People often say tznius when they mean to say tzanua. Do you know of any other examples in Hebrew, Aramaic, or Yiddish in which people use the noun but they really mean to use the adjective?
Monday, 27 July 2015
halacha theory - Can one use terumah to light a stove?
In Pesachim 23a, the gemara (in the name of Rav Papa) derives from Numbers 18:27 that the prohibition of terumah to non-priests only applies to eating and drinking, but not to other forms of enjoyment. The example given in the gemara pertains to the mishna in Eruvin 3:1, to the effect that a yisrael can use terumah for his eruv.
According to this article at Virtual Beit Midrash, this statement in the gemara has been understood to mean that terumah is only forbidden for consumption by yisraelim, but not for regular enjoyment (מותרת בהנאה לזרים). As the author of the article (ר' מתן גלידאי) makes clear, this ruling created problems for the rishonim, concerning how to align it with the mishna in Terumot 11:9. There, the mishna makes clear that kohanim may feed their animals terumah, but that yisraelim cannot. If there is no prohibition of deriving enjoyment from terumah, why would a yisrael be prevented from feeding it to his livestock?
The resolution acc. to that same article, which was proposed by Rabbeinu Tam, is to the effect that the Torah permits yisraelim to enjoy terumah, but forbids them from any form of enjoyment that results in the eradication of that terumah (הנאה של כילוי). This explains why a yisrael would be forbidden from feeding his livestock with terumah, as well as why the mishna in Terumot 11:10 would permit his burning terumah for the public good - as long as it was with the permission of a kohen.
But how does it align with the mishna in Terumot 10:4? There, the mishna speaks of somebody lighting his stove with cumin of terumah (תנור שהסיקו בכמון של תרומה). The discussion as to whether or not bread cooked upon this stove is permissible for consumption is one that pertains to the separate issue of whether or not aroma is a tangible substance (ריחא מילתא היא), but so far as the actual burning of the cumin is concerned, the following is what the Bartenura has to say:
ואי משום דהוסק התנור בתרומה, אין איסורה איסור הנאה
And concerning the fact that
he lit the stovethe stove was lit with terumah, its prohibition is not a prohibition of enjoyment [but only of consumption].
How does this align with the prohibition of הנאה של כילוי, as expressed by Rabbeinu Tam?
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To compound this problem, both opinions are brought (contradictorily) in Kehati's peirush on the Mishna. In his commentary on Terumot 10:4, he quotes the Bartenura as follows:
ומה שהוסק התנור בתרומה אין בזה איסור, שאין התרומה אסורה לזרים בהנאה אלא באכילה בלבד
And concerning the fact that
he lit the stovethe stove was lit with terumah, this is not prohibited, since terumah is not prohibited to non-priests when it comes to enjoyment but only when it comes to eating [and drinking].
Later, however, in his introduction to Terumot 11:10, he explicitly declares the following:
ואף על פי שתרומה אינה מאיסורי הנאה, ומותרת היא בהנאה לזרים, מכל מקום הנאה של כילוי, כגון בענייננו שההנאה באה משריפת התרומה, אסור היא לזרים
Even though terumah is not of those things that are forbidden from enjoyment, and is permitted for the enjoyment of non-priests, the enjoyment that comes from eradication (הנאה של כילוי) - such as is found in this instance, in which the enjoyment comes from the burning of terumah - is forbidden to non-priests.
--
In summary, the two ways of putting this question are as follows:
If yisraelim are allowed to enjoy terumah so long as they do not destroy it, why does the Bartenura suggest that burning it (in Terumot 10:4) is okay?
How can Kehati explicitly say that burning terumah (in Terumot 10:4) is okay, but then say no less explicitly (in Terumot 11:10) that burning terumah is impermissible?
organic chemistry - Birch Reduction Of Anthracene
Which ring of anthracene is reduced during Birch Reduction? What will the final product look like? Why?
My teacher said that the more electron deficient ring should undergo the reduction but I couldn't figure it out still. Any ideas?
Answer
There are two ways of rationalising this. One way is to look up or qualitatively determine the frontier orbitals (HOMO and LUMO) of anthracene, the other is to think about the stability of various radical anions.
But first, a quick note on the Birch reduction and its mechanism. As you may know, the $\ce{Na/NH3}$ system effectively works as a single electron transfer reagent. The electron is added to the π system’s LUMO, and the resulting radical anion is trapped by a proton (donated from a proton source; e.g. added ethanol) to give a radical. This radical is still electron-deficient and thus susceptible to another single electron transfer reduction resulting in a second anion which again is captured by a proton resulting in the reaction product.
A great resource for frontier orbitals is the WOrbit page of Hans-Ulrich Wagner from the LMU Munich. Among the systems whose orbitals you can look at is, luckily, anthracene. For posteriority, I have included the HOMO and LUMO pictures in the image below.
Figure 1: LUMO and HOMO of anthracene as calculated on the WOrbit page linked above.
The LUMO is of importance; after all, we are adding an electron. We see that the MO is most localised on carbons 9 and 10 of the central ring — thus, this is where the first electron will be added in a localised picture, and this is where the first proton will capture.
Scheme 1: First reduction sequence.
