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Jan
Jan
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DMSO and acetone have almost identical structures, except for us replacing the carbonyl carbon with sulfur to obtain DMSO. DMSO's melting point is 19 °C$19~\mathrm{^\circ C}$, whereas acetone's is -95 °C$-95\ \mathrm{^\circ C}$.

Is the dominant factor DMSO's larger molecular weight? Probably not. While acetone is 58 g/mol$58\ \mathrm{g/mol}$ vs. DMSO's 78 g/mol$78\ \mathrm{g/mol}$, 2-pentanone is 86 g/mol$86\ \mathrm{g/mol}$, but still has a very low melting temperature of -77 °C$-77\ \mathrm{^\circ C}$.

The only protons on all of these species are aliphatic, so hydrogen bonding is probably not the dominant contributor to this effect either.

What's going on?!

DMSO and acetone have almost identical structures, except for us replacing the carbonyl carbon with sulfur to obtain DMSO. DMSO's melting point is 19 °C, whereas acetone's is -95 °C.

Is the dominant factor DMSO's larger molecular weight? Probably not. While acetone is 58 g/mol vs. DMSO's 78 g/mol, 2-pentanone is 86 g/mol, but still has a very low melting temperature of -77 °C.

The only protons on all of these species are aliphatic, so hydrogen bonding is probably not the dominant contributor to this effect either.

What's going on?!

DMSO and acetone have almost identical structures, except for us replacing the carbonyl carbon with sulfur to obtain DMSO. DMSO's melting point is $19~\mathrm{^\circ C}$, whereas acetone's is $-95\ \mathrm{^\circ C}$.

Is the dominant factor DMSO's larger molecular weight? Probably not. While acetone is $58\ \mathrm{g/mol}$ vs. DMSO's $78\ \mathrm{g/mol}$, 2-pentanone is $86\ \mathrm{g/mol}$, but still has a very low melting temperature of $-77\ \mathrm{^\circ C}$.

The only protons on all of these species are aliphatic, so hydrogen bonding is probably not the dominant contributor to this effect either.

What's going on?

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Klaus-Dieter Warzecha
Klaus-Dieter Warzecha
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DMSO and acetone have almost identical structures, except for us replacing the carbonyl carbon with sulfur to obtain DMSO. DMSO's melting point is 19 oC°C, whereas acetone's is -95 oC°C.

Is the dominant factor DMSO's larger molecular weight? Probably not. While acetone is 58 g/mol vs. DMSO's 78 g/mol, 2-pentanone is 86 g/mol, but still has a very low melting temperature of -77 oC°C.

The only protons on all of these species are aliphatic, so hydrogen bonding is probably not the dominant contributor to this effect either.

What's going on?!

DMSO and acetone have almost identical structures, except for us replacing the carbonyl carbon with sulfur to obtain DMSO. DMSO's melting point is 19 oC, whereas acetone's is -95 oC.

Is the dominant factor DMSO's larger molecular weight? Probably not. While acetone is 58 g/mol vs. DMSO's 78 g/mol, 2-pentanone is 86 g/mol, but still has a very low melting temperature of -77 oC.

The only protons on all of these species are aliphatic, so hydrogen bonding is probably not the dominant contributor to this effect either.

What's going on?!

DMSO and acetone have almost identical structures, except for us replacing the carbonyl carbon with sulfur to obtain DMSO. DMSO's melting point is 19 °C, whereas acetone's is -95 °C.

Is the dominant factor DMSO's larger molecular weight? Probably not. While acetone is 58 g/mol vs. DMSO's 78 g/mol, 2-pentanone is 86 g/mol, but still has a very low melting temperature of -77 °C.

The only protons on all of these species are aliphatic, so hydrogen bonding is probably not the dominant contributor to this effect either.

What's going on?!

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user49404
user49404
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Why do DMSO and acetone have such radically different melting temperatures?

DMSO and acetone have almost identical structures, except for us replacing the carbonyl carbon with sulfur to obtain DMSO. DMSO's melting point is 19 oC, whereas acetone's is -95 oC.

Is the dominant factor DMSO's larger molecular weight? Probably not. While acetone is 58 g/mol vs. DMSO's 78 g/mol, 2-pentanone is 86 g/mol, but still has a very low melting temperature of -77 oC.

The only protons on all of these species are aliphatic, so hydrogen bonding is probably not the dominant contributor to this effect either.

What's going on?!