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Does the Location of Line-Dash-Wedge Notations Matter?


Line structure of formaldehydeWedge Dash Diagram of 1,2-DichloroethaneDoes the arrangement of atoms around a chiral carbon matter?Single line equilibria notationDoes all organic matter originate from organisms?When does a reaction equation require the reversible sign and when does it not?Absolute configuration when hydrogen (lowest priority group) is in the plane of the page (and not a wedge or dash)R,S Configuration of asymmetric carbon atom when group priority 3 and 4 are not on wedge bond?What does the colon in µ-η2:η2-O2 mean?Hash and Wedge nomenclature













8












$begingroup$


In Line-Dash-Wedge notation, when illustrating that an atom or bond is directed towards or away from the viewer (solid triangle for coming forward, dotted lines for going back), does the location of these lines matter when doing illustrations?



For example, a THC molecule.



THC molecule 1



The two hydrogen atoms there. Could they be placed inside the carbon rings instead of appearing outside, like below?



THC molecule 2



I understand that there's a whole host of issues with that otherwise, but just asking about the triangle and dashes in particular.










share|improve this question









New contributor




Westin Johnson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$







  • 2




    $begingroup$
    Yes they could be placed inside, it doesn't matter.
    $endgroup$
    – Ivan Neretin
    2 days ago















8












$begingroup$


In Line-Dash-Wedge notation, when illustrating that an atom or bond is directed towards or away from the viewer (solid triangle for coming forward, dotted lines for going back), does the location of these lines matter when doing illustrations?



For example, a THC molecule.



THC molecule 1



The two hydrogen atoms there. Could they be placed inside the carbon rings instead of appearing outside, like below?



THC molecule 2



I understand that there's a whole host of issues with that otherwise, but just asking about the triangle and dashes in particular.










share|improve this question









New contributor




Westin Johnson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$







  • 2




    $begingroup$
    Yes they could be placed inside, it doesn't matter.
    $endgroup$
    – Ivan Neretin
    2 days ago













8












8








8





$begingroup$


In Line-Dash-Wedge notation, when illustrating that an atom or bond is directed towards or away from the viewer (solid triangle for coming forward, dotted lines for going back), does the location of these lines matter when doing illustrations?



For example, a THC molecule.



THC molecule 1



The two hydrogen atoms there. Could they be placed inside the carbon rings instead of appearing outside, like below?



THC molecule 2



I understand that there's a whole host of issues with that otherwise, but just asking about the triangle and dashes in particular.










share|improve this question









New contributor




Westin Johnson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$




In Line-Dash-Wedge notation, when illustrating that an atom or bond is directed towards or away from the viewer (solid triangle for coming forward, dotted lines for going back), does the location of these lines matter when doing illustrations?



For example, a THC molecule.



THC molecule 1



The two hydrogen atoms there. Could they be placed inside the carbon rings instead of appearing outside, like below?



THC molecule 2



I understand that there's a whole host of issues with that otherwise, but just asking about the triangle and dashes in particular.







organic-chemistry bond stereochemistry notation






share|improve this question









New contributor




Westin Johnson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question









New contributor




Westin Johnson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question








edited 2 days ago









andselisk

18.5k656122




18.5k656122






New contributor




Westin Johnson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked 2 days ago









Westin JohnsonWestin Johnson

441




441




New contributor




Westin Johnson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





Westin Johnson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Westin Johnson is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







  • 2




    $begingroup$
    Yes they could be placed inside, it doesn't matter.
    $endgroup$
    – Ivan Neretin
    2 days ago












  • 2




    $begingroup$
    Yes they could be placed inside, it doesn't matter.
    $endgroup$
    – Ivan Neretin
    2 days ago







2




2




$begingroup$
Yes they could be placed inside, it doesn't matter.
$endgroup$
– Ivan Neretin
2 days ago




$begingroup$
Yes they could be placed inside, it doesn't matter.
$endgroup$
– Ivan Neretin
2 days ago










1 Answer
1






active

oldest

votes


















11












$begingroup$

Yes, both inner and outer placements are possible with some nuances.



