Are there chiral compounds that don't rotate plane-polarized light?
Clash Royale CLAN TAG#URR8PPP
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I know that meso compounds have chiral centers but don't rotate plane-polarized light, and I know that there can be non-traditionally chiral compounds (e.g. ones with large substituents that prohibit much rotation around single bonds) that can still rotate light, but I haven't been able to find any molecules that are chiral but don't rotate plane-polarized light (or rotate it impossibly little). I'm imagining something like an enantiomeric pair connected by one single bond with a slight modification to one that makes it have similar optical activity but not actually be identical (so the final molecule is indeed chiral), but I don't know exactly how to make it work.
stereochemistry chirality optical-properties
asked 3 hours ago
Carl Schildkraut
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up vote
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I know that meso compounds have chiral centers but don't rotate plane-polarized light, and I know that there can be non-traditionally chiral compounds (e.g. ones with large substituents that prohibit much rotation around single bonds) that can still rotate light, but I haven't been able to find any molecules that are chiral but don't rotate plane-polarized light (or rotate it impossibly little). I'm imagining something like an enantiomeric pair connected by one single bond with a slight modification to one that makes it have similar optical activity but not actually be identical (so the final molecule is indeed chiral), but I don't know exactly how to make it work.
stereochemistry chirality optical-properties
asked 3 hours ago
Carl Schildkraut
1163
New contributor
Carl Schildkraut is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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Achiral compounds don't rotate light.
– Ivan Neretin
3 hours ago
@IvanNeretin My source for that claim was the first answer to this post on Quora. The reasoning seems OK to me, but I'm not knowledgeable enough about stereochemistry to accurately confirm or dispute it.
– Carl Schildkraut
3 hours ago
1
@IvanNeretin More precisely (as I suspect the questioner intended) compounds with no chiral centres can be chiral because of restricted rotation or other geometric features eg hexahelicene.
– matt_black
2 hours ago
Depends on what you mean by "do they rotate?" What if they don't rotate light by a measurable amount? I'm sure I can contrive a number of compounds where that is the case.
– Zhe
2 hours ago
Compounds without chiral centers can be chiral all right.
– Ivan Neretin
2 hours ago
 |Â
show 2 more comments
up vote
3
down vote
favorite
up vote
3
down vote
favorite
I know that meso compounds have chiral centers but don't rotate plane-polarized light, and I know that there can be non-traditionally chiral compounds (e.g. ones with large substituents that prohibit much rotation around single bonds) that can still rotate light, but I haven't been able to find any molecules that are chiral but don't rotate plane-polarized light (or rotate it impossibly little). I'm imagining something like an enantiomeric pair connected by one single bond with a slight modification to one that makes it have similar optical activity but not actually be identical (so the final molecule is indeed chiral), but I don't know exactly how to make it work.
stereochemistry chirality optical-properties
asked 3 hours ago
Carl Schildkraut
1163
New contributor
Carl Schildkraut is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I know that meso compounds have chiral centers but don't rotate plane-polarized light, and I know that there can be non-traditionally chiral compounds (e.g. ones with large substituents that prohibit much rotation around single bonds) that can still rotate light, but I haven't been able to find any molecules that are chiral but don't rotate plane-polarized light (or rotate it impossibly little). I'm imagining something like an enantiomeric pair connected by one single bond with a slight modification to one that makes it have similar optical activity but not actually be identical (so the final molecule is indeed chiral), but I don't know exactly how to make it work.
stereochemistry chirality optical-properties
stereochemistry chirality optical-properties
asked 3 hours ago
Carl Schildkraut
1163
New contributor
Carl Schildkraut is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 3 hours ago
Carl Schildkraut
1163
New contributor
Carl Schildkraut is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 1 hour ago
asked 3 hours ago
Carl Schildkraut
1163
New contributor
Carl Schildkraut is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 3 hours ago
Carl Schildkraut
1163
asked 3 hours ago
Carl Schildkraut
1163
1163
New contributor
Carl Schildkraut is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Carl Schildkraut is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Carl Schildkraut is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Achiral compounds don't rotate light.
– Ivan Neretin
3 hours ago
@IvanNeretin My source for that claim was the first answer to this post on Quora. The reasoning seems OK to me, but I'm not knowledgeable enough about stereochemistry to accurately confirm or dispute it.
– Carl Schildkraut
3 hours ago
1
@IvanNeretin More precisely (as I suspect the questioner intended) compounds with no chiral centres can be chiral because of restricted rotation or other geometric features eg hexahelicene.
