Experimental techniques in high-vacuum anionic polymerization

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Once potassium is molten, sodium also melts and dissolves into it.

“Na also begins to melt and is dissolved into the molten potassium.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The authors have had good results with dry powdered or granular lithium containing 0.5% sodium.

“We have had good success in the use of a dry powder or granular form that contains $0.5% Na.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

Adding a coinitiator to DLI breaks up aggregates, improves solubility, and promotes faster initiation.

“An additive is advised to be used as a coinitiator with the use of this reagent to break up the aggregations, promote the solubility, and encourage a faster initiation event.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Less volatile compounds tend to perform better when an all-glass path with minimal vertical rise is used.

“The less volatile compounds tend to behave much better through the employment of an all-glass path having as little a vertical climb as practical.”

May combine two claims.

Lithium dispersion in paraffin tolerates ambient atmosphere for short periods, but removing the paraffin later by hexane washing is experimentally laborious.

“Li dispersion in paraffin is rather tolerant of the ambient atmosphere for short periods; however, it is later experimentally laborious to strip the paraffin away, by the washing with hexanes, and we therefore do not recommend it.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Diphenylhexyllithium is an effective drying agent for ether solvents.

“A more benign chemical substitute is diphenylhexyllithium (the adduct of BuLi and DPE), which works well as a drying agent for ethereal solvents.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The sec-BuOLi reaction is exothermic, so it is added slowly with ice cooling, but the product is stable and can be warmed to room temperature or higher.

“The reaction is exothermic, so the addition is made slowly with the reactor chilled in an ice bath, but the product is stable; hence the reactor may be allowed to warm to room temperature or even higher.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The reaction between sec-BuCl and lithium metal is exothermic and needs control, and the sec-BuLi product is not stable at room temperature for long periods.

“The reaction is exothermic and must be controlled; moreover, the reaction product is not stable at room temperature for long periods.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Calcium hydride can frequently be reused multiple times, particularly with nonhygroscopic solvents and systems kept closed.

“It can often be reused several times, especially in cases in which it is used to treat nonhygroscopic solvents and in systems that are kept closed from the atmosphere.”

May combine two claims.

The liquid-nitrogen trap captures solvent molecules, so Tesla coil noise appears only on the near side.

“Solvent molecules, contrarily, are captured there and produce noise only in the vacuum line on the near side of the trap (C).”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Fine dry lithium powder has worked well in the past but must be carefully protected.

“We have had good success in the past with a fine dry Li powder, which must be carefully protected.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

After being opened several times, organometallic stock reagents often turn cloudy, yet their effectiveness as purification agents is usually retained.

“These reagents often become cloudy after opening several times; however, their potency is generally retained to be effective as purification agents.”

Probably not a substantial claim: may not pass S3 (load-bearing).

After sec-BuLi starts to degrade, as shown by cloudiness or precipitate in the ampoules, the decomposition appears to speed up considerably.

“Once the reagent begins to deteriorate (as evidenced by cloudiness or precipitate in the ampules), the decomposition seems to progress further much more quickly.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Lithium sec-butoxide has generally worked well as a coinitiator in their experience.

“We generally have good success with the use of lithium sec-butoxide (sec-BuOLi).”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

sec-BuLi is stable when sealed in glass under vacuum at low temperature and can often be stored for up to several years at -20°C.

“sec-BuLi is quite stable, sealed in glass under vacuum at cold temperatures.It may often be kept for periods of up to several years at À20 8C.”

Probably not a substantial claim: may not pass S3 (load-bearing).

At room temperature the potassium-sodium alloy stays liquid.

“The alloy remains a liquid at room temperature.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The greased joint at a vacuum port typically holds its seal for 1-3 weeks, varying with the solvent.

“Generally, the greased vacuum joint will last with integrity for 1-3 weeks, depending on the nature of the solvent.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Potassium melts at a lower point than sodium during heating.

“K will melt before Na melts.”

Probably not a substantial claim: may not pass S3 (load-bearing).

They have successfully stored DLI at room temperature for many months.

“We have had success at storing the reagent at room temperature for many months.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

PEB and sec-BuLi are soluble, while the DLI adduct becomes insoluble over time and is stable at room temperature.

“Both PEB and sec-BuLi are soluble; the DLI adduct is insoluble with time and stable at room temperature.”