From Graphical representation of stereochemical configuration (IUPAC Recommendations 2006) [1, p. 1926]:




ST-1.3.2: Stereogenic centers at ring fusion atoms



Stereogenic centers at ring fusion atoms should be drawn with hashed wedged or solid wedged bonds to the exocyclic substituent at the fusion atom whenever possible. If necessary, an implicit hydrogen should be made explicit in order to provide an exocyclic substituent to bear the hashed wedged or solid wedged bond. When one of the fusion bonds is oriented vertically and the exocyclic substituent is graphically small (such as a hydrogen or a methyl group, or even such physically larger substituents as a phenyl group represented with a graphically small “Ph” group label), the exocyclic substituent is also
preferentially oriented vertically and opposite to the vertical fusion bond. This orientation is preferred even if it results in the substituent being placed within the ring system, and is particularly common in the depiction of steroids and other natural products.



enter image description here




From Graphical representation standards for chemical structure diagrams (IUPAC Recommendations 2008) [2, p. 354–357]:




GR-4.2.2 Fusion atoms with one substituent drawn



Ring fusion atoms already have three bonds within the ring system. For external ring fusion atoms, the substituent should preferentially be positioned outside the ring system and oriented so that it bisects the angle between the adjacent bonds.



enter image description here



[...]



When two substituted fusion atoms are adjacent, placing both substituents outside the ring system will typically cause them to overlap. In those cases, it is better to draw one of the substituents within the ring system. A substituent drawn in this way should preferentially be drawn exactly vertically or horizontally, whichever direction would minimize overlap with other atoms and bonds.



enter image description here



If a substituted fusion atom is adjacent to an unsubstituted fusion atom, there typically is enough room to orient the substituent either inside or outside the ring system. That substituent should be oriented outside the ring system if all substituents can be oriented outwards, but should preferably be drawn exactly vertically or horizontally if any other substituent is placed within the ring system to avoid
conflict with an adjacent substituent.



enter image description here



Small substituents on the C-8 and C-9 atoms of steroids should be drawn within the ring system in this fashion even if there are no substituents on the adjacent fusion atoms C-10 and C-14. Certain other natural products [23] also have preferred orientations that place substituents within the ring system.



enter image description here



A substituent should not be oriented within a ring system when attached to a fusion atom that lacks any vertical or horizontal fusion bond. The substituent should be oriented outside the ring system, minimizing overlap as best as is possible. Sometimes, it might be possible to reorient the ring system so that the fusion bonds are vertical; the substituents should certainly be placed vertically if so.



enter image description here



It is not acceptable to orient two substituents within the same ring if the ring has fewer than eight atoms. One or both of the substituents should be oriented outside the ring system, minimizing overlap as best as is possible.



enter image description here



Substituents on interior fusion atoms have no option other than being drawn within the ring system. As above, such substituents should preferentially be drawn exactly vertically or horizontally, according to the direction that would minimize overlap with other atoms and bonds.



enter image description here




References



  1. Brecher, J. Graphical Representation of Stereochemical Configuration (IUPAC Recommendations 2006). Pure and Applied Chemistry 2009, 78 (10), 1897–1970. https://doi.org/10.1351/pac200678101897. (Free Access)

  2. Brecher, J. Graphical Representation Standards for Chemical Structure Diagrams (IUPAC Recommendations 2008). Pure and Applied Chemistry 2009, 80 (2), 277–410. https://doi.org/10.1351/pac200880020277. (Free Access)





share|improve this answer











$endgroup$












  • $begingroup$
    I have issues with some of the structures labelled "not acceptable." Yeah, some of them are not acceptable given overlap, but others are quite valid from first principles. Most particularly, in the section starting with "Small substituents on the C-8 and C-9," it seems extremely arbitrary to call the right structure "not acceptable."
    $endgroup$
    – Zhe
    2 days ago






  • 2




    $begingroup$
    @Zhe The way I interpret that section is that for particular classes of compounds (steroids for one) there's conventions on how you place those hydrogens, such that they will match across a diverse compound series (and with reader expectations). It's sort of like the conventions on how to orient certain molecules (e.g. for steroids the 5-member ring is in the upper right) - other ways of placing them (e.g. 5-member ring on the bottom or on the lower left) aren't technically incorrect, but are so against convention that you shouldn't do it.
    $endgroup$
    – R.M.
    2 days ago






  • 1




    $begingroup$
    That sounds 100% reasonable. Though I would strongly prefer the language of "unconventional" or "dispreferred" instead of "not acceptable."
    $endgroup$
    – Zhe
    2 days ago










Your Answer





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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









11












$begingroup$

Yes, both inner and outer placements are possible with some nuances.



