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Accessible Content in Chemistry

Chemistry Examples

Example 1

A graph shows the H N M R spectrum of a polyisopropene sample for different p p m values.
Caption

1H NMR spectrum of a polyisoprene sample, discussed in Example 1.7. (Data courtesy of N. Lynd and M.A. Hillmyer.)

Alt Text

A graph shows the H N M R spectrum of a polyisopropene sample for different p p m values.

Long Description

The horizontal axis is labeled p p m and ranges from 6 to 0, in increments of 1. The graph shows a skeletal structure consisting of a chain of 11 carbon atoms. The carbon group in the first position, labeled C H 2 superscript c, is bonded to a hydroxyl group. The carbon atom in the third position is bonded to the central atom of an isopropene group. The carbon group at the end of the double bond is labeled C H 2 superscript b. A double bond exists between the carbon atoms in the sixth and seventh positions. The hydrogen atom bonded to the carbon in the seventh position is labeled H superscript a. The carbon group in the eleventh position is labeled C H 3 superscript d. The carbon atom in the tenth position is bonded to an ethyl group, whose terminal carbon group is labeled C H 3 superscript d. A pair of parentheses enclosing the third and fourth carbon atoms is labeled n. A pair of parentheses enclosing the fifth, sixth, seventh, and eighth carbon atoms is labeled m. The peaks at different p p m values in the decreasing order of height are as follows: p p m equals 1.6, p p m equals 1.4, p p m equals 2, p p m equals 5.1, labeled a, p p m equals 0.8, labeled d, p p m equals 4.8, labeled b, and p p m equals 3.6, labeled c.

Example 2

A triangular relationship between experimental quantities and the rate constants derived from them.
Caption

Schematic relationship among the various experimental quantities (Rp, Nn, and τ) and the rate constants kd, kp, and kt derived therefrom.

Alt Text

A triangular relationship between experimental quantities and the rate constants derived from them.

Long Description

"The details of this schematic relationship between R subscript p (lower left), N subscript n (lower right), tau bar (top). The following are in the three points in the triangle: (a) R subscript p: K subscript p open parenthesis k subscript d over k subscript t close parenthesis to the power 1 over 2. (b) N subscript n: fraction: numerator: K subscript p; denominator: open parenthesis K, subscript t K subscript d close parenthesis to the power 1 over 2 end fraction. (c) Tau bar: fraction: numerator: 1; denominator: open parenthesis K subscript t, K subscript d close parenthesis to the power 1 over 2 end fraction.The following formulas are on the lines between the points: (1) Between R subscript p and Tau bar: R subscript p tau bar equals k subscript p slash k subscript. (2) Between N subscript n and Tau bar: N subscript n equals tau bar, k subscript p. 93) Between R subscript p and N subscript n: R subscript p and N subscript n equals K subscript p squared slash k subscript t. Inside this triangle is another connection which is as follows: The box k subscript t is in the middle of the triangle on the inside. Connections are between k subscript t, R subscript p, and N subscript n. From K subscript t, lines go to the connections between R subscript p and Tau bar and N subscript n and tau bar. (d) Between R subscript p and N subscript n: R subscript p equals k subscript d, N subscript n. (e) Between R subscript p and k subscript t: K subscript p over k subscript t to the power 1 over 2. (f) Between N subscript n and k subscript t: K subscript p over k subscript t to the power 1 over 2. (g) From the box R subscript p equals k subscript d, N subscript n, lines go to the connections between R subscript p and k subscript t and N subscript n and k subscript t."

Example 3

The molecular structure of physostigmine, represented in line and wedge notation.
Alt Text

The molecular structure of physostigmine, represented in line and wedge notation.

Long Description

The two dimensional molecular structure of physostigmine is comprised s of linear and closed ring carbon units. The molecule has the following chain sequence: H 3 C, single bond, N, single bond, C, single bond, O, single bond, tricyclic closed ring structure. The N is also single bonded to an H in side chain. The C atom between N and O is also double bonded to an O atom. The tricyclic closed ring structure includes a six-membered benzene ring attached to a five-member ring with N. This ring is further attached to a similar five-member ring with N. The six-membered benzene ring is attached to the first five-membered ring at atoms C 3 and C 4. The two five-membered rings are connected at atoms C 1 and C 2. The N of both rings are single bonded to a methyl or C H 3 group. The common C 1 of both rings are wedge bonded to an H atom, while the common C 2 of both rings are wedge bonded to a methyl or C H 3 group.