– matt_black
2 hours ago
Depends on what you mean by "do they rotate?" What if they don't rotate light by a measurable amount? I'm sure I can contrive a number of compounds where that is the case.
– Zhe
2 hours ago
Compounds without chiral centers can be chiral all right.
– Ivan Neretin
2 hours ago
 |Â
show 2 more comments
Achiral compounds don't rotate light.
– Ivan Neretin
3 hours ago
@IvanNeretin My source for that claim was the first answer to this post on Quora. The reasoning seems OK to me, but I'm not knowledgeable enough about stereochemistry to accurately confirm or dispute it.
– Carl Schildkraut
3 hours ago
1
@IvanNeretin More precisely (as I suspect the questioner intended) compounds with no chiral centres can be chiral because of restricted rotation or other geometric features eg hexahelicene.
– matt_black
2 hours ago
Depends on what you mean by "do they rotate?" What if they don't rotate light by a measurable amount? I'm sure I can contrive a number of compounds where that is the case.
– Zhe
2 hours ago
Compounds without chiral centers can be chiral all right.
– Ivan Neretin
2 hours ago
Achiral compounds don't rotate light.
– Ivan Neretin
3 hours ago
Achiral compounds don't rotate light.
– Ivan Neretin
3 hours ago
@IvanNeretin My source for that claim was the first answer to this post on Quora. The reasoning seems OK to me, but I'm not knowledgeable enough about stereochemistry to accurately confirm or dispute it.
– Carl Schildkraut
3 hours ago
@IvanNeretin My source for that claim was the first answer to this post on Quora. The reasoning seems OK to me, but I'm not knowledgeable enough about stereochemistry to accurately confirm or dispute it.
– Carl Schildkraut
3 hours ago
1
1
@IvanNeretin More precisely (as I suspect the questioner intended) compounds with no chiral centres can be chiral because of restricted rotation or other geometric features eg hexahelicene.
– matt_black
2 hours ago
@IvanNeretin More precisely (as I suspect the questioner intended) compounds with no chiral centres can be chiral because of restricted rotation or other geometric features eg hexahelicene.
– matt_black
2 hours ago
Depends on what you mean by "do they rotate?" What if they don't rotate light by a measurable amount? I'm sure I can contrive a number of compounds where that is the case.
– Zhe
2 hours ago
Depends on what you mean by "do they rotate?" What if they don't rotate light by a measurable amount? I'm sure I can contrive a number of compounds where that is the case.
– Zhe
2 hours ago
Compounds without chiral centers can be chiral all right.
– Ivan Neretin
2 hours ago
Compounds without chiral centers can be chiral all right.
– Ivan Neretin
2 hours ago
 |Â
show 2 more comments
1 Answer
1
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up vote
4
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Good question.
There's a phenomenon called cryptochirality (meaning “hidden chiralityâ€Â), when a compound, though chiral, has practically unmeasurable optical rotation activity.
It can happen to molecules with chiral center(s) bearing very similar substituents.
An example is 5-ethyl-5-propylundecane $ceCH3[CH2]5-C^*(CH2CH3)(CH2CH2CH3)-[CH2]3CH3$, don't call it “butyl(ethyl)hexyl(propyl)methaneâ€Â, found e.g. in beans. Its specific rotation is $[alpha] < 0.001$.[1]
(Related topic is chirality in polymers, see e.g. Q: Chirality on Carbon of PVC molecule.)
answered 46 mins ago
mykhal
2,9661747
Wow this answers a question I've mulled over for years! I had no idea there was a term for this. Thanks!
– Nicolau Saker Neto
19 mins ago
1
@NicolauSakerNeto, slightly off-topic, but you might also be interested to know that these cryptochiral molecules are capable of asymmetric induction in the Soai reaction. That's one of the few reactions we know (I think it might be the only one) where a tiny enantiomeric excess in the system (which could theoretically be just stochastic) can be propagated, leading to significant levels of enantioenrichment in the product, so it's somewhat relevant to the origin of homochirality.
– orthocresol♦
11 mins ago
(Well, the stated under-threshold optical rotation is for up to 580 nm, but specific rotation is measured for sodium D line 589 nm… but alkanes don't absorb in UV anyway, do they? Just let's not overcomplicate it.)
– mykhal
1 min ago
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
4
down vote
Good question.
There's a phenomenon called cryptochirality (meaning “hidden chiralityâ€Â), when a compound, though chiral, has practically unmeasurable optical rotation activity.