From Graphical representation of stereochemical configuration (IUPAC Recommendations 2006) [1, p. 1926]:




ST-1.3.2: Stereogenic centers at ring fusion atoms



Stereogenic centers at ring fusion atoms should be drawn with hashed wedged or solid wedged bonds to the exocyclic substituent at the fusion atom whenever possible. If necessary, an implicit hydrogen should be made explicit in order to provide an exocyclic substituent to bear the hashed wedged or solid wedged bond. When one of the fusion bonds is oriented vertically and the exocyclic substituent is graphically small (such as a hydrogen or a methyl group, or even such physically larger substituents as a phenyl group represented with a graphically small “Ph” group label), the exocyclic substituent is also
preferentially oriented vertically and opposite to the vertical fusion bond. This orientation is preferred even if it results in the substituent being placed within the ring system, and is particularly common in the depiction of steroids and other natural products.



enter image description here




From Graphical representation standards for chemical structure diagrams (IUPAC Recommendations 2008) [2, p. 354–357]:




GR-4.2.2 Fusion atoms with one substituent drawn



Ring fusion atoms already have three bonds within the ring system. For external ring fusion atoms, the substituent should preferentially be positioned outside the ring system and oriented so that it bisects the angle between the adjacent bonds.



enter image description here



[...]



When two substituted fusion atoms are adjacent, placing both substituents outside the ring system will typically cause them to overlap. In those cases, it is better to draw one of the substituents within the ring system. A substituent drawn in this way should preferentially be drawn exactly vertically or horizontally, whichever direction would minimize overlap with other atoms and bonds.



enter image description here



If a substituted fusion atom is adjacent to an unsubstituted fusion atom, there typically is enough room to orient the substituent either inside or outside the ring system. That substituent should be oriented outside the ring system if all substituents can be oriented outwards, but should preferably be drawn exactly vertically or horizontally if any other substituent is placed within the ring system to avoid
conflict with an adjacent substituent.



enter image description here



Small substituents on the C-8 and C-9 atoms of steroids should be drawn within the ring system in this fashion even if there are no substituents on the adjacent fusion atoms C-10 and C-14. Certain other natural products [23] also have preferred orientations that place substituents within the ring system.



enter image description here



A substituent should not be oriented within a ring system when attached to a fusion atom that lacks any vertical or horizontal fusion bond. The substituent should be oriented outside the ring system, minimizing overlap as best as is possible. Sometimes, it might be possible to reorient the ring system so that the fusion bonds are vertical; the substituents should certainly be placed vertically if so.



enter image description here



It is not acceptable to orient two substituents within the same ring if the ring has fewer than eight atoms. One or both of the substituents should be oriented outside the ring system, minimizing overlap as best as is possible.



enter image description here



Substituents on interior fusion atoms have no option other than being drawn within the ring system. As above, such substituents should preferentially be drawn exactly vertically or horizontally, according to the direction that would minimize overlap with other atoms and bonds.



enter image description here




References



  1. Brecher, J. Graphical Representation of Stereochemical Configuration (IUPAC Recommendations 2006). Pure and Applied Chemistry 2009, 78 (10), 1897–1970. https://doi.org/10.1351/pac200678101897. (Free Access)

  2. Brecher, J. Graphical Representation Standards for Chemical Structure Diagrams (IUPAC Recommendations 2008). Pure and Applied Chemistry 2009, 80 (2), 277–410. https://doi.org/10.1351/pac200880020277. (Free Access)





share|improve this answer











$endgroup$












  • $begingroup$
    I have issues with some of the structures labelled "not acceptable." Yeah, some of them are not acceptable given overlap, but others are quite valid from first principles. Most particularly, in the section starting with "Small substituents on the C-8 and C-9," it seems extremely arbitrary to call the right structure "not acceptable."
    $endgroup$
    – Zhe
    2 days ago






