Rule A-2. Saturated Branched-chain Compounds and Univalent Radicals

2.1 - A saturated branched acyclic hydrocarbon is named by prefixing the designations of the side chains to the name of the longest chain present in the formula.

Example to Rule A-2.1

The following names are retained for unsubstituted hydrocarbons only:

Isobutane
Isopentane
Neopentane
Isohexane

2.2 - The longest chain is numbered from one end to the other by Arabic numerals, the direction being so chosen as to give the lowest numbers possible to the side chains. When series of locants containing the same number of terms are compared term by term, that series is "lowest" which contains the lowest number on the occasion of the first difference. This principle is applied irrespective of the nature of the substituents.

Examples to Rule A-2.2

2.25 - Univalent branched radicals derived from alkanes are named by prefixing the designation of the side chains to the name of the unbranched alkyl radical possessing the longest possible chain starting from the carbon atom with the free valence, the said atom being numbered as 1.

Examples to Rule A-2.25

1-Methylpentyl
2-Methylpentyl
5-Methylhexyl

The following names may be used for the unsubstituted radicals only:

Isopropyl
Isobutyl
sec-Butyl
tert-Butyl
Isopentyl
Neopentyl
tert-Pentyl
Isohexyl

2.3 - If two or more side chains of different nature are present, they are cited in alphabetical order .
The alphabetical order is decided as follows:
(i) The names of simple radicals are first alphabetized and the multiplying prefixes are then inserted.

Examples to Rule A-2.3(i)

ethyl is cited before methyl,
thus 4-Ethyl-3,3-dimethylheptane

(ii) The name of a complex radical is considered to begin with the first letter of its complete name.

Examples to Rule A-2.3(ii)

dimethylpentyl (as complete single substituent) is alphabetized under "d",
thus 7-(1,2-Dimethylpentyl)-5-ethyltridecane

(iii) In cases where names of complex radicals are composed of identical words, priority for citation is given to that radical which contains the lowest locant at the first cited point of difference in the radical.

Examples to Rule A-2.3(iii)

2.4 - If two or more side chains are in equivalent positions, the one to be assigned the lower number is that cited first in the name.

Examples: to Rule A-2.4

2.5 - The presence of identical unsubstituted radicals is indicated by the appropriate multiplying prefix di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-, deca-, undeca, etc.

Example to Rule A-2.5(a)

The presence of identical radicals each substituted in the same way may be indicated by the appropriate multiplying prefix bis-, tris-, tetrakis-, pentakis-, etc. The complete expression denoting such a side chain may be enclosed in parentheses or the carbon atoms in side chains may be indicated by primed numbers.

Examples to Rule A-2.5(b)

(a) Use of parentheses and unprimed numbers:
5,5-Bis(1,1-dimethylpropyl)-2-methyldecane
(b) Use of primes:
5,5-Bis-1',1'-dimethylpropyl-2-methyldecane

(a) Use of parentheses and unprimed numbers:
7-(1,1-Dimethylbutyl)-7-(1,1-dimethylpentyl)tridecane
(b) Use of primes:
7-1',1'-Dimethylbutyl-7-1",1"-dimethylpentyltridecane

2.6 - If chains of equal length are competing for selection as main chain in a saturated branched acyclic hydrocarbon, then the choice goes in series to:
(a) The chain which has the greatest number of side chains.

Example to Rule A-2.6(a)

(b) The chain whose side chains have the lowest-numbered locants.

Example to Rule A-2.6(b)

(c) The chain having the greatest number of carbon atoms in the smaller side chains.

Example to Rule A-2.6(c) 

(d) The chain having the least branched side chains.

Example to Rule A-2.6(d)

 http://www.acdlabs.com/iupac/nomenclature/79/r79_36.htm

Rule A-1. Saturated Unbranched-chain Compounds and Univalent Radicals

Rule A-1. Saturated Unbranched-chain Compounds and Univalent Radicals 

1.1 - The first four saturated unbranched acyclic hydrocarbons are called methane, ethane, propane and butane. Names of the higher members of this series consist of a numerical term, followed by "-ane" with elision of terminal "a" from the numerical term. Examples of these names are shown in the table below. The generic name of saturated acyclic hydrocarbons (branched or unbranched) is "alkane".
Examples of names:
(n = total number of carbon atoms)