Probably not a substantial claim: may not pass S3 (load-bearing).

When colored anions are adducted into Si, their color completely dissipates.

“As colored anions are adducted into Si, a visual indication is that their color completely dissipates.”

• cites [34] 34. Uhrig, D.; Mays, J. W. Macromolecules 2002, 35, 7182.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [35] 35. Pennisi, R. W.; Fetters, L. J. Macromolecules 1988, 21, 1094.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

A light precipitation of LiCl may appear in concentrated solution; it does not hinder linking and is evidence of success.

“If the solution is concentrated, a light precipitation of LiCl may be noticed; this is inconsequential to the linking progress and indeed is evidence of the success.”

• cites [34] 34. Uhrig, D.; Mays, J. W. Macromolecules 2002, 35, 7182.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [35] 35. Pennisi, R. W.; Fetters, L. J. Macromolecules 1988, 21, 1094.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

The first equivalent of active polymer chain is generally incorporated into a chlorosilane within several minutes.

“The incorporation of the first equivalent of active polymer chain into a chlorosilane is generally accomplished within several minutes, although we usually wait hours.”

• cites [34] 34. Uhrig, D.; Mays, J. W. Macromolecules 2002, 35, 7182.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [35] 35. Pennisi, R. W.; Fetters, L. J. Macromolecules 1988, 21, 1094.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

A polymerization from DLI can be accomplished using the Canadian apparatus adapted as in Figure 54.

“For example, with an apparatus such as the one shown in Figure 54, a polymerization from DLI is accomplished.26”

• cites [26] 26. Worsfold, D. J.; Bywater, S. Can J Chem 1960, 38, 1891.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Controlled anionic polymerization is a distinctive synthetic route to a broad range of model linear and branched polymers and copolymers.

“Controlled anionic polymerization is a unique synthetic means toward a large range of model linear and branched polymers and copolymers.[4][5][6][7]”

• cites [4] 4. Hadjichristidis, N.; Iatrou, H.; Pispas, S.; Pitsikalis, M. J Polym Sci Part A: Polym Chem 2000, 38, 3211.Not checked yet

  Not checked in the free run.

• cites [5] 5. Morton, M. Anionic Polymerization: Principles and Practice; Academic: New York, 1983. sourceNot checked yet

  Not checked in the free run.

• cites [6] 6. Hsieh, H.; Quirk, R. Anionic Polymerization: Princi- ples and Practice; Marcel Dekker: New York, 1996. sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Sodium quickly develops an oxide layer, so air exposure should be limited to about a minute.

“It quickly builds up a coating of oxide, so it should be protected from exposure to the air for periods longer than 1 min.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Substances that boil below 100 C at ambient pressure can generally be distilled at room temperature on the high-vacuum manifold.

“Generally, liquids that boil below 100 8C under ambient conditions are distilled easily at room temperature with the high-vacuum manifold.”

Classified as probably not a substantial claim.

In anionic polymerization, the macroanion formed after polymerizing a monomer from the reactivity scale can initiate polymerization of any monomer to its right.

“In other words, the anionic polymerization of each monomer in the scale leads to a macroanion reactive enough to initiate a polymerization of any monomer to its right.”

Probably not a substantial claim: may not pass S3 (load-bearing).

A frozen liquid thawing in a reservoir poses danger because the flask can rupture.

“Finally, the thawing of a frozen liquid in a reservoir is quite dangerous because there is a potential for the flask to break.”

May combine two claims.

Low-volatility compounds can still be moved by vacuum distillation; they often need slight heating above room temperature to raise vapor pressure, which causes more global condensation like in conventional distillation.

“Compounds that have a low volatility (usually monomers) can still be transported with distillation techniques under vacuum.It is best to require them to travel only short distances.Often they must be heated at least slightly above room temperature to increase their vapor pressure; this leads to a more global condensation behavior such as is observed in conventional distillations.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

The vacuum line is not designed to contain internal pressures greater than the surrounding atmosphere.

“Keep in mind also that the vacuum line is not designed to withstand internal pressures greater than the surrounding atmosphere.”

May combine two claims.

DLI is a difunctional, hydrocarbon-soluble organolithium initiator made by adding sec-BuLi twice to a difunctional monomer that cannot polymerize on its own.

