Numbering the Carbon

[JukaKim_1D]

How do you know which Carbon is carbon one, for example on 1-ethoxy-3-methylpentane? why is the carbon to the left of the oxygen 1 and not the one on the right? also, if the carbon to the left of the oxygen is the first carbon, why is the carbon to the right also a 1 when naming it "1-ethoxy"?

[Chem_Mod]

Because the other option is 5-ethoxy-3-methylpentane which uses higher numbers.

[Manuel Gonzalez_1L]

What I do is, I right them out both ways and then I add the number of Carbons and chose the one with the least. For example, 1+3 is 4 while 5+3 is 8. So the first one was the correct one because 4 is smaller than 8. Hopefully that helps a little.

[Johnchou1A]

What I do is, I right them out both ways and then I add the number of Carbons and chose the one with the least. For example, 1+3 is 4 while 5+3 is 8. So the first one was the correct one because 4 is smaller than 8. Hopefully that helps a little.

I thought that we aren't supposed to use the "sum rule" to decide numbering.

[Chem_Mod]

Do not EVER take the sum of numbers.

1,3 is preferable to 3,5 for the following reason: 1 is less than 3 (and that's it. If the first numbers were tied, then you move on to compare the second ones)

Taking the sum CAN result in the wrong name.