  • 2




    $begingroup$
    @Zhe The way I interpret that section is that for particular classes of compounds (steroids for one) there's conventions on how you place those hydrogens, such that they will match across a diverse compound series (and with reader expectations). It's sort of like the conventions on how to orient certain molecules (e.g. for steroids the 5-member ring is in the upper right) - other ways of placing them (e.g. 5-member ring on the bottom or on the lower left) aren't technically incorrect, but are so against convention that you shouldn't do it.
    $endgroup$
    – R.M.
    2 days ago






  • 1




    $begingroup$
    That sounds 100% reasonable. Though I would strongly prefer the language of "unconventional" or "dispreferred" instead of "not acceptable."
    $endgroup$
    – Zhe
    2 days ago















11












$begingroup$

Yes, both inner and outer placements are possible with some nuances.



From Graphical representation of stereochemical configuration (IUPAC Recommendations 2006) [1, p. 1926]:




ST-1.3.2: Stereogenic centers at ring fusion atoms



Stereogenic centers at ring fusion atoms should be drawn with hashed wedged or solid wedged bonds to the exocyclic substituent at the fusion atom whenever possible. If necessary, an implicit hydrogen should be made explicit in order to provide an exocyclic substituent to bear the hashed wedged or solid wedged bond. When one of the fusion bonds is oriented vertically and the exocyclic substituent is graphically small (such as a hydrogen or a methyl group, or even such physically larger substituents as a phenyl group represented with a graphically small “Ph” group label), the exocyclic substituent is also
preferentially oriented vertically and opposite to the vertical fusion bond. This orientation is preferred even if it results in the substituent being placed within the ring system, and is particularly common in the depiction of steroids and other natural products.



enter image description here




From Graphical representation standards for chemical structure diagrams (IUPAC Recommendations 2008) [2, p. 354–357]:




GR-4.2.2 Fusion atoms with one substituent drawn



Ring fusion atoms already have three bonds within the ring system. For external ring fusion atoms, the substituent should preferentially be positioned outside the ring system and oriented so that it bisects the angle between the adjacent bonds.



enter image description here



[...]



When two substituted fusion atoms are adjacent, placing both substituents outside the ring system will typically cause them to overlap. In those cases, it is better to draw one of the substituents within the ring system. A substituent drawn in this way should preferentially be drawn exactly vertically or horizontally, whichever direction would minimize overlap with other atoms and bonds.



enter image description here



If a substituted fusion atom is adjacent to an unsubstituted fusion atom, there typically is enough room to orient the substituent either inside or outside the ring system. That substituent should be oriented outside the ring system if all substituents can be oriented outwards, but should preferably be drawn exactly vertically or horizontally if any other substituent is placed within the ring system to avoid
conflict with an adjacent substituent.



enter image description here



Small substituents on the C-8 and C-9 atoms of steroids should be drawn within the ring system in this fashion even if there are no substituents on the adjacent fusion atoms C-10 and C-14. Certain other natural products [23] also have preferred orientations that place substituents within the ring system.



enter image description here



A substituent should not be oriented within a ring system when attached to a fusion atom that lacks any vertical or horizontal fusion bond. The substituent should be oriented outside the ring system, minimizing overlap as best as is possible. Sometimes, it might be possible to reorient the ring system so that the fusion bonds are vertical; the substituents should certainly be placed vertically if so.



enter image description here



It is not acceptable to orient two substituents within the same ring if the ring has fewer than eight atoms. One or both of the substituents should be oriented outside the ring system, minimizing overlap as best as is possible.



enter image description here



Substituents on interior fusion atoms have no option other than being drawn within the ring system. As above, such substituents should preferentially be drawn exactly vertically or horizontally, according to the direction that would minimize overlap with other atoms and bonds.



enter image description here




References



  1. Brecher, J. Graphical Representation of Stereochemical Configuration (IUPAC Recommendations 2006). Pure and Applied Chemistry 2009, 78 (10), 1897–1970. https://doi.org/10.1351/pac200678101897. (Free Access)

