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Topic: Leaving group


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In the News (Fri 19 Jul 19)

  
  Leaving group
A leaving group is an atom or molecule that detaches from an organic molecule[?], which after detachment, is called the residual or main part.
Leaving group affects the intrinsic reactivity, not the nucleophilic discrimination factors.
1 reactions, the leaving group anionizes and leaves.
www.ebroadcast.com.au /lookup/encyclopedia/le/Leaving_group.html   (124 words)

  
 Leaving group - Wikipedia, the free encyclopedia
Leaving groups affect the intrinsic reactivity, not the nucleophilic discrimination factors.
This is because the lower the pKa of the conjugate acid of the leaving group, the more it stays in its anion (l.g.'s may be neutral), leaving group, form.
The structure of the leaving group affects the rates of both Sn1 and Sn2 reactions.
en.wikipedia.org /wiki/Leaving_group   (390 words)

  
 group therapy
In an ongoing group, once the group starts, it continues indefinitely, with some group members completing treatment and leaving the group, and others joining along the way as openings are available in the group.
Group therapy is different from individual therapy in a number of ways, with the most obvious difference being the number of people in the room with the psychologist.
Group members are told not to discuss information shared in the group with others, and usually the need for mutual confidentiality preserves the privacy of the information.
www.psychologyinfo.com /treatment/group_therapy.html   (858 words)

  
 Sharing The Pain And The Promise In Group
Instruct the group that if someone wants to discuss an incident in which she vomited ten times, took diuretics, or went on the Stairmaster for two hours, she is to use the terms purged or exercised and is not to give any specifics about the means, the amount, or any other details.
When everyone in the group hates her body or when everyone purges, it is easy for the behavior to become somewhat "normalized." It is important that the group facilitator keep this in mind and somehow discuss this with the group.
Group members feeling judged or pressured may not attribute it to other group members and may feel it is their own inadequacy or weakness that is the problem.
www.webmd.com /content/Article/83/97757.htm?pagenumber=3   (1102 words)

  
 Defintion of leaving_group - Chemistry Dictionary
An atom or group (charged or uncharged) that becomes detached from an atom in what is considered to be the residual or main part of the substrate in a specified reaction.
the leaving group is NMe3; in the electrophilic nitration of benzene, it is H+.
The leaving group is not, in general, the same as the substituent group present in the substrate (e.g.
www.chemicool.com /definition/leaving_group.html   (158 words)

  
 Drawing Substitution and Elimination Products
Erase the bond between the electrophilic C atom and the leaving group, and create a new bond between the electrophilic C atom and the nucleophilic atom.
If the nucleophile and the leaving group are assigned the same priority with respect to the other substituents on the electrophilic C atom, the configuration will change from R to S or vice versa.
Erase the bond between the electrophilic C atom and the leaving group, erase the bond between a H atom and a C atom adjacent to the electrophilic C atom, and create a new π bond between the two aforementioned C atoms.
www.chem.uky.edu /courses/che232/RBG/handouts/drawSnE.HTML   (808 words)

  
 Re: Leaving Groups in Organic Chemistry
CH But the other factor is the strength of the group's bond to carbon--and it is an experimental fact that the strength of an atom's bond to carbon correlates well with the strength of its bond to hydrogen.
So again, the ability of something to act as a leaving group in a nucleophilic substitution or elimination reaction depends on its standalone stability as an anion, and on the strength of its bond to carbon--and both correlate well with its Brønsted basicity.
of less than about 25 is a good leaving group if the molecule bears a negative charge and can form a carbonyl group when the leaving group leaves.
www.madsci.org /posts/archives/feb2002/1014145631.Ch.r.html   (490 words)

  
 [No title]
The most important result of a leaving examination, according to Chrystal, is to set a minimum standard for the work of the secondary schools, and to mark, to some extent, the boundary between their level and that of the universities.
Chrystal's feasibility report of instituting a general leaving examination in mathematics, the report of higher class schools' examiner's as to its extension to other subjects, and the evidence laid before Parker's inquiry committee, all convinced Craik that the institution of a Leaving Certificate Examination was both desirable and practicable.
The Leaving Certificate instituted in 1888 was the supreme award in Scottish secondary education until its replacement by the Scottish Certificate of Education in 1962.
www-groups.dcs.st-and.ac.uk /~history/Education/scottishleaving.html   (2353 words)

  
 San Francisco Shamans: Information about leaving the Shamanic Groups
Long-term committed group members, as opposed to trial-members, would ideally give a notice of one month to indicate their intention to leave their respective group.
However if this is not possible, then we ask members who have decided to leave their group to inform their respective group, one week in advance if they decide to leave a group and attend a last meeting in which they and the other group members can complete and say their good-byes.
It is felt that a year of study and initiation opens gateways into the inner planes or temples for initiates and that they may utilize this access to the inner planes in their solo spiritual work when they leave the groups physically.
www.shamans-sf.org /info/leave.html   (313 words)

