Chemistry (enantiomers etc.)

[Uwe Hirayama]

Dear colleagues,

I repost this message, because I did not receive a copy.
Sorry if this causes any unease.

Well, here it goes:

I am translating a report with the Japanese title:
分別結晶法による光学分別における合理的な分割操作条件の設定
which comprises some critical expressions and
I feel I need some assistance.

1. The title of the article (from 1968)

What do you think of a translation as:

"(Selection of) rational (optimal?) conditions and
separation procedures in separation of optical isomers
by fractional crystallization"?

2. 溶解量
Is there a more handy expression than "dissolved amount"?

3. 2量体, 活性体, 両活性体

2量体 is different from 二量体 (dimer) and I consider it
to be an abbreviation for 二種の量体 or sth alike. In ,e.g.,
ラセミ体が溶解状態で2量体として挙動することはない。
it IMHO relates to the two optical isomers (enantiomers,
antipodes) comprised in the racemic mixture or racemate.
I assume that 量体 or simply 体 are Japanese renderings of
"mer" (as in iso*mer*, di*mer*, poly*mer* etc.) which
comes from Greek meros (or meris) with the meaning "part".

活性体 seems to express also one optical isomer of a
compound having two (or more?) varieties with different
optical properties, and 両活性体 seems to indicate the
two varieties in e.g. racemic mixture (e.g. L-体 and D-体).

With that background (I hope it is clear enough) how would you
call
2量体
活性体
両活性体
L-体
D-体
(Here are some candidates, but I do not know whether they are
or which of them would be appropriate: isomer, optical isomer,
enantiomer, (optical) antipode, or xyz)

I hope this is all what will come up for this article,
but who will know ...

TIA for your nice assistance,

Uwe Hirayama
JP2GER TRSL
hira...@t-online.de

[Mark Spahn]

Uwe Hirayama asks, How would you call

2量体
活性体
両活性体
L-体
D-体

You probably know already that the L- and D-
stand for the prefixes lev(o)- and dextr(o)-,
but a Google search produces few hits for "dextromer"
and no hits for "levomer".
Hope this helps more than it obscures.
-- Mark Spahn (West Seneca, NY)

[Matthew Schlecht]

> 分別結晶法による光学分別における合理的な分割操作条件の設定

     I would write:
"Establishment of reasonable resolution conditions for optical separation by fractional crystallization."

> 2. 溶解量
> Is there a more handy expression than "dissolved amount"?

     Amount dissolved, [quantity/portion] dissolved, dissolved [quantity/portion]

> 3. 2量体, 活性体, 両活性体
>
> 2量体 is different from 二量体 (dimer)

     That's pretty strange.

> how would you call
> 2量体

two forms, two isomers

> 活性体

active form, active isomer

> 両活性体

both active isomers, both active forms

> L-体

L-form, L-isomer

> D-体

D-form, D-isomer

Matthew Schlecht

[Alan Siegrist]

Uwe Hirayama writes:

> 3. 2量体, 活性体, 両活性体
>
> 2量体 is different from 二量体 (dimer)

In my experience, I have often seen Arabic numerals (e.g. "2") used instead
of their kanji equivalents (here, 二) with exactly the same meaning. So I
would assume that "2量体" means "dimer" no more and no less.

Regards,

Alan Siegrist
Carmel, CA, USA

[Uwe Hirayama]

Thy to Mark, Mike, and Alan for the helpfuil input.

Dear Alan,

you wrote:

>>
>> 2量体 is different from 二量体 (dimer)
>
> In my experience, I have often seen Arabic numerals (e.g. "2") used instead
> of their kanji equivalents (here, 二) with exactly the same meaning.

So do I.

> So I
> would assume that "2量体" means "dimer" no more and no less.

However, the article is on separation of optical isomers, particularly
L- and D-glutamic acid in free form and salt form. ASFAIK in racemic
mixtures you have both the L-form and the D-form and with the knowledge
as background that racemate solutions do not "rotate" the plane of the
polarized light (i.e. they show an optical inactive behavior) because
the contributions of the enantiomeric form compensate each other,
I assume that speaking of dimers in this context makes less sense
than peraphrasing 2量体 with 2種類の量体 (with 量体 as "-mer).

2量体 comes up in "ラセミ体が溶解状態で2量体として挙動することはない。"
and in the following sentence:

分子量、あるいは氷点降下等分子量の関与する物性値の
測定結果からは2量体が存在しないことが明らかでもなお、
溶液内に相互作用はあると著者は考えている。

(rough tentative translation)

Even it is clear that 2量体 do not exist the authors
suppose (from measuring results on molecular weight and
physical properties (values?) related to molecular
weight as, e.g., freezing-poiunt depression, that there
is some interaction in the solutions.

Would you translate "dimer" in this context?

Kind regards,

Uwe Hirayama

[TimL...@aol.com]

Hi Uwe,

 

Yes, I think I would say dimers here, but I would say "are not present", rather than "do not exist". They seem to be discussing a situation where molecules pair up transiently in the solution, the bonding being quite weak, not like the covalent bonding which may be found seen in stable, readily isolated dimers.

 

HTH a bit,

Tim

[TimL...@aol.com]

found seen = found. Sorry, the heat is getting to me

 

Tim

 

 

[Alan Siegrist]

Uwe Hirayama writes:

> >> 2量体 is different from 二量体 (dimer)
> >
> > In my experience, I have often seen Arabic numerals (e.g. "2") used
> > instead of their kanji equivalents (here, 二) with exactly the same
> > meaning.
>
> So do I.
>
> > So I would assume that "2量体" means "dimer" no more and no less.

<snip>

> Would you translate "dimer" in this context?

Yes, I would. I agree completely with Tim on this.

The author is stating that a dimer is not formed and is not present; this is
completely consistent with this solution being a racemic mixture of
enantiomers.