additon, if there is a stoichiemetric coefficient, we need to multiple the potential by that value:
+To compensate for the oxidation reaction (Eq. 3), we need to reverse the iron reduction potential to make it oxidation and in doing so we change the sign of the Ered. In addition, if there is a stoichiometric coefficient, we need to multiple the potential by that value:
-	Eredox (V)
+	E<sub>redox</sub> (V)
-x [Fe(s) → Fe3+(aq) + 3e-]	2x [+0.036] = 0.072 V
+x [Fe(s) → Fe<sup>3+</sup>(aq) + 3e-]	2x [+0.036] = 0.072 V
-x [Cu2+(aq) + 2e- → Cu(s)]	3x [+0.34] = 1.02 V
+x [Cu<sup>2+</sup>(aq) + 2e- → Cu(s)]	3x [+0.34] = 1.02 V
 Adding together the potentials we arrive at 1.092V. If this redox reaction potential is a positive value, then the reaction will proceed as written. If the reaction was written as;
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 then the overall redox potential for this reaction would be –1.092 V and hence would not proceed as written (in fact you could assume the reverse reaction would occur). When using tabulated redox potentials, it is important that you pay close attention to the details of the table contents that state the standard conditions that apply and the reference potential (in this case the standard hydrogen electrode - SHE).
-You might find yourself asking how does one determine the reduction potential for a given chemical species. In general redox potentials can be determined using cyclic voltameetry. See:
+You might find yourself asking how does one determine the reduction potential for a given chemical species. In general redox potentials can be determined using cyclic voltammetry. See:
 http://www-biol.paisley.ac.uk/marco/Enzyme_Electrode/Chapter1/Cyclic_Voltammetry1.htm
 Let us consider an example more related to molecules of biological origin, like ascorbic acid and α-tocopherol, also known as vitamin C and E, respectively and glutathione (in the figure below the label is “reduced” glutathione. This is an indication that the thiol moiety is an R–S-H. There is also “oxidized” glutathione where the thiol moiety is R-S-S-R, this is clearly a bad/unclear naming convention).

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 First off, this equation is not balanced. Taking into account that we must balance both elements and electrons:
-:Fe(s) + 3 Cu<sup>2+</sup>(aq) → Fe<sup>3+</sup>(aq) + 3 Cu(s) '''''(eq. 2)'''''
+:2 Fe(s) + 3 Cu<sup>2+</sup>(aq) → 2 Fe<sup>3+</sup>(aq) + 3 Cu(s) '''''(eq. 2)'''''
 In this example, Fe(s) is being oxidized and Cu<sup>2+</sup>(aq) is being reduced; Fe(s) is the reducing agent and Cu<sup>2+</sup>(aq) is the oxidizing agent. We often think of these redox reactions in terms of oxidation - reduction half reactions shown in eq 3. and eq. 4:

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 :Fe(s) + Cu<sup>2+</sup>(aq) → Fe<sup>3+</sup>(aq) + Cu(s) '''''(eq. 1)'''''
-First off, this equation is not balanced. Please balance the redox equation below (recall that you must balance element and electrons):
+First off, this equation is not balanced. Taking into account that we must balance both elements and electrons:
-:___ Fe(s) + ___ Cu<sup>2+</sup>(aq) → ___ Fe<sup>3+</sup>(aq) + ___ Cu(s) '''''(eq. 2)'''''
+:2 Fe(s) + 3 Cu<sup>2+</sup>(aq) → 2 Fe<sup>3+</sup>(aq) + 3 Cu(s) '''''(eq. 2)'''''
 In this example, Fe(s) is being oxidized and Cu<sup>2+</sup>(aq) is being reduced; Fe(s) is the reducing agent and Cu<sup>2+</sup>(aq) is the oxidizing agent. We often think of these redox reactions in terms of oxidation - reduction half reactions shown in eq 3. and eq. 4:

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 ==General Chemistry Introduction==
-The loss of an electron from a chemical species is referred to as '''''oxidation'''''; the gain of an electron by a chemical species is called '''''reduction'''''. The commonly used acronyms to remember these terms are: '''LEO-GER''' for '''L'''oss of '''E'''lectron is '''O'''xidation – '''G'''ain of '''E'''lectron is '''R'''eduction or '''OIL RIG''' for '''O'''xidation Is '''L'''oss '''R'''eduction Is '''G'''ain. Oxidation-reduction chemistry, also known as '''''redox''''' chemistry, is further complicated by the terms '''''reducing agent''''' and '''''oxidizing agent'''''. A reducing agent is a chemical species that reduces another chemical species; in the process the reducing agent becomes oxidized. Likewise, an oxidizing agent is a chemical species that oxidizes another chemical species; in the process the oxidizing agent becomes reduced. An example of a redox reaction is shown below:
+The loss of an electron from a chemical species is referred to as '''''oxidation'''''; the gain of an electron by a chemical species is called '''''reduction'''''. The commonly used acronyms to remember these terms are: '''LEO-GER''' for '''L'''oss of '''E'''lectron is '''O'''xidation – '''G'''ain of '''E'''lectron is '''R'''eduction or '''OIL RIG''' for '''O'''xidation '''I'''s '''L'''oss '''R'''eduction '''I'''s '''G'''ain. Oxidation-reduction chemistry, also known as '''''redox''''' chemistry, is further complicated by the terms '''''reducing agent''''' and '''''oxidizing agent'''''. A reducing agent is a chemical species that reduces another chemical species; in the process the reducing agent becomes oxidized. Likewise, an oxidizing agent is a chemical species that oxidizes another chemical species; in the process the oxidizing agent becomes reduced. An example of a redox reaction is shown below:
 :Fe(s) + Cu<sup>2+</sup>(aq) → Fe<sup>3+</sup>(aq) + Cu(s) '''''(eq. 1)'''''

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−	When a single electron is taken away from a chemical species (chemical oxidation), this results in a '''''radical'''''; a radical is any chemical species with an unpaired electron; radicals can also form via 1-electron reduction. Radicals formed from chemical oxidation have a tendency to re-acquire the lost electron; radicals formed from chemical reduction, have a tendency to give up the gained electron. For this reason radicals are considered harmful since they can take electrons away from or give electrons to biomolecules like DNA, proteins, lipids, and other bioactive chemicals. The term "free radical" is often used in place of the more general term "radical," but has ~~not~~ clear physical or chemical meaning. Although most free radicals are transient (have short half-lives), some chemical structures have the unpaired electron highly delocalized or localized on a chemically unreactive moiety leading to longer half-lives.	+	When a single electron is taken away from a chemical species (chemical oxidation), this results in a '''''radical'''''; a radical is any chemical species with an unpaired electron; radicals can also form via 1-electron reduction. Radicals formed from chemical oxidation have a tendency to re-acquire the lost electron; radicals formed from chemical reduction, have a tendency to give up the gained electron. For this reason radicals are considered harmful since they can take electrons away from or give electrons to biomolecules like DNA, proteins, lipids, and other bioactive chemicals. The term "free radical" is often used in place of the more general term "radical," but has no clear physical or chemical meaning. Although most free radicals are transient (have short half-lives), some chemical structures have the unpaired electron highly delocalized or localized on a chemically unreactive moiety leading to longer half-lives.

	'''Oxidation-reduction reactions which involve the formation of free radical intermediates have product outcomes that are not well understood."		'''Oxidation-reduction reactions which involve the formation of free radical intermediates have product outcomes that are not well understood."