“DLI, 21 a difunctional hydrocarbon-soluble organolithium initiator, is synthesized through a twofold adduction of sec-BuLi to a difunctional monomer that cannot itself polymerize.”

• cites [21] 21. Gilman, H.; Cartledge, F. K. J Organomet Chem 1964, 2, 447.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

A messy vacuum line at best delays reaching desired vacuum and at worst undermines the reliability of all syntheses run through it.

“The result of a messy vacuum line is at best a waste of time in waiting for desired vacuum levels to be achieved and at worst a compromise to the integrity of all synthetic experiments conducted through its use.”

Classified as probably not a substantial claim.

An alkali mirror offers a very large, highly pure solid alkali surface that is otherwise unavailable.

“The main advantage of a mirror is that it has an extremely large solid alkali surface area of very high purity that cannot be otherwise obtained.”

Probably not a substantial claim: may not pass S3 (load-bearing).

A Tesla coil is a handy instrument for assessing the vacuum level in the line.

“The Tesla coil is a very convenient tool for checking the level of the vacuum in the vacuum line.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

CaH2 evolves gas, so large-scale solvent distillation from it may need intermittent pauses and degassing to maintain a high rate.

“The use of CaH 2 is attended by the evolution of gas so that even if the system has been degassed earlier, it will likely be necessary to temporarily halt the distillation of a large quantity of solvent from CaH 2 and degas the system to maintain a high distillation rate.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Quenching concentrated organometallic solutions can cause violent fire; if not already diluted, they should first be diluted with hexane.

“Concentrated solutions may often not be quenched without the violent attendance of fire; therefore, if the reagent is not already diluted with leftover solvent or monomer, then it should first be diluted with a small quantity of hexane.”

• AssumptionRests on an assumption: Organometallic reagents are pyrophoric.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Because mercury is a heavy metal, its vapor carries substantial momentum, a property useful in a diffusion pump.

“(Mercury is a heavy metal; therefore, a stream of its vapor has a large momentum that is desirable in an application such as this.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Mercury shows low affinity for organic compounds that might pass through the pump.

“Moreover, mercury does not have a high affinity for organic compounds that may be allowed to sweep through the pump.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

The potassium-sodium alloy is among the most serious fire risks in a laboratory.

“Keep in mind that the K/Na alloy is potentially one of the great fire dangers in the laboratory.”

• AssumptionRests on an assumption: The potassium-sodium alloy is an extremely powerful reducing agent.

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Calcium hydride is the drying agent most often employed.

“This is the most commonly used drying agent employed.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Oxygen may condense within a container cooled by liquid nitrogen and then closed, which can lead to an explosion.

“Oxygen can condense inside the container: the result is potentially explosive.”

Probably not a substantial claim: may not pass S4 (based).

Hydrocarbon solvents such as benzene and hexanes do not absorb water appreciably.

“These solvents are not appreciably hygroscopic”

Probably not a substantial claim: may not pass S3 (load-bearing).

In the 1970s, Fetters used a purge apparatus to make polystyrene samples with controlled molecular weights in the millions.

“For example, by using such an apparatus in the 1970s, Fetters 23 was able to produce polystyrene samples with controlled MWs in the range of millions.”

• cites [23] 23. Ignatz-Hoover, F. Ph.D. Thesis, University of Akron, 1989.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Chilling the receiving flask reduces pressure at that point, causing solvent to travel from source to destination without condensing in the manifold.

“By the chilling of the destination to which the solvent must be collected, the pressure is reduced there, and the sol-vent travels from the source to the destination without condensation ever occurring in the manifold.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Although leftover CaH2 is quenched with water before disposal, direct addition of water is too violent.

“The leftover CaH 2 is deactivated with water before its disposal, but the reaction is too violent to simply add water to the chemical.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Gas molecules entering the diffusion pump are carried toward the mechanical pump and cannot flow back.

“Thus, gases are swept toward the mechanical pump and prohibited from returning.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Mercury in the mechanical pump implies mercury contamination in the laboratory room.

“Also realize that if there is mercury in the mechanical pump, then there is mercury in the room.”

Classified as probably not a substantial claim.

Refreezing the liquid shifts equilibrium, allowing dissolved gases to leave and be pumped away.

“Each time the liquid is refrozen, the equilibrium is shifted so that dissolved gases may escape and be removed by the vacuum pump.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Sodium is the alkali most frequently used for purification in anionic polymerization.