  
 Modified carbon products with leaving groups and inks and coatings containing modified carbon products - Patent 5895522
The leaving group is any group that may be eliminated from the organic group which is attached to the carbon colorant or pigment.
After the leaving group is eliminated from the organic group attached to the carbon product, the number of ionic or ionizable groups remaining attached to the carbon product is reduced.
The ionic group may be an anionic group or a cationic group and the ionizable group may form an anion or a cation.
www.freepatentsonline.com /5895522.html   (6248 words)

  
 Maternity Group Homes Classification and Literature Review: Research Related to Maternity Group Homes
Given the considerable interest in maternity group homes and the roles they can play in assisting pregnant and parenting teens transition to independence, it is important to document and synthesize what is known about these homes, as well as to identify gaps in the existing research.
A study of two maternity group homes in California found the clinical and psychological characteristics of residents to be similar to those of different populations of pregnant teens in other studies, although residents had lower self-esteem than older mothers in other studies, particularly on the school-academic subscale (Koniak 1989).
Since some teens leave because their need for the maternity group home has ended, and some homes are designed to provide only temporary housing, a short length of stay is not necessarily a negative outcome.
aspe.hhs.gov /search/hsp/grouphomes04/litreview04/ch3.htm   (5543 words)

  
 DLEG - Leaving an Employer Group   (Site not responding. Last check: 2007-10-12)
You leave the employer, the group policy has been discontinued for all employees or for a specific class of employees, you are involuntarily terminated for reasons other than gross misconduct.
COBRA is a federal law that gives you the right to continue in the group on a temporary basis after you (or your spouse or parent) leave an employer with 20 or more employees.
The group conversion policy must be issued with no pre-existing condition exclusions and cover all members of the family covered under the group plan.
www.michigan.gov /cis/0,1607,7-154-10555_12902_35510_35540---,00.html   (2618 words)

  
 (Unedited) Sample Chapter -- 431700G Group Psychotherapy for Women With Breast Cancer   (Site not responding. Last check: 2007-10-12)
Yet it is important to hold to the agreed-upon group structure, and to give the member and the group a chance to wind down and to integrate their feelings and thoughts.
In one group, in response to a question about what the women had been getting out of the group, Elizabeth stated that she was not here to get anything out of the group, but rather to let others know about God, and how God could cure them if they asked him to.
Yet with group support, seeing others tolerating these issues, and with the relaxation techniques training their mind to focus on comfortable sensations in the moment, the group may be the best anxiolytic available for them.
www.apa.org /books/431700Gs.html   (6848 words)

  
 Flickr: FlickrCentral
Groups on flickr are often simply a repository of similar themed photos.
Maybe if your average group wasn't spilling over with "dumped" pics and people were actually able to peruse a group without being overwhelmed we might actually get to see some good shots.
I'm all for it - I was in the process of trimming the number of groups I was in and found it annoying to have to manually delete each picture I posted in the group.
flickr.com /groups/central/discuss/72157594315070529   (533 words)

  
 .: Research - Richard Research Group :.   (Site not responding. Last check: 2007-10-12)
In the second step for the hydrolysis reaction, the residue that functions in catalysis of leaving group expulsion acts as a catalyst of the addition of water (ROH = HOH) to the glycosyl-enzyme intermediate.
In the case of b-galactosidase these binding interactions involve largely the protein and the β-D-galactopyranosyl group of substrate because this enzyme is an efficient catalysis of cleavage of alkyl β-D-galactopyranosides, where the leaving group is a small alkyl alcohol such as ethanol and trifluoroethanol.
The large fraction of this transition state stabilization that originates in some manner from interaction with a single C-2 hydroxyl group is striking, but poorly understood and is currently under investigation in our laboratory.
www.acsu.buffalo.edu /~jrichard/r_glycosyl_tx.html   (411 words)

  
 Molecular Mechanisms Group
The Group was site-visited in June 1996 and a new quinquennial programme formally commenced in April 1997.
In collaboration with Prof Stratford’s group a series of regioisomeric derivatives of a 1—methylindole—4,7—dione were studied, substituted with a 2—acetoxybenzoate leaving group linked through the (indol—2—yl)methyl or (indol—3—yl)methyl (or propenyl) positions.
Reductive elimination of the leaving group occurred from the (indol—3—yl)methyl derivatives (Figure 1, pathway I) but not the 2—substituted regioisomers (pathway II), indicating that only the C—3 position may be utilised in bioreductively—activated drug delivery.
www.graylab.ac.uk /lab/report98/pw/pw.html   (3623 words)

  
 SN1 leaving group - Student Doctor Network Forums
A good leaving group is one that can have its conjugate base stabalized by resonance.
If there is no resonance characteristics on the leaving group then a good leaving group is generally a weak base.
As for what makes a good leaving group, it depends on the conjugate base of the acid.
forums.studentdoctor.net /showthread.php?t=139172   (645 words)