n	n
1 Methane	22 Docosane
2 Ethane	23 Tricosane
3 Propane	24 Tetracosane
4 Butane	25 Pentacosane
5 Pentane	26 Hexacosane
6 Hexane	27 Heptacosane
7 Heptane	28 Octacosane
8 Octane	29 Nonacosane
9 Nonane	30 Triacontane
10 Decane	31 Hentriacontane
11 Undecane	32 Dotriacontane
12 Dodecane	33 Tritriacontane
13 Tridecane	40 Tetracontane
14 Tetradecane	50 Pentacontane
15 Pentadecane	60 Hexacontane
16 Hexadecane	70 Heptacontane
17 Heptadecane	80 Octacontane
18 Octadecane	90 Nonacontane
19 Nonadecane	100 Hectane
20 Icosane	132 Dotriacontahectane
21 Henicosane

1.2 - Univalent radicals derived from saturated unbranched acyclic hydrocarbons by removal of hydrogen from a terminal carbon atom are named by replacing the ending "-ane" of the name of the hydrocarbon by "-yl". The carbon atom with the free valence is numbered as 1. As a class, these radicals are called normal, or unbranched chain, alkyls.

Examples to Rule A-1.2

http://www.acdlabs.com/iupac/nomenclature/79/r79_34.htm

ACS article on Medicinal Chemistry

Medicinal Chemistry

Has a History

Medicinal chemistry is the application of chemical research techniques to the synthesis of pharmaceuticals. During the early stages of medicinal chemistry development, scientists were primarily concerned with the isolation of medicinal agents found in plants. Today, scientists in this field are also equally concerned with the creation of new synthetic drug compounds. Medicinal chemistry is almost always geared toward drug discovery and development.

Is Carrying Out Basic Research

Medicinal chemistry research is an important area of research that is performed in many university labs. As an assistant professor at the University of Maryland School of Pharmacy, Alex Mackerell, Jr. has done research on cocaine and cocaine analogs to develop drugs for the treatment of cocaine addiction. His research, however, was not solely focused on just getting a product, but also on understanding basic chemical reactions and their properties. "We were interested in the physical properties and in the underlying mechanisms of cocaine," he says. The purpose of the research was to develop a cocaine antagonist that would cause ill effects when cocaine is ingested. This type of research characterizes the research being conducted in academic environments.

Can Lead To Treatment of Diseases

Grace Lee is using her bachelor's degree in pharmaceutical chemistry for a different kind of drug development. She is a part of a team of analytical chemists at the National Institute of Health (NIH) who formulate drugs that could be used to treat patients with very rare diseases. These formulations are called orphan drugs because they are used to treat diseases found in only small portions of the population. "We try to develop a treatment either from scratch or from research that has already been done in other countries," she says. "My job is challenging because it requires working with several different compounds at one time." Everyday she relies on her knowledge from her undergraduate courses in analytical and organic chemistry. She uses this basic chemistry training when testing and retesting compounds for safety and efficacy, which is the measure of how well a drug product works in the human body.

Is Developing Guidelines

Chemists as the U.S. Food and Drug Administration (FDA) review new drug applications from pharmaceutical companies and are also responsible for reviewing the processes by which the substances are made. These chemists do not work in a laboratory, but their role in medicinal chemistry is important. Charles Kumkumian is the assistant director of the Office of Drug Evaluation for the FDA that, he says, is the largest regulatory group in the world, employing more than 9,000 people. He says that there are about 900 chemists employed in various functions throughout FDA. Ten percent of these are chemists who review new drug applications for entirely new therapeutic entities. An equal number of chemists review additional new drug applications that are generic formulas or over-the-counter dosages.

Links Many Scientific Disciplines

The focus on development of new synthetic drug compounds has resulted in the incorporation of many other disciplines, such as biochemistry and molecular biology, into medicinal chemistry. "Medicinal chemistry involves working in teams with scientists from a variety of other disciplines," says James Kaminski, a senior principal scientist at Schering Plough. "There is a lot of collaboration between chemists and biologists while searching for a lead on a new drug or doing research on a preclinical drug candidate. Then, when you look into the drug safety profile, you work with toxicologists and pharmacologists."