“This reagent is the most commonly used alkali in anionic polymerization purification procedures.”

Probably not a substantial claim: may not pass S3 (load-bearing).

For quenching sodium, isopropyl alcohol is safer than methanol.

“Isopropyl alcohol is a safer choice.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

SEC eluograms before and after end-capping should coincide and show no dimerization of macroanions.

“SEC eluograms, before and after the end-capping procedure, should coincide and lack evidence of dimerization of the macroanions.”

May combine two claims.

A portable manifold permits less glassblowing while still preventing high-boiling compounds from entering the permanent vacuum manifold.

“It is possible to do less glassblowing and still keep highboiling compounds out of the permanent vacuum manifold through the use of a portable manifold, which may be easily cleaned and reused many times.”

May combine two claims.

On the vacuum line, bubbles appear abruptly throughout the reservoir, making solvent bumping and splashing into the line likely.

“The result is that bubbles form suddenly and anywhere in the reservoir; solvent is easily bumped and splashed into the vacuum line.”

Probably not a substantial claim: may not pass S3 (load-bearing).

If water is added slowly or only at the bottom, the reservoir flask is more likely to break.

“If water is added too slowly or added only to the bottom of the reservoir, it is much more likely that a rupture of the flask will occur.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

A portable short manifold is a viable choice for compounds that boil below 200°C at ambient conditions.

“This short cut is a quite viable option for compounds that boil below $200 8C under ambient conditions.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

These CaH2 quenching procedures are vigorous, produce flammable hydrogen, and belong in a fume hood.

“Either of these deactivation methods is still quite vigorous, is accompanied by the evolution of flammable hydrogen gas, and should be accomplished in the hood.”

May combine two claims.

Turbo molecular pumps are highly delicate and can be harmed by careless operation, for example accidental gas entry, with high repair cost.

“Nevertheless, such pumping units are exceedingly delicate and do not suffer careless use (e.g., accidental in-streaming of gas) without great expense.”

• AssumptionRests on an assumption: Chlorosilanes can severely damage turbo molecular pumps.

Probably not a substantial claim: may not pass S3 (load-bearing).

A diffusion pump can capture gas particles and move them in the direction of a mechanical pump.

“the diffusion pump can entrain gaseous particles and direct them toward a mechanical pump.”

Probably not a substantial claim: may not pass S4 (based).

The quality of organolithium reagents is very important for successful and reproducible polymerizations.

“The quality of organolithium reagents is very crucial to successful reproducible polymerizations.”

Classified as probably not a substantial claim.

A pair of pumps operating in series permits attainment of a very high vacuum.

“Two pumps working in series, such as depicted in Figure 1, allow the attainment of a very high vacuum.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Solvent bumping into the vacuum line is usually hard to prevent if a reservoir is filled beyond half capacity.

“It is usually very difficult to avoid bumping solvents into the vacuum line if the reservoirs are more than half full”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Placing a water dish outside the cylinder can cool the solvent a little below manifold temperature, reducing solvent movement into the grease.

“through the simple evaporative action of the water, the solvent inside the reservoir can be kept a degree or so cooler than the vacuum manifold (and the greased union), with the effect of retarding solvent migrating into the grease and compromising the seal.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

A system can be judged well degassed if, on first opening to the pump, the Tesla coil is silent at point B.

“A system may be judged to be well degassed if, at the first moment of opening the equilibrated system to the vacuum pump, there is no noise from the Tesla coil at point B.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Sodium mirrors are most frequently used, but potassium mirrors are equally easy to prepare.

“Na mirrors are the most common (although K mirrors can be just as easily prepared).”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

THF is useful for cleaning most organic residues.

“Solvents such as tetrahydrofuran (THF) are also useful for most organic compounds.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Powdered lithium in excess is highly reactive.

“Excess lithium is extremely reactive when it is in a powder form.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Methanol reacts dangerously with sodium unless the metal is already under an organic liquid that dilutes the methanol.

“The reaction with methanol is dangerous unless the metal is already under another organic medium that will dilute the methanol.”

May combine two claims.

The second equivalent of PSLi can be titrated cleanly, and PILi can be titrated as a third equivalent.

“Because it is much more difficult to add a third arm of polystyrene to Si than it is to add a second one, it is possible to titrate the second equivalent of PSLi cleanly.Similarly, PILi may be titrated as a third equivalent.”