  2. Brecher, J. Graphical Representation Standards for Chemical Structure Diagrams (IUPAC Recommendations 2008). Pure and Applied Chemistry 2009, 80 (2), 277–410. https://doi.org/10.1351/pac200880020277. (Free Access)





share|improve this answer











$endgroup$












  • $begingroup$
    I have issues with some of the structures labelled "not acceptable." Yeah, some of them are not acceptable given overlap, but others are quite valid from first principles. Most particularly, in the section starting with "Small substituents on the C-8 and C-9," it seems extremely arbitrary to call the right structure "not acceptable."
    $endgroup$
    – Zhe
    2 days ago






  • 2




    $begingroup$
    @Zhe The way I interpret that section is that for particular classes of compounds (steroids for one) there's conventions on how you place those hydrogens, such that they will match across a diverse compound series (and with reader expectations). It's sort of like the conventions on how to orient certain molecules (e.g. for steroids the 5-member ring is in the upper right) - other ways of placing them (e.g. 5-member ring on the bottom or on the lower left) aren't technically incorrect, but are so against convention that you shouldn't do it.
    $endgroup$
    – R.M.
    2 days ago






  • 1




    $begingroup$
    That sounds 100% reasonable. Though I would strongly prefer the language of "unconventional" or "dispreferred" instead of "not acceptable."
    $endgroup$
    – Zhe
    2 days ago













11












11








11





$begingroup$

Yes, both inner and outer placements are possible with some nuances.



From Graphical representation of stereochemical configuration (IUPAC Recommendations 2006) [1, p. 1926]:




ST-1.3.2: Stereogenic centers at ring fusion atoms



Stereogenic centers at ring fusion atoms should be drawn with hashed wedged or solid wedged bonds to the exocyclic substituent at the fusion atom whenever possible. If necessary, an implicit hydrogen should be made explicit in order to provide an exocyclic substituent to bear the hashed wedged or solid wedged bond. When one of the fusion bonds is oriented vertically and the exocyclic substituent is graphically small (such as a hydrogen or a methyl group, or even such physically larger substituents as a phenyl group represented with a graphically small “Ph” group label), the exocyclic substituent is also
preferentially oriented vertically and opposite to the vertical fusion bond. This orientation is preferred even if it results in the substituent being placed within the ring system, and is particularly common in the depiction of steroids and other natural products.



enter image description here




From Graphical representation standards for chemical structure diagrams (IUPAC Recommendations 2008) [2, p. 354–357]:




GR-4.2.2 Fusion atoms with one substituent drawn



Ring fusion atoms already have three bonds within the ring system. For external ring fusion atoms, the substituent should preferentially be positioned outside the ring system and oriented so that it bisects the angle between the adjacent bonds.



enter image description here



[...]



When two substituted fusion atoms are adjacent, placing both substituents outside the ring system will typically cause them to overlap. In those cases, it is better to draw one of the substituents within the ring system. A substituent drawn in this way should preferentially be drawn exactly vertically or horizontally, whichever direction would minimize overlap with other atoms and bonds.



enter image description here



If a substituted fusion atom is adjacent to an unsubstituted fusion atom, there typically is enough room to orient the substituent either inside or outside the ring system. That substituent should be oriented outside the ring system if all substituents can be oriented outwards, but should preferably be drawn exactly vertically or horizontally if any other substituent is placed within the ring system to avoid
conflict with an adjacent substituent.



enter image description here



Small substituents on the C-8 and C-9 atoms of steroids should be drawn within the ring system in this fashion even if there are no substituents on the adjacent fusion atoms C-10 and C-14. Certain other natural products [23] also have preferred orientations that place substituents within the ring system.



enter image description here



A substituent should not be oriented within a ring system when attached to a fusion atom that lacks any vertical or horizontal fusion bond. The substituent should be oriented outside the ring system, minimizing overlap as best as is possible. Sometimes, it might be possible to reorient the ring system so that the fusion bonds are vertical; the substituents should certainly be placed vertically if so.



enter image description here



It is not acceptable to orient two substituents within the same ring if the ring has fewer than eight atoms. One or both of the substituents should be oriented outside the ring system, minimizing overlap as best as is possible.



enter image description here



Substituents on interior fusion atoms have no option other than being drawn within the ring system. As above, such substituents should preferentially be drawn exactly vertically or horizontally, according to the direction that would minimize overlap with other atoms and bonds.



