Identifying Cyclic Alkanes: C6H12 - C9H18 - C10H20

[312213]

Homework Statement

Name each of the following cyclic alkanes, and indicate the formula of the compound.
http://img230.imageshack.us/img230/1042/organicnaming.jpg

Homework Equations

The Attempt at a Solution

a. The rectangle has four corners so four carbon for butane. The branch off has two carbons so eth-. Numbering the branch C as 1, the naming is 1-ethylcyclobutane with C₆H₁₂ because each corner is 1 C plus the C written and the H comes from subtracting 4 with the number of bonds connected to each of the C. Is this correct?

b. The pentagon has five corners so five corner for pentane. The branch off is prop- and meth-. Naming starts with alphabetical order so meth- first so the prop- is three. 1-methyl-3-propylcyclopentane. Logic from a., C₉H₁₈. Is this correct?

c. Hexane from six corners. Dimethyl and ethyl here. Is this named 1-ethyl-2,6-dimethylcyclohexane or 2-ethyl-1,3-dimethylcyclohexane? C₁₀H₂₀.

If there is a mistake, which part?

 

[Mtnbiker]

Homework Statement

Name each of the following cyclic alkanes, and indicate the formula of the compound.
http://img230.imageshack.us/img230/1042/organicnaming.jpg

Homework Equations

The Attempt at a Solution

a. The rectangle has four corners so four carbon for butane. The branch off has two carbons so eth-. Numbering the branch C as 1, the naming is 1-ethylcyclobutane with C₆H₁₂ because each corner is 1 C plus the C written and the H comes from subtracting 4 with the number of bonds connected to each of the C. Is this correct?

b. The pentagon has five corners so five corner for pentane. The branch off is prop- and meth-. Naming starts with alphabetical order so meth- first so the prop- is three. 1-methyl-3-propylcyclopentane. Logic from a., C₉H₁₈. Is this correct?

c. Hexane from six corners. Dimethyl and ethyl here. Is this named 1-ethyl-2,6-dimethylcyclohexane or 2-ethyl-1,3-dimethylcyclohexane? C₁₀H₂₀.

If there is a mistake, which part?

A is just ethylcyclobutane. There is no need to number the substituent, since a cycloalkane with 1 substituent will always have it at the #1 carbon. You had the formula right.

B is correct.

C is 2-ethyl-1,3-dimethylcyclohexane (you number so as to give your substituents the lowest number possible, in the absence of priority substituents such as OH). Formula is correct.

 

[Blueshift5]

it is important to follow the IUPAC (International Union of Pure and Applied Chemistry) naming conventions for organic compounds. According to these conventions, the first step in naming a cyclic alkane is to identify the parent chain, which is the longest continuous chain of carbon atoms in the molecule. In all three compounds given, the parent chain is a ring of carbon atoms, so the suffix "-cyclo" is added to the name.

a. The first compound is correct. The parent chain is a four-carbon ring, so it is named cyclobutane. The branch off the ring is an ethyl group, so the full name is 1-ethylcyclobutane. The formula C6H12 is correct, as there are four carbons in the ring and two in the ethyl group, making a total of six carbon atoms.

b. The second compound is not named correctly. The parent chain is a five-carbon ring, so it is named cyclopentane. The branch off the ring is a methyl group and a propyl group, so the full name is 1-methyl-3-propylcyclopentane. The formula C9H18 is correct, as there are five carbons in the ring, one in the methyl group, and three in the propyl group, making a total of nine carbon atoms.

c. The third compound is also not named correctly. The parent chain is a six-carbon ring, so it is named cyclohexane. The branch off the ring is two methyl groups and one ethyl group, so the full name is 1,3-dimethyl-2-ethylcyclohexane. The formula C10H20 is correct, as there are six carbons in the ring, four in the methyl groups, and two in the ethyl group, making a total of ten carbon atoms.

In general, when naming cyclic alkanes, the parent chain is numbered starting from any side of the ring that allows the substituents (branches) to have the lowest possible numbers. In cases where there are multiple substituents, the substituents are named in alphabetical order and their positions are indicated by numbers. It is important to note that the prefixes "di-", "tri-", etc. are used to indicate multiple copies of the same substituent, while the prefixes "iso-" and "neo-" are used to indicate different