It can happen to molecules with chiral center(s) bearing very similar substituents.
An example is 5-ethyl-5-propylundecane $ceCH3[CH2]5-C^*(CH2CH3)(CH2CH2CH3)-[CH2]3CH3$, don't call it “butyl(ethyl)hexyl(propyl)methaneâ€Â, found e.g. in beans. Its specific rotation is $[alpha] < 0.001$.[1]
(Related topic is chirality in polymers, see e.g. Q: Chirality on Carbon of PVC molecule.)
answered 46 mins ago
mykhal
2,9661747
Wow this answers a question I've mulled over for years! I had no idea there was a term for this. Thanks!
– Nicolau Saker Neto
19 mins ago
1
@NicolauSakerNeto, slightly off-topic, but you might also be interested to know that these cryptochiral molecules are capable of asymmetric induction in the Soai reaction. That's one of the few reactions we know (I think it might be the only one) where a tiny enantiomeric excess in the system (which could theoretically be just stochastic) can be propagated, leading to significant levels of enantioenrichment in the product, so it's somewhat relevant to the origin of homochirality.
– orthocresol♦
11 mins ago
(Well, the stated under-threshold optical rotation is for up to 580 nm, but specific rotation is measured for sodium D line 589 nm… but alkanes don't absorb in UV anyway, do they? Just let's not overcomplicate it.)
– mykhal
1 min ago
add a comment |Â
up vote
4
down vote
Good question.
There's a phenomenon called cryptochirality (meaning “hidden chiralityâ€Â), when a compound, though chiral, has practically unmeasurable optical rotation activity.
It can happen to molecules with chiral center(s) bearing very similar substituents.
An example is 5-ethyl-5-propylundecane $ceCH3[CH2]5-C^*(CH2CH3)(CH2CH2CH3)-[CH2]3CH3$, don't call it “butyl(ethyl)hexyl(propyl)methaneâ€Â, found e.g. in beans. Its specific rotation is $[alpha] < 0.001$.[1]
(Related topic is chirality in polymers, see e.g. Q: Chirality on Carbon of PVC molecule.)
answered 46 mins ago
mykhal
2,9661747
Wow this answers a question I've mulled over for years! I had no idea there was a term for this. Thanks!
– Nicolau Saker Neto
19 mins ago
1
@NicolauSakerNeto, slightly off-topic, but you might also be interested to know that these cryptochiral molecules are capable of asymmetric induction in the Soai reaction. That's one of the few reactions we know (I think it might be the only one) where a tiny enantiomeric excess in the system (which could theoretically be just stochastic) can be propagated, leading to significant levels of enantioenrichment in the product, so it's somewhat relevant to the origin of homochirality.
– orthocresol♦
11 mins ago
(Well, the stated under-threshold optical rotation is for up to 580 nm, but specific rotation is measured for sodium D line 589 nm… but alkanes don't absorb in UV anyway, do they? Just let's not overcomplicate it.)
– mykhal
1 min ago
add a comment |Â
up vote
4
down vote
up vote
4
down vote
Good question.
There's a phenomenon called cryptochirality (meaning “hidden chiralityâ€Â), when a compound, though chiral, has practically unmeasurable optical rotation activity.
It can happen to molecules with chiral center(s) bearing very similar substituents.
An example is 5-ethyl-5-propylundecane $ceCH3[CH2]5-C^*(CH2CH3)(CH2CH2CH3)-[CH2]3CH3$, don't call it “butyl(ethyl)hexyl(propyl)methaneâ€Â, found e.g. in beans. Its specific rotation is $[alpha] < 0.001$.[1]
(Related topic is chirality in polymers, see e.g. Q: Chirality on Carbon of PVC molecule.)
answered 46 mins ago
mykhal
2,9661747
Good question.
There's a phenomenon called cryptochirality (meaning “hidden chiralityâ€Â), when a compound, though chiral, has practically unmeasurable optical rotation activity.
It can happen to molecules with chiral center(s) bearing very similar substituents.
An example is 5-ethyl-5-propylundecane $ceCH3[CH2]5-C^*(CH2CH3)(CH2CH2CH3)-[CH2]3CH3$, don't call it “butyl(ethyl)hexyl(propyl)methaneâ€Â, found e.g. in beans. Its specific rotation is $[alpha] < 0.001$.[1]
(Related topic is chirality in polymers, see e.g. Q: Chirality on Carbon of PVC molecule.)
answered 46 mins ago
mykhal
2,9661747
edited 9 mins ago
answered 46 mins ago
mykhal
2,9661747
answered 46 mins ago
mykhal
2,9661747
answered 46 mins ago
mykhal
2,9661747
2,9661747
Wow this answers a question I've mulled over for years! I had no idea there was a term for this. Thanks!