enter image description here




References



  1. Brecher, J. Graphical Representation of Stereochemical Configuration (IUPAC Recommendations 2006). Pure and Applied Chemistry 2009, 78 (10), 1897–1970. https://doi.org/10.1351/pac200678101897. (Free Access)

  2. Brecher, J. Graphical Representation Standards for Chemical Structure Diagrams (IUPAC Recommendations 2008). Pure and Applied Chemistry 2009, 80 (2), 277–410. https://doi.org/10.1351/pac200880020277. (Free Access)





share|improve this answer











$endgroup$



Yes, both inner and outer placements are possible with some nuances.



From Graphical representation of stereochemical configuration (IUPAC Recommendations 2006) [1, p. 1926]:




ST-1.3.2: Stereogenic centers at ring fusion atoms



Stereogenic centers at ring fusion atoms should be drawn with hashed wedged or solid wedged bonds to the exocyclic substituent at the fusion atom whenever possible. If necessary, an implicit hydrogen should be made explicit in order to provide an exocyclic substituent to bear the hashed wedged or solid wedged bond. When one of the fusion bonds is oriented vertically and the exocyclic substituent is graphically small (such as a hydrogen or a methyl group, or even such physically larger substituents as a phenyl group represented with a graphically small “Ph” group label), the exocyclic substituent is also
preferentially oriented vertically and opposite to the vertical fusion bond. This orientation is preferred even if it results in the substituent being placed within the ring system, and is particularly common in the depiction of steroids and other natural products.



enter image description here




From Graphical representation standards for chemical structure diagrams (IUPAC Recommendations 2008) [2, p. 354–357]:




GR-4.2.2 Fusion atoms with one substituent drawn



Ring fusion atoms already have three bonds within the ring system. For external ring fusion atoms, the substituent should preferentially be positioned outside the ring system and oriented so that it bisects the angle between the adjacent bonds.



enter image description here



[...]



When two substituted fusion atoms are adjacent, placing both substituents outside the ring system will typically cause them to overlap. In those cases, it is better to draw one of the substituents within the ring system. A substituent drawn in this way should preferentially be drawn exactly vertically or horizontally, whichever direction would minimize overlap with other atoms and bonds.



enter image description here



If a substituted fusion atom is adjacent to an unsubstituted fusion atom, there typically is enough room to orient the substituent either inside or outside the ring system. That substituent should be oriented outside the ring system if all substituents can be oriented outwards, but should preferably be drawn exactly vertically or horizontally if any other substituent is placed within the ring system to avoid
conflict with an adjacent substituent.



enter image description here



Small substituents on the C-8 and C-9 atoms of steroids should be drawn within the ring system in this fashion even if there are no substituents on the adjacent fusion atoms C-10 and C-14. Certain other natural products [23] also have preferred orientations that place substituents within the ring system.



enter image description here



A substituent should not be oriented within a ring system when attached to a fusion atom that lacks any vertical or horizontal fusion bond. The substituent should be oriented outside the ring system, minimizing overlap as best as is possible. Sometimes, it might be possible to reorient the ring system so that the fusion bonds are vertical; the substituents should certainly be placed vertically if so.



enter image description here



It is not acceptable to orient two substituents within the same ring if the ring has fewer than eight atoms. One or both of the substituents should be oriented outside the ring system, minimizing overlap as best as is possible.



enter image description here



Substituents on interior fusion atoms have no option other than being drawn within the ring system. As above, such substituents should preferentially be drawn exactly vertically or horizontally, according to the direction that would minimize overlap with other atoms and bonds.



enter image description here




References



  1. Brecher, J. Graphical Representation of Stereochemical Configuration (IUPAC Recommendations 2006). Pure and Applied Chemistry 2009, 78 (10), 1897–1970. https://doi.org/10.1351/pac200678101897. (Free Access)

  2. Brecher, J. Graphical Representation Standards for Chemical Structure Diagrams (IUPAC Recommendations 2008). Pure and Applied Chemistry 2009, 80 (2), 277–410. https://doi.org/10.1351/pac200880020277. (Free Access)






