Isomers drawing

The butylene isomers shown in Figure 1—10 add another degree of complexity because of the double bond. It is an easy mistake to go overboard in drawing isomers that have the same formula but appear to look different. But be careful, because molecules don t know left from right or front from back. What may look different on paper may be identical when rolled over in space. That s why the isobutylene in Figure 1—10 is drawn the way it is. If you try to attach that =CH2 group to some other carbon in the molecule, the whole thing becomes a normal butylene. 

The task of drawing isomers for a particular formula can be made easier by comparing the number of hydrogens with the number of carbons in the formula. Such a comparison allows the calculation of the degree of unsaturation, which furnishes useful information about possible structures that will fit the formula (such as whether double bonds can be present) and provides a starting point for drawing isomers. 

The DU is very useful when drawing isomers. Let s look at a simple example. Suppose we are asked to draw the constitutional isomers with the formula C5H 0- The DU for C5H o is [(2(5) + 2) — 10]/2 = 1. Therefore, this compound must have one double bond or one ring. Any compound that has five C s and one double bond or one ring will fit the formula. Although C5H 2 has only three isomers, having two fewer H s actually increases the number of isomers, because there is now a double bond or a ring to vary. 

Draw isomers of alkanes and cycloalkanes, and use the IUPAC rules to name alkanes, cycloalkanes, and bicyclic alkanes. Problems 3-32,33,37, and 41... 

The rules and procedures for drawing structural isomers are the same used for drawing electron dot formulas. Every atom in the molecular formula must be used and each atom must have its valence satisfied. To draw a structure, bond all atoms with a valence greater than one with single bonds. Attach monovalent atoms to the polyvalent ones until all valences have been satisfied. If there are insufficient monovalent atoms in the formula to accomplish this, insert double bonds, triple bonds or draw cyclic structures until it is possible to satisfy all valences. To draw isomers, vary the arrangements of atoms and bonds to form different molecules. 

Now draw isomers with six carbons in the longest chain and vary the position of the one-carbon chain. 

Finally, draw isomers in which the bromines are on the middle two carbons and the two carbons on the other end. 

Drawing isomers requires finding a system that allows you to consider all the possible perturbations. One approach is to start with the longest possible chain and then reduce the chain length one carbon at a time, considering the possible locations of the displaced methyl group with each reduction. 

Drawing Isomers for Compounds with Two Double Bonds... 

B. Dc.war benzene (2) exists as cis and tram isomers. Draw struetures of the two f onris. construct the appropriate input files and determine the c.is-iram isomerization energy of (2). 

Identify the relationship in each of the following pairs Do the drawings represent consti jv. tutional isomers or stereoisomers or are they just different ways of drawing the same compound" )... 

How many isomers of CsHs can you write" An article in the March 1994 issue of the Journal of Chemical Educa tion (pp 222-224) claims that there are several hun dred and draws structural formulas for 25 of them... 

With the five-carbon alkane, pentane, there are three ways to draw the structural formula of this compound with five carbon atoms and twelve hydrogen atoms. The isomers of normal pentane are isopentane and neopentane. The structural formulas of these compounds are illustrated in Table 2, while typical properties are given in Table 1. 

Draw Haworth structures for the two possible isomers of D-altrose (Figure 7.2) and D-psicose (Figure 7.3). 

Draw the structures of (a) all the possible triacylglycerols that can be formed from glycerol with stearic and arachidonic acid, and (b) all the phosphatidylserine isomers that can be formed from palmitic and linolenic acids. 

The molecule below has four stereoisomeric forms exoO exoCH2Br, exoO endoCH2Br, and so on. Examine electrostatic potential maps of the four ions and identify the most nucleophilic (electron-rich) atom in each. Examine the electron-acceptor orbital (the lowest-unoccuped molecular orbital or LUMO) in each and identify electrophilic sites that are in close proximity to the nucleophilic. Which isomers can undergo an intramolecular E2 reaction Draw the expected 8 2 and E2 products. Which isomers should not readily undergo intramolecular reactions Why are these inert ... 

In order to predict the structure of the product, you must identify the factors that will tend to favor selective ketal formation. Consider selective carbonyl protonation first. Obtain energies and atomic charges, and display electrostatic potential maps of the alternative protonated ketones (protonated ketone A, protonated ketone B). Identify the more stable isomer. Compare geometries and draw whatever Lewis structures are needed to account for your data. Why is one isomer more stable than the other Is the more stable isomer also that in which the positive charge is better delocalized Will the more stable isomer undergo nucleophilic attack more or less easily than the other Explain. 

Consider 1,3-pentadiene and 1,4-pentadiene. Which, if either, would benefit from the type of resonance described above Draw appropriate resonance contributors for this isomer. Indicate the likely importance of different zwitterionic structures which you might draw. Compare the energies of 1,3-pentadiene and 1,4-pentadiene. Which one is more stable ... 

Dithiiranethione is an isomer of CS3 and its preparation and structure have been drawing much attention [75JCS(P2)559]. In the chemiionization process of CS + CS2 using the molecular beam photoionrzation method, the photoionization efficiency curve of CS3 was observed (80JCP4242). 

The distributions of phenolic isomers in hydroxylations in the animal body arc often similar to those obtained by Fenton s reagent. For example, the hydroxylation of coumarin by the rabbit gives the six hydroxycoumarins in amounts decreasing in the order 3- >7->6- >8- >4- /—5-, whereas Fenton s reagent gives mainly the 3-, 5-, and 7-derivatives with traces of the 6- and 8-derivatives. It may, however, be misleading to draw conclusions about the nature of... 

Thomson 1 v.r Click Organic Interactive to learn to draw and recognize alkane Isomers. 

Draw the eight 5-carbon alkyl groups (pentyl isomers). 

There are seven constitutional isomers with the formula C4H qO. Draw as many as you can. 

For each of the following compounds, draw an isomer that has the same functional groups. Each intersection of lines represents a carbon atom with the appropriate number of hydrogens attached. 

There are four cis-trans isomers of menthol (Problem 4.3/), including the one shown. Draw the other three. 

A wyo-Inositol, one of the isomers of 1,2,3,4,5,6-hexahydroxycyclohexane, acts as a growth factor in both animals and microorganisms. Draw the most stable chair conformation of myo-inositol. 

How many cis-trans stereoisomers of ///yo-inositol (Problem 4.49) are there Draw the structure of the most stable isomer. 

Ketones react with alcohols to yield products called acetals. Why does the all-cis isomer of 4- cvf-butyl-l13-cyclohexanediol react readily with acetone and an acid cataty st to form an acetal while other stereoisomers do not react In formulating your answer, draw the more stable chair conformations of all four stereoisomers and the product acetal. Use molecular models for help. 

Which of the following compounds can exist as pairs of cis-trans isnmers Draw each cis-trans pair, and indicate the geometry of each isomer. 

Draw and name the 6 pentene isomers, C5HK3, including ,Z isomers. 

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