– Nicolau Saker Neto
19 mins ago
1
@NicolauSakerNeto, slightly off-topic, but you might also be interested to know that these cryptochiral molecules are capable of asymmetric induction in the Soai reaction. That's one of the few reactions we know (I think it might be the only one) where a tiny enantiomeric excess in the system (which could theoretically be just stochastic) can be propagated, leading to significant levels of enantioenrichment in the product, so it's somewhat relevant to the origin of homochirality.
– orthocresol♦
11 mins ago
(Well, the stated under-threshold optical rotation is for up to 580 nm, but specific rotation is measured for sodium D line 589 nm… but alkanes don't absorb in UV anyway, do they? Just let's not overcomplicate it.)
– mykhal
1 min ago
add a comment |Â
Wow this answers a question I've mulled over for years! I had no idea there was a term for this. Thanks!
– Nicolau Saker Neto
19 mins ago
1
@NicolauSakerNeto, slightly off-topic, but you might also be interested to know that these cryptochiral molecules are capable of asymmetric induction in the Soai reaction. That's one of the few reactions we know (I think it might be the only one) where a tiny enantiomeric excess in the system (which could theoretically be just stochastic) can be propagated, leading to significant levels of enantioenrichment in the product, so it's somewhat relevant to the origin of homochirality.
– orthocresol♦
11 mins ago
(Well, the stated under-threshold optical rotation is for up to 580 nm, but specific rotation is measured for sodium D line 589 nm… but alkanes don't absorb in UV anyway, do they? Just let's not overcomplicate it.)
– mykhal
1 min ago
Wow this answers a question I've mulled over for years! I had no idea there was a term for this. Thanks!
– Nicolau Saker Neto
19 mins ago
Wow this answers a question I've mulled over for years! I had no idea there was a term for this. Thanks!
– Nicolau Saker Neto
19 mins ago
1
1
@NicolauSakerNeto, slightly off-topic, but you might also be interested to know that these cryptochiral molecules are capable of asymmetric induction in the Soai reaction. That's one of the few reactions we know (I think it might be the only one) where a tiny enantiomeric excess in the system (which could theoretically be just stochastic) can be propagated, leading to significant levels of enantioenrichment in the product, so it's somewhat relevant to the origin of homochirality.
– orthocresol♦
11 mins ago
@NicolauSakerNeto, slightly off-topic, but you might also be interested to know that these cryptochiral molecules are capable of asymmetric induction in the Soai reaction. That's one of the few reactions we know (I think it might be the only one) where a tiny enantiomeric excess in the system (which could theoretically be just stochastic) can be propagated, leading to significant levels of enantioenrichment in the product, so it's somewhat relevant to the origin of homochirality.
– orthocresol♦
11 mins ago
(Well, the stated under-threshold optical rotation is for up to 580 nm, but specific rotation is measured for sodium D line 589 nm… but alkanes don't absorb in UV anyway, do they? Just let's not overcomplicate it.)
– mykhal
1 min ago
(Well, the stated under-threshold optical rotation is for up to 580 nm, but specific rotation is measured for sodium D line 589 nm… but alkanes don't absorb in UV anyway, do they? Just let's not overcomplicate it.)
– mykhal
1 min ago
add a comment |Â
Carl Schildkraut is a new contributor. Be nice, and check out our Code of Conduct.
Carl Schildkraut is a new contributor. Be nice, and check out our Code of Conduct.
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Achiral compounds don't rotate light.
– Ivan Neretin
3 hours ago
@IvanNeretin My source for that claim was the first answer to this post on Quora. The reasoning seems OK to me, but I'm not knowledgeable enough about stereochemistry to accurately confirm or dispute it.
– Carl Schildkraut
3 hours ago
1
@IvanNeretin More precisely (as I suspect the questioner intended) compounds with no chiral centres can be chiral because of restricted rotation or other geometric features eg hexahelicene.
– matt_black
2 hours ago
Depends on what you mean by "do they rotate?" What if they don't rotate light by a measurable amount? I'm sure I can contrive a number of compounds where that is the case.
– Zhe
2 hours ago
Compounds without chiral centers can be chiral all right.
– Ivan Neretin
2 hours ago