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edited 2 days ago

























answered 2 days ago









andseliskandselisk

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  • $begingroup$
    I have issues with some of the structures labelled "not acceptable." Yeah, some of them are not acceptable given overlap, but others are quite valid from first principles. Most particularly, in the section starting with "Small substituents on the C-8 and C-9," it seems extremely arbitrary to call the right structure "not acceptable."
    $endgroup$
    – Zhe
    2 days ago






  • 2




    $begingroup$
    @Zhe The way I interpret that section is that for particular classes of compounds (steroids for one) there's conventions on how you place those hydrogens, such that they will match across a diverse compound series (and with reader expectations). It's sort of like the conventions on how to orient certain molecules (e.g. for steroids the 5-member ring is in the upper right) - other ways of placing them (e.g. 5-member ring on the bottom or on the lower left) aren't technically incorrect, but are so against convention that you shouldn't do it.
    $endgroup$
    – R.M.
    2 days ago






  • 1




    $begingroup$
    That sounds 100% reasonable. Though I would strongly prefer the language of "unconventional" or "dispreferred" instead of "not acceptable."
    $endgroup$
    – Zhe
    2 days ago
















  • $begingroup$
    I have issues with some of the structures labelled "not acceptable." Yeah, some of them are not acceptable given overlap, but others are quite valid from first principles. Most particularly, in the section starting with "Small substituents on the C-8 and C-9," it seems extremely arbitrary to call the right structure "not acceptable."
    $endgroup$
    – Zhe
    2 days ago






  • 2




    $begingroup$
    @Zhe The way I interpret that section is that for particular classes of compounds (steroids for one) there's conventions on how you place those hydrogens, such that they will match across a diverse compound series (and with reader expectations). It's sort of like the conventions on how to orient certain molecules (e.g. for steroids the 5-member ring is in the upper right) - other ways of placing them (e.g. 5-member ring on the bottom or on the lower left) aren't technically incorrect, but are so against convention that you shouldn't do it.
    $endgroup$
    – R.M.
    2 days ago






  • 1




    $begingroup$
    That sounds 100% reasonable. Though I would strongly prefer the language of "unconventional" or "dispreferred" instead of "not acceptable."
    $endgroup$
    – Zhe
    2 days ago















$begingroup$
I have issues with some of the structures labelled "not acceptable." Yeah, some of them are not acceptable given overlap, but others are quite valid from first principles. Most particularly, in the section starting with "Small substituents on the C-8 and C-9," it seems extremely arbitrary to call the right structure "not acceptable."
$endgroup$
– Zhe
2 days ago




$begingroup$
I have issues with some of the structures labelled "not acceptable." Yeah, some of them are not acceptable given overlap, but others are quite valid from first principles. Most particularly, in the section starting with "Small substituents on the C-8 and C-9," it seems extremely arbitrary to call the right structure "not acceptable."
$endgroup$
– Zhe
2 days ago




2




2




$begingroup$
@Zhe The way I interpret that section is that for particular classes of compounds (steroids for one) there's conventions on how you place those hydrogens, such that they will match across a diverse compound series (and with reader expectations). It's sort of like the conventions on how to orient certain molecules (e.g. for steroids the 5-member ring is in the upper right) - other ways of placing them (e.g. 5-member ring on the bottom or on the lower left) aren't technically incorrect, but are so against convention that you shouldn't do it.
$endgroup$
– R.M.
2 days ago




$begingroup$
@Zhe The way I interpret that section is that for particular classes of compounds (steroids for one) there's conventions on how you place those hydrogens, such that they will match across a diverse compound series (and with reader expectations). It's sort of like the conventions on how to orient certain molecules (e.g. for steroids the 5-member ring is in the upper right) - other ways of placing them (e.g. 5-member ring on the bottom or on the lower left) aren't technically incorrect, but are so against convention that you shouldn't do it.
$endgroup$
– R.M.
2 days ago




1




1




$begingroup$
That sounds 100% reasonable. Though I would strongly prefer the language of "unconventional" or "dispreferred" instead of "not acceptable."
$endgroup$
– Zhe
2 days ago




$begingroup$
That sounds 100% reasonable. Though I would strongly prefer the language of "unconventional" or "dispreferred" instead of "not acceptable."
$endgroup$
– Zhe
2 days ago










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