  
 Racepoint : News / Events / Awards   (Site not responding. Last check: 2007-10-12)
Racepoint Group, www.racepointgroup.com, is one of the fastest growing public relations agencies in the country, focused on high growth markets including technology, health and sciences.
Digital Influence Group, www.digitalinfluencegroup.com, is the world's first communications company specializing in constituency management within digital channels.
W2 Group is an ecosystem of technology-rich, strategic, creative and results-oriented marketing services companies that provide a unique and distinct set of data-driven, digitally delivered and industry focused marketing services for influencing constituent groups at every level.
www.racepointgroup.com /pr_09272004.asp   (947 words)

  
 Soc 257 Leture: Leaving NRMs
A person leaving a high demand NRM may, on leaving, conclude: "I didn't have the stuff it takes to be a truly committed member.
Since each of these factors may impact how people recall their membership in a group, accounts of leaving need to be treated as data for anlaysis.
As group progresses, it's world transformation goals are usually restructured, sometime abandoned.
religiousmovements.lib.virginia.edu /lectures/leave.html   (799 words)

  
 Metal ion catalysis during group II intron self-splicing: parallels with the spliceosome -- Sontheimer et al. 13 (13): ...
leaving group by a metal ion is not required for the reaction.
Splicing of precursors to mRNAs by the spliceosomes.
Group II intron splicing in vivo by first-step hydrolysis.
www.genesdev.org /cgi/content/full/13/13/1729   (6886 words)

  
 Modified carbon products with leaving groups inks and coatings containing modified carbon products - Patent 5968243
The modified carbon product of claim 20, wherein said spacer group is a group with at least one hydrogen on the carbon which is adjacent to -AG.
The modified carbon product of claim 41, further comprising a second organic group attached to said carbon, wherein said second organic group comprises a) an aromatic group or a C.sub.1 -C.sub.12 alkyl group and b) an ionic or ionizable group wherein the ionic or ionizable group is not eliminated from the organic group.
The spacer group is preferably any ethylene group or a substituted ethylene group with at least one hydrogen on the carbon which is adjacent to -AG.
www.freepatentsonline.com /5968243.html   (6543 words)

  
 Starting a Group
Leaving one person to do everything is always a recipe for disaster.
Inevitably, that one person will be ill or unavailable when you really need him or her, and no one else in the group will have any idea how to get things done.
If you’re running a study group, you may only want to take new members when the group is starting a new project so you won’t have to catch someone up halfway through.
www.suite101.com /article.cfm/wicca_witchcraft/111408/2   (464 words)

  
 University of Oregon Men's Center   (Site not responding. Last check: 2007-10-12)
This is a process group for men focusing on a wide variety of issues, although within the context and perspective of being male and Masculinity.
In order to obtain the most from the group, members will be asked to suggest ways of conducting it.
Group members are expected to observe mutual respect for other group members and their opinions
www.uoregon.edu /~counsel/UOMC/group.htm   (204 words)

  
 When is it time to leave a group?   (Site not responding. Last check: 2007-10-12)
Let's also assume that the group has not become intensely political (leaving any heavily politized group is always most difficult).
Tell them you have enjoyed your experience in the group, and that you just feel it is really time to have new experiences.
If you keep everything on a positive level; make sure the leader(s) don't feel they have done anything wrong; and that you have nothing against the group or the people in it, you will be able to have a clear, positive break with the group.
www.bookmice.net /darkchilde/spirit/leave2.html   (494 words)

  
 Reading Group Guide | LEAVING A TRACE by Alexandra Johnson
Leaving a Trace, Alexandra Johnson's inspiring new book, reinvents journal keeping, showing readers how to leave a lasting piece of work about their lives for themselves or others.
Whether you've kept journals for years or quit after only a few pages, Leaving a Trace will help you start and keep journals successfully—as well as transform your material into longer projects or creative work.
Today many book groups are turning into journal writing groups.
www.readinggroupguides.com /guides/leaving_a_trace.asp   (867 words)

  
 Leaving Groups   (Site not responding. Last check: 2007-10-12)
Substrates for nucleophilic substitution reactions are characterized by the presence of leaving groups.
Leaving groups are substituents which are able to leave as a stable, weakly basic species.
In some cases, leaving groups leave as anions, in other they leave as neutral molecules.
www.cem.msu.edu /~parrill/lg.html   (82 words)

  
 Reactions Involving Alcohols
Water is a much better leaving group since water is a far weaker base than Hydroxide ion.
The mesylate group or the Tosylate group is a far better leaving group, better than even the protonaed Hydroxyl group.Nucleophilic reactions occur much faster and yields of substitution product are much improved.
This improves the leaving group ability of the Hydroxyl as was explained earlier.
members.aol.com /logan20/alc_rx.html   (911 words)

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