As I drew in scheme 1, this gives us the radical 3, of which I have only shown one resonance structure. Applying the same analysis for the second step will tell us that the second electron will be added exactly at that position where I have drawn the radical (data not shown). Thus, we find that the central ring is reduced as depicted in scheme 2.
Scheme 2: Second single electron transfer and subsequent reduction of radical 3 to 9,10-dihydroanthracene 5.
If we consider the $+I$ effect on substituted carbons, we see that we only need to consider the three structures shown in scheme 3 below; reversing charge and radical in structure 2 would result in the negative charge being on the tertiary carbon which is much less favourable when compared to the secondary one.
Scheme 3: Possible radical anions of anthracene.
At first, it looks like 6 and 7 might be better stabilised structures: 6 effectively represents a methylnaphthalene radical and 7 a naphthylallyl radical. However, if we take a closer look at 2 we see that it can be rearranged in a manner shown in scheme 1 above. If you consider the above drawn structure 3 as a radical anion (i.e. before protonation), notice that the radical is now a diphenylmethyl radical. This diphenylmethyl radical wins in favourability against both naphthyl derivatives.
As a general rule, if you can preserve the aromaticity of a benzene ring the structure is ‘better’ than one where you can’t. And two benzene rings as are present in structures 3 and 4 (and 5) are better than the naphthyl rings of structures 6 and 7. Thus, it is most favourable to reduce the central ring.
Note, by the way, that depending on the conditions employed, 5 is not inert towards further Birch reduction. Mehda, Sen and Ramesh report a triple Birch reduction of anthracene leading to the very interesting tricyclic triene 8 in $80~\%$ yield (scheme 4).[1]
Scheme 4: Synthesis of 1,4,5,8,9,10-hexahydroanthracene.[1]
Reference:
[1]: G. Mehta, S. Sen, S. S. Ramesh, Eur. J. Org. Chem. 2007, 423. DOI: 10.1002/ejoc.200600610.
minhag - 2 Sifrei Torah for close readings
This morning we read Parashat Mishpatim (Exodus 21:1 - 24:18) and the special reading of Parashat Shekalim (Exodus 30:11-16). The custom everywhere I have ever seen is to remove two Sifrei Torah from the ark for the two readings and to wrap up the first before reading from the second. This custom is very appropriate for other special second readings which are often far apart, as this saves time for the congregation instead of waiting while the scroll is rolled.
However, the readings this morning were only about 8 columns apart from each other! In my mind it is certain that rolling the scroll forward eight columns takes much less time than wrapping up the first Torah and opening the second. This is in fact our practice for the reading on a fast day, which skips from Exodus 32:14 to 34:1, a gap of approximately 2 columns, yet we only use one scroll.
Does anyone suggest using just one scroll when the second reading is this close?
I note that the same question applies to Rosh Chodesh on Parashat Chukat when the gap is from Numbers 22:1 to 28:9, also a gap of about 8 columns.
Answer
You are right. There is a Shita of the Meiri Bais HaBechira in Megila that says that on Parshas Shekalim you should only take out one Sefer Torah.
I imagine that the reason the Shulchan Aruch mentions that we use two Sefer Torahs is because of Lo Pelug.
grammar - Feeling unsure about the connection of the two sides of the comma
地図は普通、北を上にして掛かれる。 (From line 7: https://www.docdroid.net/847v2dg/img-20170413-0001-new.pdf.html)
=> "The map is normal, it can hang with the north attached to the top."
I feel very unsure about this one since there is no copula and no connector (like for example 地図は普通で), but I can't make sense of it otherwise. I'm also not sure whether the potential form expresses an ability here or makes an objective statement (I think there was something about that with potential form, please correct me if I'm wrong, I also don't feel like I understood it).
Answer
Is there a typo here? Shouldn't 掛かる be 掛けられる ? If so, it's a passive, not a potential. Try analysing the sentence without 普通 .
地図は、 北を上にして掛けられる means "Maps are hung with North at the top".
Then restore the 普通:
地図は普通、 北を上にして掛けられる means "Maps are usually hung with North at the top".
One problem is that we tend to assume that the 、 punctuation mark is like an English comma, marking off a grammatically distinct section of a sentence. So when we come to one we stop to look at the meaning of what precedes it. That's not what it does: it's best to think of it as simply indicating a point in the sentence where if you were reading it aloud you might pause to breathe. I think what's happened here is that you've come to a comma so stopped to make an interim translation of the first part of the sentence as "the map is usual or ordinary" and then gone on to deal with rest of the sentence, not realising that 普通 is in fact an adverb meaning "usually", "ordinarily" and that this is a general statement about the way maps are hung.
fft - How to apply Hamming Window?
I am new in matlab and signal processing. The time series that have been used are obtained from accelerometer in a building. As far as I understand both the time series' length and window function length(hamming or hanning) should be same. But for smoothing the fourier amplitude spectrum, optimum window length can vary. How this procedure should be apply in matlab?
How can apply a window function that is shorter than my time series.
Thanks for reading!
shabbat songs - Why did the Vilna Gaon not approve of singing the zemiroh “Tzur Mishelo” on Shabbos?
I understand that the Vilna Gaon did not approve of singing the zemiroh “Tzur Mishelo” on Shabbos because it could be valid as Grace after Meals.
But on Shabbos, Grace after Meals is not valid without including “Retzai”; there is no mention of "Retzai" there, so why did he not approve?
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