Joel Barrish, group/project leader in pharmaceutical and drug discovery research at Bristol-Myers Squibb, says that most of his time is spent coordinating the synthetic chemistry efforts of chemists in his group with other members of the project working group outside of chemistry. These areas include biology, computer-aided design, x-ray crystallography, metabolism and pharmacokinetics, legal and regulatory affairs, clinical, franchise management, pharmaceutics, and process research chemistry. Barrish says, "Working in teams is essential to discovering drugs because many different aspects of a molecule must be defined to identify a candidate for clinical studies." He adds, "Medicinal chemistry is the drug discovery engine that provides the tools for the rest of the organization so they can determine the importance of particular biological targets. Kaminski also believes that understanding and interacting with other scientists is key to being successful in this area. Most medicinal chemists find that the opportunity to do research with other scientists while helping to new drugs is an exciting part of their work. Barrish says, "Drug discovery research is a highly creative and stimulating work environment where people are driven to succeed by personal and scientific objectives, and the desire to contribute to society's well-being.

Work Description

Medicinal chemists apply their chemistry training to the process of synthesizing new pharmaceuticals. They also work on improving the process by which other pharmaceuticals are made. Most chemists work with a team of scientists from different disciplines, including biologists, toxicologists, pharmacologists, theoretical chemists, microbiologists, and biopharmacists. Together this team uses sophisticated analytical techniques to synthesize and test new drug products and to develop the most cost-effective and environmentally friendly means of production.

Work Conditions

Medicinal chemistry offers a variety of lab opportunities. Most chemists use their research skills to formulate, produce, and analyze new compounds. However, each lab environment is unique–daily activities and career opportunities differ with each one. In academia, chemists explore a compound's different mechanisms in basic research as well as teach at least one full course. In government, laboratory work is not always required, especially at the FDA where they review drug applications. Industry, on other hand, offers chemists a choice of moving into management or staying in the lab.

Places of Employment

Though a wide array of positions exist for chemists in medicinal chemistry, the availability of these jobs is dependent upon the economy, shifting government regulations, and research grants. Employment prospects include the academic environment, pharmaceutical companies, and government. Biotechnology organizations also employ chemists in this area. Industry provides the opportunity to choose between a traditional laboratory career or a non laboratory chemistry career in management. Government also offers a choice between a laboratory position and a nonlaboratory chemistry position, such as drug application review.

Personal Characteristics

Medicinal chemists must enjoy varied activities and must be receptive to exploring the unknown. A good imagination and persistence are also two important qualities to have when considering a career in medicinal chemistry. Being a team player with good writing and verbal communication skills are invaluable assets when interacting with scientists from other disciplines.

Education and Training

Generally, pharmaceutical companies hire only people with research experience, advanced degrees especially in organic chemistry, and at least two years of post-doctoral experience. Most chemists in traditional research careers are Ph.D. chemists while chemists with B.S. degrees generally serve as research technicians. You can place yourself in a competitive position by getting as much experience as possible with a strong background in organic chemistry and biochemistry. A number of universities have formed medicinal chemistry programs in the past 20 years.

Salary Information

To find out what a person in this type of position earns in your area of the country, please refer to the ACS Salary Comparator. Use of the ACS Salary Comparator is a member-only benefit. General information about salaries in chemical professions can be obtained through published survey results.

Job Outlook

Because of the ever-changing economy and government health care reform regulations, the job outlook for medicinal chemists in today's market is mixed. Many changes are taking place within the pharmaceutical industry. Companies have been decreasing the size of their research labs or merging with other companies. Therefore, the job outlook is somewhat uncertain for medicinal chemists. While industry is downsizing, some government agencies are looking for chemists to fill nonlaboratory chemistry positions. An excess of jobs is not available in academia either. Some chemists are optimistic that this downturn is only cyclical as much research remains to be done.

For More Information

American Association of Pharmaceutical Scientists
1650 King Street, 2nd Floor
Alexandria, VA 22314-3105
(703) 548.3000

What You Can Do Now

Undergraduate students should maintain a high degree of scholarship and get as much experience as possible. Internships provide valuable experience and are the best way to see if a career in medicinal chemistry in a pharmaceutical lab appeals to you. Undergraduate research in university laboratories is another way to gain experience and as well as become familiar with the day-to-day activities in academia. Chemists advise undergraduate students to get a strong background in the basic chemistry courses and, if a research position in this areas is desired, continue on to get an advanced degree.

http://www.acs.org/content/acs/en/careers/whatchemistsdo/careers/medicinal-chemistry.html