• AssumptionRests on an assumption: Adding a third polystyrene arm to Si is much more difficult than adding a second one.

Probably not a substantial claim: may not pass S3 (load-bearing).

Purging is also required for lower molecular weight products when the designed molecular weight must be precise.

“It is also necessary to employ this technique in the provision of lower MW materials if precision is required in the designed MW of the product.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Dropwise methanol addition to organometallic compounds produces heat and hydrocarbon gas.

“The dropwise addition of methanol is accompanied by the evolution of both heat and gaseous hydrocarbon (e.g., butane).”

Probably not a substantial claim: may not pass S3 (load-bearing).

Potassium demands greater caution than sodium.

“This alkali metal is also somewhat regularly used and requires even more care than sodium.”

• AssumptionRests on an assumption: Potassium spontaneously ignites in air.
• AssumptionRests on an assumption: Potassium reacts explosively with water and alcohol.

May combine two claims.

In hydrocarbon solvents, anionic polymerization proceeds very slowly, so the sequence in which reagents are added to the solvent is not necessarily critical.

“The kinetics of polymerization in hydrocarbon media are very slow, and this means that the order of incorporation of reagents into the solvent is not necessarily crucial.”

• cites [1] 1. AND sourceNot checked yet

  Not checked in the free run.

• cites [2] 2. Fetters, L. J. J Res Natl Bur Stand Part A: Phys Chem 1966, 70, 421.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Once ambient gases are removed, the atmosphere over a liquid in a closed high-vacuum system consists only of its vapor pressure.

“With ambient gases out of the way, the remaining atmosphere over a liquid in a closed high-vacuum system is simply the vapor pressure of the liquid itself.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Hydrofluoric acid is one of the most effective cleaners for complex glassware.

“It is, however, one of the most effective methods of cleaning intricate glassware.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Dilute aqueous alkali can dissolve small quantities of silicone grease effectively.

“Aqueous alkali solutions tend to work well at dissolving small quantities of silicone grease.”

Probably not a substantial claim: may not pass S3 (load-bearing).

A turbo molecular pump can achieve the same vacuum level as a diffusion pump.

“A turbo molecular pump is able to deliver the same vacuum capability.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

For withdrawing organometallic solutions, the second needle-transfer approach is superior.

“The second method is the better technique.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The final linking is monitored by SEC; when no further shift toward higher molecular weight is seen, linking is judged complete.

“The final linking is monitored by the removal of small aliquots and their analysis with SEC.When no fur- ther shift toward a higher MW is discerned according to the SEC profile, the linking is judged to be complete.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

During polymerization, the external alcohol bath should be set beneath the level of the solvent inside the reactor; otherwise monomers can accumulate and polymerize on the glass above the solution, producing an inhomogeneous system.

“During the polymerization, the external alcohol bath should be set to bathe the apparatus at a level beneath the level of the solvent inside the reactor.Otherwise, as monomers are incorporated, it is easy for them to accumulate and polymerize on the glass above the level of the solution, and an inhomogeneous system results.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Distillation is the cleanest method of monomer transport for adding all monomers after the first one because the reactor is not purged.

“Distillation is recommended for the addition of all monomers after the first one because the reactor is not purged: distillation is the cleanest method of monomer transport.”

Probably not a substantial claim: may not pass S3 (load-bearing).

It is difficult to take preliminary aliquots of the polymerization between additions of successive monomers.

“It is consequently difficult to take preliminary aliquots of the polymerization between additions of successive monomers.”

• AssumptionRests on an assumption: sec-BuLi reacts with THF somewhat more rapidly than n-BuLi, even at -78 C.
• AssumptionRests on an assumption: Active polymer chains may be terminated if the reactor is allowed to warm during polymerization.

May combine two claims.

Freezing the linking reactor with dry ice or liquid nitrogen during in-distillations is extremely dangerous because it can cause inhomogeneous freezing, stress on the flask, and glass cracking.

“During the in-distillations, it is extremely dangerous to freeze the linking reactor with either dry ice or liquid nitrogen.Often the thick polymer syrup is strongly adhered to the glass, or the system freezes in an inhomogeneous manner.(Two different layers of the substance freeze: one is the concentrated polymer solution, and the other is the incoming solvent.)The result is that a lot of stress”